solar panel installation on sailboat

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Adding Solar Power to a Sailboat

• By Emily Fagan
• Updated: October 18, 2019

During our nearly four-year cruise of Mexico, my husband, Mark, and I lived almost exclusively on 555 watts of solar power charging a 640-amp-hour house battery bank. We anchored out virtually every night aboard our 2008 Hunter 44DS, Groovy , and relied on the sun for power. During one 10-week stretch, while we waited for a replacement engine alternator to arrive, our boat’s solar panels were our sole source of power. We had no backup charging system to turn to, and yet we lived and sailed comfortably the entire time. Mounting solar panels on a sailboat was not difficult, but a few key decisions made a huge difference in how effective our panels were.

A solar-power installation on a sailboat is made up of two independent systems: one system to charge the batteries, and another system to provide 120-volt AC power for household appliances. In the charging system, the solar panels convert sunlight into electrical current and deliver it to the batteries via a solar charge controller. Similar to a voltage regulator, the charge controller acts as a gatekeeper to protect the batteries from receiving more current than they need as they are being charged. In the AC power system, an inverter or inverter/charger converts the 12-volt DC power in the battery into 120 volts AC whenever it is turned on.

Panel Positioning and Wiring Considerations

One of the biggest challenges for sailors installing solar power on a sailboat is finding a place on the boat where the panels will be shaded as little as possible. Just a few square inches of shade on one panel can render that panel all but inoperable. Unfortunately, between the mast, radome, spreaders and boom, shadows cross the deck all day long, especially as the boat swings back and forth at anchor.

What’s worse, if the panels are wired in series rather than in parallel, this little bit of shade can shut down the entire solar-panel array. When we installed solar power on Groovy , we had already lived exclusively on solar power in an RV for over two years. Our RV solar panels had been wired in series, and we had witnessed the array shutting down current production when just half of one panel was shaded.

Choosing whether to wire the panels in series or parallel on a boat affects the wire gauge required, which is why many solar-power installers lean toward wiring the panels in series. Panels wired in series can be wired all the way to the solar charge controller with a thinner-gauge wire than those wired in parallel. This is because the voltage of panels wired in series is additive, while the current remains constant, so the current flowing is just that of a single panel. In contrast, the current flowing from panels that are wired in parallel is additive, while the voltage across them is not. This means that in a parallel installation, the current going to the charge controller is several times higher and requires much thicker cable to avoid any voltage loss over the length of the wire.

Not only is thinner-gauge wire less expensive, but it is also more supple and easier to work with, making the job of snaking it in and around various crevices in the boat and connecting it to the solar charge controller much less of a struggle. Thus the choice between series and parallel wiring boils down to a trade-off between system performance, expense and ease of solar system installation.

Luckily, the size of the wire can be reduced if higher-­voltage solar panels are chosen. Since watts are determined by multiplying volts by amps, a higher-voltage panel that generates the same watts as a lower-voltage panel will produce less current. Therefore, selecting nominal 24-volt panels instead of 12-volt panels allows for the use of thinner wire sizes no matter how they are wired.

Our Marine Solar Panel Design Choices

In our installation, we decided to mount three 185-watt, 24-volt (nominal) Kyocera solar panels high above the cockpit, well aft of the boom, as far away as possible from potential shade. Our Hunter came with a big, solid stainless-steel arch, and we turned to Alejandro Ulloa, a brilliant metal fabricator at Baja Naval Boatyard in Ensenada, Mexico, to build a polished stainless-steel solar-panel arch extension onto the existing structure. He designed the arch extension with integrated telescoping davits to hoist our dinghy as well as support the solar panels. These davits were strong enough — and the lines and blocks had enough purchase — that either of us could lift our light Porta-Bote dinghy with its 6-horsepower outboard without a winch.

We spaced the panels about a half-inch apart and wired them in parallel. Using two twin-lead wires, we snaked the three positive leads and one common ground down through the inside of the arch tubes so they wouldn’t be visible, and placed wire loom over the exposed wires under the panels.

The junction points for the three parallel panels were on positive and negative bus bars inside a combiner box, all mounted in a cockpit lazarette. Inside the combiner box, we installed three breakers, one for each panel. This gave us the ability to shut off any or all of the panels if we needed to (we never did).

We mounted a Xantrex solar charge controller (model XW MPPT 60-150) in a hanging locker, as close to the batteries as possible, in a spot where it was easy to monitor and program. We ran twin-lead wire from the combiner box to the charge controller and from there to the batteries.

Our boat came with three new 12-volt Mastervolt 4D AGM house batteries, all wired in parallel, for a total of 480 amp-hours of capacity. We wanted a bigger house battery bank, and because it is best for the age, type and size of the batteries to be matched, we added a fourth new Mastervolt 4D AGM house battery, which brought our total to 640 amp-hours. Our batteries were installed at the lowest point in the hull, below the floorboards, and they ran the length of the saloon, from just forward of the companionway stairs to just aft of the V-berth stateroom door.

The best way to charge a bank of batteries that are wired in parallel is to span the entire battery bank with the leads coming from the charge controller. We did this by connecting the positive lead from the charge controller to the positive terminal of the first battery in the bank, and the negative lead from the charge controller to the negative terminal of the last battery. By spanning the entire bank, the batteries were charged equally rather than having the charging current focused on just the first battery in the bank.

We feel that AGM batteries are superior to wet cell (flooded) batteries because they can be installed in any orientation, don’t require maintenance, can’t spill (even in a capsize), and charge more quickly. Our Mastervolt batteries, like almost all AGM batteries on the market, are dual-purpose, combining the very different characteristics of both deep-cycle and start batteries. Our batteries work well, but if we were doing an installation from scratch today, we would consider the new Trojan Reliant AGM batteries. These batteries are engineered strictly for deep-cycle use and have been optimized to provide consistent current and maximize battery life.

Our boat came with a Xantrex Freedom 2,500-watt inverter/charger wired into the boat’s AC wiring system with a transfer switch. The inverter/charger performed two functions. While the boat was disconnected from shore power, it converted the batteries’ 12-volt DC power into 120-volt AC power, allowing us to operate 120-volt appliances, like our microwave. When the boat was connected to shore power, it charged the batteries.

Because this inverter/charger was a modified-sine-wave inverter, mimicking AC ­current with a stair-stepped square wave, we also had a 600-watt pure-sine-wave inverter to power our potentially more sensitive electronic devices. We chose Exeltech because its inverters produce an electrical signal that is clean enough to power medical equipment, and they are NASA’s choice for both the Russian and American sides of the International Space Station. For simplicity, rather than wiring the inverter into the cabin’s AC wiring, we plugged ordinary household power strips into the AC outlets on the inverter and plugged our appliances into the power strips. Like the charge controller, the inverter must be located as close to the batteries as possible. Ours was under a settee.

Shade’s Impact on Sailboat Solar Panels

Once our solar installation was completed on our sailboat, we closely observed the effects of shade on our solar-panel array. We were often anchored in an orientation that put the panels in full sun. Just as often, however, we were angled in such a way that shade from the mast and boom covered portions of our panels. It was fascinating to monitor the solar charge controller’s LCD display whenever the sun was forward of the beam — the current from the panels to the batteries fluctuated up and down as we swung at anchor.

Taking notes one morning, we noticed that the charging current was repeatedly creeping up and down between 9.5 and 24.5 amps as the boat moved to and fro. When the entire solar-panel array was in full sun, it generated 24.5 amps of current. When we moved so the mast shaded a portion of one panel, the array generated 15 amps. When it shaded portions of two panels and only one was in full sun, the array produced just 9.5 amps. Of course, it would have been preferable to see a steady 24.5 amps all morning, but this sure beat watching the current drop to zero whenever a shadow crossed a panel.

We discovered that shade makes a huge impact while sailing, too. Surprisingly, it is far worse to have the panels shaded by the sails than to have the panels in full sun but tilted away from its direct rays. One afternoon, we noticed that while we were on a tack that tilted the panels away from the sun, they generated 24.5 amps of current, whereas on a tack where the panels were tilted toward the sun but two of the three were partially shaded by the sails, the current dropped to a mere 10 amps.

Reflections On Our Solar Panel Installation

A wonderful and surprising side benefit of our large solar panels and arch system was that the setup created fabulous shade over the jumpseats at the stern end of the cockpit. Our metal fabricator, Alejandro, placed a support strut at hand-holding height, and sitting in those seats feels secure and comfortable while sailing, no matter the conditions.

After living on solar power for eight years of cruising and land-yacht travel, we’ve learned that you can never have too much solar power. Groovy’s 555 watts was enough to run all our household appliances as needed, including our nearly 4-cubic-foot DC refrigerator, two laptops, a TV/DVD player, and lights at night. However, it was not quite enough power to run all that plus our stand-alone 2.5-cubic-foot DC freezer during the short days and low sun angles of the winter months without supplemental charging from the engine alternator every few days. For the 10 weeks that we did not have a functioning alternator, our solution was to turn off the freezer, which enabled our batteries to reach full charge every afternoon.

Solar power made a world of difference in our cruise. Not only did it allow us to live comfortably and with ample electricity for weeks on end when our engine alternator went on the blink, but as a “set-it-and-forget-it” system, it also gave us the freedom to anchor out for as long as we wished without worrying about the batteries. In our eyes, the solar-panel arch enhanced the beauty and lines of our boat, giving her a sleek and clean appearance. It was true icing on the cake to discover that the panels and arch system also provided much-needed shade over the cockpit and helm from the hot tropical sunshine. If you are preparing for a cruise, consider turning to the sun for electricity and outfitting your sailboat with solar power.

The Installation:

Emily and Mark Fagan offer cruising tips and share their stories and photos on their website, roadslesstraveled.us . They are currently enjoying a land cruise across America aboard an RV.

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What You Need To Know About Boat Solar Panels

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Sunshine and boats are a natural together, so why not use all that free energy? Here’s the lowdown on solar panel selection and installation

I first embraced the idea of solar power while up a pole (literally) in the Atlantic Intracoastal Waterway replacing dead batteries. It was the early 1980s, and I was maintaining buoys, beacons, and other such Aids To Navigation (ATON) for the U.S. Coast Guard, replacing massive, nonrechargeable batteries with rechargeable solar-powered ones. The higher-ups said the solar rechargeables would last six years – twice as long as the one-shot batteries. As the deck-ape in charge of lugging all those batteries up and down the ladders, my back and I immediately appreciated the whole “free power from the sun” thing, a concept I continue to embrace.

The strategy behind s olar energy onboard is simple: A solar panel converts sunlight into electricity, after which wiring conducts it to your batteries for storage until needed. Solar panels are used to keep batteries or banks charged rather than to power equipment directly. This arrangement allows the panels to store generated power whenever produced, while providing a steady source of power to a piece of equipment even when the panel is producing no power.

While they do require an initial outlay, solar panels can easily pay for themselves in money saved and independence gained over their service life. They’re noiseless, have no moving parts, and they provide free electricity for years with minimal maintenance. Solar panels also have the benefit of being modular, letting you start small and add more as your power requirements increase.

The benefits of solar

Almost any boat can benefit from solar power. Whether at a slip, mooring, or on a trailer, boats can keep their batteries topped off without the need for external power. You can also use solar power to supplement or even replace other onboard charging sources, reducing or eliminating the need to run engines or generators to keep batteries topped off (a wasteful practice that burns fuel while wearing down the costliest pieces of equipment onboard).

While underway, it’s a plus to be able to recharge a dead battery in an emergency – say, to operate a VHF radio or navigation gear. While dockside, solar panels keep batteries charged and vital systems (such as bilge pumps) up and running without the need for shore power.

Just about any boat can benefit from solar power, whether it’s to keep batteries topped off or supplement other onboard charging sources.

Mount solar panels where they are exposed to maximum sunlight but do not interfere with operation of the vessel. 

Bottom: Something as simple as the shadow of a line or shroud can reduce or halt output.

Types of panels

Solar panels contain photovoltaic cells – small silicon semiconductor devices that convert sunlight into electricity. Each cell generates between 0.45 and 0.5 volts, depending on exposure to direct sunlight. Cell size determines amperage, with a 3-inch cell producing roughly 2 amps, a 4-inch cell a little over 3 amps, and a 5-inch cell around 5 amps.

Construction-wise, the three main types of solar panels are monocrystalline, polycrystalline, and amorphous (or thin-film) technology.

Monocrystalline panels have been around the longest and remain the most popular. The panels are constructed of thin slices of crystal silicon (each cell is cut from a single crystal) housed in a rigid, aluminum frame and covered with tempered shatterproof glass. The panels have a uniform black, blue, or gray appearance and are generally quite rugged, although they can be cracked or broken if subjected to extreme abuse.

Monocrystalline panels have the longest service life of the three types. With a conversion efficiency of around 17%, they’re also the most efficient and have the highest electrical output per area, but they are also the most expensive.

Polycrystalline cells are sliced from a cast silicon block and have a shattered glass appearance. Built in much the same way as monocrystalline panels, they’re rectangular, giving the panel itself a tiled look. Their life span is similar to monocrystalline panels, and while their conversion efficiency is lower (by 14%), they’re also a bit less expensive.

Amorphous panels are made by placing a thin film of active silicon on a solid or flexible backing (such as stainless or aluminum sheeting) depending on whether the panel is to be rigid-framed and glass-fronted or flexible. Flexible amorphous panels, in which cells are sandwiched between rubber and polymer covers, are light and tough enough that you can walk on them and, in some cases, even roll them up for storage.

This type of solar panel is also better if shade is an issue. With crystalline panels, even the thin shadow of a rope or shroud across one cell can reduce or halt output of an entire module. Amorphous panels have “bypass” diodes that essentially turn off shaded cells and provide a current path around them. Some monocrystalline panels also have bypass diodes, but this feature comes at an increase in cost.

Amorphous panels are the least expensive of the three types, but their efficiency is also lower – around 8%, or roughly half that of a monocrystalline type. This lower output is somewhat mitigated in newer panels, however, which use three-layer construction. Each layer absorbs different colors of the solar spectrum, so the panel will deliver more power longer each day and during lower light conditions than the other two types.

The charge controller should be mounted below decks and as close to the battery as possible. 

Follow manufacturer instructions for wire connections.

Planning the system

While factors such as cost, mounting options, and output are important, a successful installation depends on knowing what you want the system to accomplish. Is the goal to float-charge a single battery or supplement an overall vessel energy plan? Answering these questions up front will help determine the type, size, and number of panels required.

To understand the process better, let’s walk through the basic steps to determine power requirements and installation considerations for a single solar panel installation. While the example itself is simple, the steps are the same used to plan more complicated installations.

For our example, the goal is to install a solar panel to provide charging for a single 12-volt, 100-amp-hour wet-cell battery used to power an automatic anchor light on a moored vessel.

The first step is compiling a daily power consumption estimate to determine how much solar power is needed.

The daily self-discharge rate for a wet-cell battery is roughly 1%, meaning our 100-amp-hour battery requires one amp every 24 hours just to maintain the status quo. The anchor light draws 50 milliamps per hour of operation, and we’ll assume it operates 10 hours each night. Multiplying current draw (50 milliamps) by hours of daily operation (10) generates a daily energy expense of 500 milliamps or .5 amps.

This means our solar panel must meet a minimum daily energy tab of 1.5 amps – one amp of battery self-discharge rate plus .5 amps of power draw for the anchor light.

Next up is figuring out panel size and the best mounting location. For our example, let’s assume the panel will be a horizontal, fixed-mount installation. A 10-watt horizontally mounted panel should generate between 3- and 5-amp hours per day.

We’ll need at least 13 volts to fully charge our 12-volt battery. As most solar cells generate at least 0.45 volts, you’ll want a panel with a minimum of 33 cells, which should provide around 14.85 volts.

Keep in mind that’s the minimum needed, which may not be enough once you factor in a few cloudy days. Most panels are designed to generate between 15 and 20 volts to overcome problems like cloudy days or inherent electrical resistance within the panel or installation components. While this higher voltage lets you make up for less electrically productive days, it also means you’ll want to install a solar charge controller (voltage regulator) to avoid battery damage due to overcharging.

Attempts to plan a system that tries to use the output of the panel and capacity of the battery to prevent overcharging (and avoid the installation of a charge controller) is false economy and should not be done. The system will never meet its full output potential and, worst case, can damage the battery due to overcharging.

A word on ‘charge controller confliction’

If your vessel has multiple charging sources, such as solar panels and a wind turbine, a crucial but often overlooked consideration is “charge controller confliction.” In short, this is an issue where the charge controller for your solar panel and the charge controller for your wind turbine are internally adjusted to the same maximum charge voltage set point. This means they are constantly fighting each other to be the dominant power source, which results in diminished overall charging output and performance. An in-depth article on this issue can be found at ­missioncriticalenergy.com (in the website footer, click “Superwind Turbine Manuals & Technical Bulletins.” Under the header “Charge Controllers,” select the document “Resolving Charge Controller Confliction”).

While this article addresses charge controller confliction at remote, off-grid sites, the information provided is also applicable to vessel installations. — F.L.

Location and mounting

Solar panels should be mounted in a location where they are exposed to the maximum amount of sunlight but do not interfere with operation of the vessel or the movement of passengers and crew. Solar panels will typically be either fixed or mounted on some type of movable bracket that allows you to actively point the panel toward the sun for maximum output. Both methods have their pros and cons. Fixed panels (which are normally mounted horizontally) don’t produce as much power as a panel that can be adjusted to face the sun. The downside is that adjustable panels must be aimed throughout the day to maximize their output.

Use good quality, marine-grade heat shrink connectors (top) and liquid electrical tape (right) to create airtight, waterproof seals and reduce corrosion.

Installation

After choosing and mounting your panel, it’s time to connect it. The first thing you need to determine is the size (gauge) of the wiring to be used. Multiply your panel’s rated amp output by 1.25 (which adds a 25% safety factor). Then measure the length of the entire wiring run, panel to battery, and multiply by 2. Once you have these two numbers, refer to the American Boat and Yacht Council’s (ABYC) 3% voltage-drop table for wire size. Ancor Products offers a handy wire calculator on its website ( ancorproducts.com/resources ).

Always use good quality marine grade connectors  and tinned, multi-stranded copper wire with vinyl sheathing. The wire will run from the solar panel to the charge controller first, then to the battery. Try to keep the wire run as short as possible, and if it transits an external deck or cabin house (it likely will), be sure to use an appropriate weatherproof deck fitting.

The charge controller should be mounted below decks and as close to the battery as possible. You’ll always want to follow the manufacturer’s instructions for connections, but in a typical installation you’ll connect the solar panel’s positive (red wire) lead to the charge controller’s positive input wire or terminal and the negative (black wire) lead to the charge controller’s negative input wire or terminal.

Next, connect the charge controller’s negative output to the battery negative terminal and the controller’s positive output to the battery’s positive terminal via an appropriately sized in-line fuse (or circuit breaker). ABYC recommends these be installed within 7 inches of connection to the battery or other point in the DC system. To reiterate, the installation of the charge controller can vary among models, so follow the manufacturer’s installation instructions.

Finally, ensure all connections are waterproof and secure any loose wire runs with wire ties and cable clamps for a neat installation. Then get ready to lean back and soak up some free sun.

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Frank Lanier

Contributing Editor, BoatUS Magazine

Capt. Frank Lanier is a SAMS Accredited Marine Surveyor with more than 40 years of experience in the marine and diving industries. He’s also an author, public speaker, and multiple award-winning journalist whose articles on boat maintenance, repair, and seamanship appear regularly in numerous marine publications worldwide. He can be reached via his YouTube channel “Everything Boats with Capt. Frank Lanier” and website captfklanier.com.

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Sailboat Life

Sailboat Cruising and Lifestyle Magazine.

Sailboat Solar Systems and How-To

Solar on a sailboat goes together like hands and gloves, but sailboat solar systems can be installed in a variety of ways. The solar components themselves create an infinite combination of possibilities for off-grid sailing. Victron Energy chargers, Renogy Panels, Sunpower Yachts, BlueSea Systems, and many more brands have entered the marketplace, and that’s not including the lithium battery companies.

To simplify things, we’ve compiled three sailboat solar systems videos to give you an overview of what’s possible. And to help you decide on your own simple solar panel setup for sailing.

How-To Install Solar Panels on Your Sailboat

This system from Zingaro shows flexible panels summing 300w of power on a 38′ catamaran.

300W Solar System:

• Three 100w solar flexible panels
• 1 MPPT Solar charger controller

View on Amazon >>

100W HQST Flexible Solar Panels $100-$200

20amp Solar Charge Controller by Victron Energy $150-$200

Simple Sunpower Solar System

This simple solar system from The Fosters shows a quick and easy setup with limited space on top of a bimini.

Sunpower Solar Panels are considered by most in the industry as the gold standard. They use the highest-efficiency solar cells and have top-notch build quality. In this simple installation, three 50w panels are just enough to get you started. Plus, it’s the most affordable installation!

150w Starter Solar System

• Three 50w Flexible Solar Panels
• A Single 15amp solar charge controller

50W Sunpower Solar Panels $150-$200

75v/15amp Solar Charge Controller by Victron Energy $100-$124

Off-Grid on a DIY Solar Powered Sailboat

Here’s a special installation that turned a derelict sailboat into an off-grid sailing machine!

Simon has transformed this derelict sailboat into an epic off-grid solar-powered and fossil-fuel-free cruising catamaran. He’s been living aboard and renovating the boat for the past 3.5 years We’re excited to show you the transformation as well as how he plans to propel the boat without the use of diesel or fossil fuels!

5280w Solar System for Electric Powered Catamaran

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Yachting Monthly

• Digital edition

Sailing with solar power: A practical guide

• Duncan Kent
• November 13, 2020

The latest solar technology makes self-sufficient cruising much more achievable. Duncan Kent gives the lowdown on everything you need to get your boat sorted

SOLAR POWER ON BOARD

Solar power is fast becoming the most popular and economic method of keeping the batteries charged on a boat.

Particularly now that the efficiency of photovoltaic (PV) panels, charge controllers and batteries is improving every day.

Furthermore, the latest technology in regulators and charge controllers has brought about a noticeable increase in useable power output, so the problems of shading and non-alignment can be compensated for more easily.

Not only has PV equipment become more efficient and cost-effective, but many of the modern devices we want to use on a boat have become less power hungry.

This means it is now far easier to provide your entire yacht’s electrical needs, both 220Vac and 12/24Vdc, from natural energy resources – particularly solar power, even if you are planning on a fully electric boat .

Thinking carefully about how much power you need and how much your boat can accommodate is key to planning a solar array. Credit: Graham Snook

WHAT DO YOU NEED?

For instance, a boat with two new, good quality, deep-cycle house batteries of 100Ah each would supply 100Ah of energy to consume between charges, if you only use the recommended 50% of available charge between each charge cycle to protect the batteries.

From this you could run:

• a modern 12Vdc fridge (approx. 1.5Ah, or 36Ah over 24hrs),
• all LED lighting (say 20Ah per day),
• various small device chargers (20Ah)
• and a number of other items such as water pumps, TVs and stereos (25Ah/day)
• Totalling around 100Ah.
• For this you’d need 400W of solar capacity.

Of course, if you like to run a lot of AC devices off-grid such as hair dryers, microwaves, toasters and the like, then you’re going to need a DC/ AC inverter, which will take you to another level in power consumption terms.

But even then, with careful planning, solar could provide a large portion of the power you need before resorting to engine charging or a generator.

THE AVAILABLE SPACE

In practical terms, a modern 40ft monohull would have the space for around 1,200W of PV panels (cockpit arch, sprayhood top, deck), maybe 1,500W with the addition of a few portable panels for use at anchor.

The 1,200W of fixed position solar array could produce around 360Ah on a sunny summer’s day (zero shading) or more likely 250Ah on the average UK summer’s day.

So that’s enough for your 100Ah general DC consumption plus another 150Ah of AC consumption via the inverter.

Of course, to do this you’ll most likely need to increase your battery capacity to around 400-500Ah for maximum flexibility (you’ll need to store as much as possible during daylight hours), a typical figure for a 40-50ft offshore cruising yacht these days.

Get your solar charging right and you may never need to hook up to shore power

Typical daily inverter loads for a cruising yacht off grid might be:

• induction cooking plate (20min) 60Ah
• microwave (15min) 30Ah
• coffee maker (20mins) 25Ah
• hair dryer (5min) 15Ah
• laptop charger (2h) 10Ah
• or around 140Ah in total.

The trick is to monitor the batteries’ state of charge (SOC) at all times and vary your use of the inverter to suit.

For example, you might want to cook supper mid-afternoon, when solar is in abundance, and then reheat it in the evening when you want to eat it.

In some cases, when you’re cruising in warm climates such as the Med, you might end up with excess charge from your solar panels .

In this situation, many long-term cruisers devise a method of ‘dumping’ the extra energy by heating water for showers.

Do bear in mind if you’re planning to live aboard full time , then it’ll be a whole different story on cloudy days and during the winter, when inverter use might need to be knocked on the head entirely.

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POWER DISCREPANCIES

There’s often confusion as to how much power you can harvest from a solar installation.

A PV panel is nearly always advertised stating its theoretical peak output power (Pw).

But in reality, on a yacht where there are limited areas in which to mount them, they will more likely produce a maximum of 60% of their peak output if mounted horizontally, increasing to 80% if tilted towards the sun and regularly adjusted.

The latter is rarely achievable on a boat, however, as even at anchor it can swing through an arc of 180° in wind or tidal shifts .

Flexible panels can be mounted on sprayhoods or awnings to add power when it’s needed at anchor or in harbour

INSTALLATION

Having trawled through hundreds of ‘deals’ to get the best price on the most efficient panels you can afford you now need to know how to install them to best fulfill your energy generation needs.

The output, even from the highest quality photo-voltaic array, will only be as good as the installation itself.

So following our guidelines should ensure you extract every last drop of energy from your investment.

PANEL MOUNTING

Sailing boats are not the ideal structure on which to mount wide, flat PV panels.

So before you go ahead and purchase what looks like the biggest and best, take a few minutes to decide on exactly where you can mount them, as this will affect what size and type of panels you should buy.

In many cases the first choice would be on an arch, davits or gantry aft, especially if you already have, or plan to fit one.

Dinghy davits, particularly on multihulls, can support a huge solar capacity

These allow a solid metal framework to be constructed that will be strong enough to take the heavier, more productive rigid PV panels.

You can also build in some form of adjuster to the framework that will allow the panels to be orientated towards the sun for the best performance.

With luck (or careful planning) a gantry will also keep them aft of the boom, thereby eliminating loss of output caused by boom shading.

The next most popular position for mounting the panels is on a cockpit sprayhood or bimini, although this will often mean using the flexible or semi-flexible panels, which are generally less efficient than the rigid ones for the same area.

ELEVATED MOUNTING

Alternatively, there are kits available for mounting panels onto lifelines, which can allow their elevation to be manually adjusted to a certain degree.

Pole-mounted panels can be used for maximum adjustability

Finally, panels can be fitted directly onto the deck by either gluing them down using mastic or attaching them onto a rigid support frame.

Once again you will probably need to use semi-flexible panels – especially if the deck surface is curved.

Rigid, glass-coated panels will obviously not be suitable for deck mounting in an area that is frequently walked over.

Don’t be tempted to drill through the panels, even along the edges, as this will invalidate the warranty and possibly damage the panel.

With solid panels, the ability to adjust the angle can add significantly to output

It might seem obvious, but the key to an efficient system is to avoid shading wherever possible.

It’s no good fitting expensive, high-efficiency PVs right under the boom as they’ll perform little better than the cheaper types.

Saying that, in good quality panels each cell will be isolated from the next by a series of diodes (one-way electrical valves), so that if one cell is shaded at least it won’t drag down the other cells within the same panel.

Older panels often didn’t have these, so the slightest partial shading caused the output of the entire panel to cease.

OVERHEATING

Another important factor that is often ignored when installing the panels is that of overheating.

If a PV panel gets too hot, which is quite likely if mounted directly onto a flat surface without an air gap behind, its output will drop quite noticeably.

To allow for some air circulation behind the panels it’s best to apply mastic adhesive in numerous large dabs.

This is best achieved by placing wooden spacer strips between the dabs until the mastic has completely cured, after which the spacers can be removed.

You might need some form of trim around one or more of the outside edges, though, if they are positioned where sheets and other lines might get caught under them.

Raising the panels up will also help water to drain off and thereby helping to avoid possible delamination from sitting in water for too long.

CHARGE CONTROL

A PV module cannot supply an electrical device directly due to the changeability of the sunlight, which in turns varies the current it can produce.

Therefore, it has to be connected to a battery, which stores and smooths its output.

Whatever the size of your solar array you will need to fit a regulator, or charge controller as they are now more commonly known, to the system in order to control the output and to help extract as much power from the panels as possible.

There are two types of PV charge controller.

The older designs, called Pulse Width Modulation (PWM) types, were fairly basic voltage regulators and simply output volts at just above battery level.

The latest controllers use Multi Power Point Tracking (MPPT) technology and can accept much higher input voltages (up to 240Vdc).

MPPT controllers can be up to 30% more efficient as they use the peak output of the panels to charge the batteries, even compensating for partial shading.

BEWARE FAKE GEAR

If you buy online do be careful to ensure you’re getting what you pay for.

There are a huge number of fake MPPTs out there, which are simply the much cheaper PWM dressed up with fake labels.

It’s hard to tell which is which, but the old adage of ‘if it looks too good to be true, it usually is’ makes good sense.

MPPT controllers are usually bigger and heavier than PWMs, but if in doubt call or email the supplier to discuss the pros and cons of their kit before buying.

If they’re not happy to chat and advise you then I would steer clear of their gear.

Some good MPPTs are made in China, but unless they have a UK supplier, I wouldn’t bother with them as you’ll have no follow-up advice.

To calculate what size controller you need simply divide the panel’s peak power in Watts (Wp) by the battery voltage, which will give you the maximum current (Amps) they could theoretically supply.

For example 240W/12V = 20A. Although it’s unlikely you’ll ever get near the peak output from any PV panel, it’s best to go for the maximum possible.

Induction cooking is now a reality on board, even without shore power

PV panels come with a short length of cable, usually around 1m long.

Some are supplied with MC4 connectors already attached but most only provide bare wires.

The latter can be easily extended using proper waterproof connections but thought must be given as to the current rating and voltage drop (usually max 3%) for the size of cable you intend to use.

If in doubt, bigger is better!

Panels can sometimes be ordered with the wiring on the back so that the cable can go straight below deck through a hole under the panel.

You may need to fit extra battery capacity if you want to run an inverter from solar charging

SERIES OR PARALLEL?

A commonly asked question is ‘should I wire my PV panels in series or in parallel?’

The simple answer is, if there’s any danger of frequent shading to one or more of the panels then install them in parallel.

If wired in series the shading of a single panel will drag down the output from all of the others in the same series.

PARALLEL IS PREFERRED

Most commonly, multiple panels are wired together in parallel to a single charge controller, with diodes protecting each panel from discharging the others should one become partially shaded.

With the advent of MPPT controllers, however, there can sometimes be a benefit to wiring two or more identical panels into a series bank, thereby presenting a higher voltage to the controller.

It’s worth noting that, like batteries, wiring PV panels in series increases the voltage only – the current capacity of the array remains the same as for a single panel.

‘Where’s the benefit of wiring them in series then?’ you might ask.

Well, the higher the voltage fed into the MPPT, the more consistent it will be with its output, which could, in some cases, prove more efficient than a parallel installation with PWM controllers.

It’s also likely to be necessary if you have a 24V domestic system.

SERIES WIRING

Series wiring is usually only done when the cable runs are long, as it helps negate the voltage drop caused by the resistance of the cable.

While a decent controller will have no problem handling the output from four or even five panels wired in series, it is often inappropriate for sailing yachts as shading just one of the panels will reduce the output of the entire series array.

If you need to do so in order to reduce cable runs then it’s best to split the panels between each side of the boat – a series bank on each side.

If you do this, then you would ideally fit a separate controller to each series PV bank and then connect their outputs together in parallel to the battery bank.

Note, however, that panels wired in series must all be the same types with an equal number of cells per panel.

Furthermore, the charge controller needs to be sized for the total of all panel voltages added together and the current rating of one individual panel.

Differently rated panels can be connected together in parallel but only if each panel has its own controller.

The outputs of the individual controllers can then be joined together to go to the battery bank.

BATTERY BANK QUESTION

Another frequently asked question is ‘Can I connect another charging source to the battery bank while the solar array is charging?’

The answer is yes.

Any decent PV controller will be protected against feedback from other charging sources.

Think carefully about where shade from mast, boom and rigging will fall. Credit: Graham Snook Photography

CABLE SIZE AND CONNECTORS

A frequent cause of reduced output from PV arrays is wiring that is too small.

The resistance of a wire conductor increases in direct proportion to its cross-sectional area, so go as big as is practicable for the least cable loss.

Each panel should be supplied with the correctly sized cables for its own maximum output.

But if you’re combining panels, either in parallel or in series, you will clearly need to rate the single feed cable to suit the maximum current available at theoretical peak solar output and to minimise voltage drop.

Likewise, the cable from the controller to the batteries should be sized to suit the controller’s maximum output current and protected with a fuse.

For outside it’s important to use exterior grade cable, which is double- insulated and UV-proof.

WEATHERPROOF CONNECTORS

And wherever possible use compatible weatherproof connectors (usually MC4) to those found on the panels rather than cutting off the plugs and hard-wiring them.

Field- assembly MC4 plugs are available, so you don’t have to drill large holes in the decks or bulkheads when feeding the cables through.

When joining more than one panel together try to use the approved multiway connectors; not only do they keep the wiring neat and tidy, but they also offer a greater contact area than budget terminal blocks.

If you have to use screw-type connectors make sure to fit proper ferrules to the wire first to avoid any stray wires in the multistrand shorting across the terminals.

When feeding a cable from above to below deck, try to go through an upright bulkhead where possible to minimise ‘pooling’ of water around the access hole.

Also, use a proper watertight deck seal that matches the cable you’re using.

If drilling through a cored deck you need to drill a larger hole first, fill it with epoxy resin and then drill the required size hole through the epoxy to ensure no water gets into the deck core.

Ideally, the charge controller should be mounted no further than 2m from the battery bank.

If you need to go further, you’ll require larger cabling to reduce the voltage drop.

A generous solar array will keep you self- sufficient indefinitely. Credit: Graham Snook Photography

CONTROLLER LOAD TERMINALS

There is often confusion over the ‘load’ output of a charge controller (often depicted by a light bulb) and what can safely be connected to these terminals.

Rarely explained in the manual, the load terminals should be pretty much ignored in a marine installation as the output on these terminals is usually very limited (10A max).

Some attach an LED light to them to indicate the controller is operating, but all your usual electrical loads should remain connected to the batteries with the battery terminals on the controller connected directly to that battery bank via a fuse.

It is possible, though, to control a high-current switching relay in certain conditions.

Parallel installation is more resilient to shading, but a series installation will increase peak charging outputs. A combination of the two offers some of the benefit of both

CIRCUIT MONITORING

Unlike most cheap PWMs, the majority of good quality MPPT charge controllers come with an alphanumeric LCD screen to let you know what is going on.

This can either be a remote display or simply one on the front of the box.

It’s obviously a lot better to have a proper numerical display than to rely on a few flashing LEDs to tell you when something’s not right.

So if your chosen controller doesn’t have one be sure to fit a battery monitor (the shunt type) into your solar circuit between the controller and the batteries.

It doesn’t have to be a very ‘smart’ monitor, just one that can display the voltage and current being supplied by the panels.

For smartphone addicts there are several wifi apps that will do the job remotely on your phone or tablet.

DEVICE PROTECTION

All good quality PV panels feature built-in diode protection between each cell to prevent a shaded cell from dragging down the productive ones.

In addition, there will be internal blocking diodes on the final output to protect the panel from polarity reversal and to ensure that the batteries can’t discharge back into the panel during the night.

The latter can be added externally, the former can’t, so check before you buy.

A fuse, rated just above the maximum current available, should be fitted between each panel and the charge controller.

Another fuse should then be installed between the charge controller’s output and the batteries.

In the case of multiple arrays, this second fuse will be rated higher than the individual panel fuses and should match the maximum current rating of the cable.

With this protection installed other charging devices can be connected in parallel at the battery, meaning the solar can be left connected even when you are hooked up to shore power and the battery charger is operating.

In some circumstances, however, this arrangement can affect the sensing of the battery by the charger, causing it to fall back into float mode.

If this becomes apparent it can be overcome by installing a manual/auto switch to disconnect the solar array when on shore power.

Check the flex of the solar panel is sufficient for your deck

EXCESS POWER DUMPING

A solar charge controller works by disconnecting the supply from the PV panels when the batteries are fully charged.

But for some full-time liveaboards in sunny climates that can be considered a waste, when the excess power could be put to good use – heating water, say.

This is commonly done using an inverter to supply AC power to the heating element.

Alternatively, you can now buy a 12Vdc element for your calorifier (hot water tank) and supply this directly from your battery bank.

Both of these methods would require a voltage sensitive relay (VSR) to disconnect the element should the battery voltage drop below a pre-set level.

Don’t expect boiling hot water, as there will probably only be enough spare power to take the chill off it before your battery bank reaches its lower threshold voltage.

A 600W/12V element will draw some 50A, from the batteries, whereas a 1kW AC element run through an inverter will need close to 100A.

A small, semi-flexible panel will be sufficient for keeping batteries trickle charged, but not for heavy use

RIGID, FLEXIBLE, OR SEMI FLEXIBLE?

Despite massive recent improvements in semi-flexible panels in recent years, the solid glass panels still offer a higher power density.

That said, they are heavier, more awkward to mount and can’t be walked on, so unless you have a dedicated gantry aft, you’re better off choosing the more rugged semi-flexibles.

Modules incorporating monocrystalline cells also have a better output than those with polycrystalline cells (that’s cells made from a single slice of silicon as opposed to layers of smaller pieces).

Output voltage also depends on the number of cells on the panel.

In the past this has commonly been 32, but now some 36 and even 40 cell panels are available.

That said, they’re larger, of course, so an array of interconnected smaller panels might be a better solution.

Module efficiency is now more often around the 20% mark, as opposed to 12-15% for older models and semi- flexible (up to 20° bend) are usually better than flexible (up to 180° bend).

A rigid panel is more efficient, but less robust

There are a huge number of panels on the market, but many use the same cells.

Sunpower Maxeon cells are exceptionally good, as are the Panasonic HIT range and LG, but they are pricey.

If the maker is offering a 25-year guarantee instead of a 3-5 year one, you can be pretty confident they’re good.

When it comes to charge controllers it’s definitely worth paying a little more for a decent MPPT.

A cheap PWM might be okay just to keep a small starter battery charged with a 30W panel, but the MPPT will give you much more when it comes to heavy service.

Victron are probably top of the range, while cheaper brands like MakeSkyBlue and EPever are also good value – but treat imports of unclear origin with care.

ABOUT THE AUTHOR

Duncan Kent has been evaluating and reviewing yachts and marine equipment for the past 30 years

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Top 3 Best Solar Panels For Sailboats

Last Updated by

Daniel Wade

June 15, 2022

Choosing whether or not to install solar panels on your sailboat is a big decision. They are not exactly cheap, though they can start to pay themselves off pretty quickly.

This article is going to cover not only why you might want to use solar panels but all the benefits they provide. You will also find a helpful guide on which solar panels would be best for you and your budget. Hopefully, by the end, you will feel confident in your decision to install solar panels on your sailboat and even have an idea of which ones you might like.

Table of contents

Are solar panels on sailboats necessary?

Whether or not you should be installing solar panels on your boat is a matter of choice, not out of necessity. Sailboats get their power from the wind, by harnassing it in their sail. So if you plan to be sailing for the afternoon you probably don’t need solar panels.

You could charge a battery pack from the marina and that will probably see you through several trips. The problems only really start to arise if you are planning to be on your sailboat for longer periods, or even permanently. If you plan to live on your sailboat year-round, even if you spend 80% of it in a marina, you would be better off with some solar panels. Even if it is just as a backup source of power.

Are solar panels on boats safe?

Solar panels are generally pretty safe. They have no moving parts and typically have a very strong protective cover over them so you never come in contact with the electrics themself. So, as a source of power, they are generally pretty safe. The only time they may become unsafe is if they are badly damaged.

Solar panels are often covered by glass plating that keeps them safe. It also helps them absorb sunlight and warmth. This is great, except when the glass breaks. If the glass protective cover on your solar panels should crack and splinter you are at risk of serious injury from sharp shards of glass. Not only is the glass itself dangerous at this point, so are the electronic components inside. They have powerful currents running through them, and if you come in contact with them you may be in for a shock.

Furthermore, if these electronics get wet they can become deadly. Electricity and water do not mix well at all. Being as you are on a sailboat, at sea, the chances of them getting wet is very high. Luckily, the chances of them breaking in the first place are slim to none. The only real way they would break, besides vandalism, is by debris hitting them during a bad storm. There is not often debris at sea, so this shouldn’t be too much of a problem.

What are the benefits of having solar panels on a sailboat?

There are so many great benefits of having solar panels on a sailboat. They can be a lifesaver if you find yourself at sea for a long time. There benefits range from trivial comforts to being the difference between life and death. Here are some of the benefits you might not have considered about having solar panels installed on your sailboat.

Money-saving

Solar panels are not cheap, it is far cheaper to just run a generator or charge your batteries from the marina the whole time. At least, it is in the short term. Over time, it can start to become very expensive. With solar panels, you are looking at a big initial cost (the solar panels themself) and then it’s smooth sailing. You don’t need to pay for power again. Solar panels last for about 40 years before they start to become too inefficient at producing power. The cost of a few solar panels upfront compared to 40 years of marina fees and gasoline for a generator is the financially savvy move.

Emergency power

If you find yourself at sea, the wind dies down (or becomes too strong), and you find yourself stuck bobbing around waiting for more favorable conditions you may run into trouble. Depending on how long you are out there, you may find yourself with dead electronics. Be it a satellite phone, radio, or secondary engine (depending on the boat). Having a set of solar panels and a power bank can be a genuine lifesaver in these situations.

Comfort amenities

Whether you are day sailing or making a week-long voyage, having access to the comforts in life can make the whole journey so much more enjoyable. The amenities may not be available to you without having a constant source of power at sea. Having access to a kettle, tv, videogame system, radio or microwave oven may be the only thing keeping you going at rougher times. As exciting as sailing can be, when you aren’t sailing and are just bobbing around it can be quite dull. The sea is beautiful, but there is only so much time you can spend looking at the water before you miss the comforts of land. With solar panels, you can bring those comforts with you.

Eco-friendly

There are only two alternatives to solar panels. A gasoline generator, and taking power from the grid. Neither of these is good for the environment. Luckily, solar panels are a great third option. Solar panels are completely eco-friendly and are great for the environment. This is not just great for the earth, and your conscience, but for the journey itself. If you are running a gasoline generator at sea you are going to be listening to it thrumming away and smell the burning gasoline. Wouldnt you prefer silence and nothing but the smell of the sea breeze?

How much do solar panels cost?

How much solar panels cost is almost entirely tied into both their voltage/wattage and whether or not they are portable panels. Portable solar panels are great for people who don’t spend a lot of time on their boat or are happy enough living off the marina’s power grid. Permanent solar panels, the kind that may need to professionally installed, can end up costing far more. They are also likely to be far superior and you can pretty much forget about them once they are installed.

Portable solar panels will cost just a few hundred dollars each. You will need a few to be sustainable, but that’s not going to be much of a problem. These portable solar panels can just be rolled out on the deck of your boat, weighed down, and then hooked up to a battery pack. The battery itself here is going to be the most expensive part of the whole set up. A decent-sized battery could set you back a $1000. But, when charged fully it will last days. Even with constant use.

Permanently installed solar panels can cost one or two thousand dollars in some cases. The advantage here though is once they are installed that’s it, you can forget about them. You don’t have to put them up, take them down, and find somewhere to stow them every time they need using. They too will need to be hooked up to a battery, the battery is still only going to cost you $1000. If you are installing permanent solar panels because you plan to be making long voyages, it is ideal to have two or perhaps even three large batteries hooked up to your boat. One to run off, one or two for emergencies.

How do I maintain my solar panels?

Solar panels, unlike gasoline generators, are generally pretty easy to maintain. They have no moving parts and are thus pretty self-sufficient. They don’t need taking apart and they last as long as 40 years. That being said, if they do break they need repairing as soon as possible. The exposed electrics can be deadly when water is thrown into the mix. Which, on a boat, is almost always. The glass cover will need replacing and the electronics inside may need repairing, though not always. Don’t ever attempt to do this yourself unless you are experienced at making these repairs. The cost of hiring someone to do it for you is preferable to being dead. Solar panels have very powerful electric currents, that when in contact with water and yourself can be fatal. As mentioned above, these panels rarely break so you will likely not ever run into this problem. If you do, hire a contractor.

Do my solar panels need cleaning?

Solar panels work by converting the light and heat of the sun into useable power. The process itself is rather complicated but the results are simple to understand. That being said, there are some reasons that your solar panels will stop working as effectively. They all revolve around a lack of sunlight. It could be because it is night time. It could be because it is very cloudy. Or, it could be because they are dirty. If solar panels become too dusty, dirty, and become too covered in grime they stop operating at maximum efficiency. This is not as much of a problem at sea, the sea spray stops dust settling. The biggest thing you will need to clean off your solar panels is salt build-up and slime. This is easy enough to do with some warm soapy water. Freshwater, not seawater. You want to be removing as much salt as possible. Salt is corrosive to electronics, so removing it is important. Never clean your solar panels using pressure washers as they can crack the glass.

Which are the best solar panels for sailing?

There are so many options on the market at various price points. Here are three very different options that will all make good choices, depending on your needs. It is important to consider not just price but power output. Spending a lot of money on solar panels now might not feel ideal, but it is the most cost-effective decision.

1. Renogy Starter Kit

This starter kit is going to be perfect for installing on almost any sized boat. There are four solar panels, each can be fitted permanently to the boat. They can be mounted (and unmounted) easily, for your convenience. They do require a flat surface, but they are small enough that that likely won’t be too much of a problem. This starter kit is very middle of the pack price-wise but should provide enough power for a small to medium-sized vessel easily. It is also possible to buy extra panels individually should you need them.

Wattage: 400/4 (100 per panel)

2. Nature Power Rigid

The nature power rigid is a large, powerful, single solar panel. If you are looking for the right panels to power your entire boat comfortably, these are the ones for you. They are very large so they will need a large flat surface area. alternatively, they can be hung vertically from rails. This is an inefficient way of using them, so you would need to buy more this way. Nature power makes various solar panels so you could find some smaller ones of the same brand to supplement it. This one is not so easy to install, you might need to hire someone to install it for you.

Wattage: 165

3. Nature Power Monocrystalline

Nature power makes a portable solar panel that fits inside a special briefcase. It is perfect for stowing away easily and only taking it out when it is needed. It is decently powerful considering its portable, but there is the inconvenience factor of having to set it up each time. If you planned to buy the nature power rigid, buying one of these portable panels might be ideal for supplementing your power supply when it is especially sunny. Though, it may be cheaper for you to just fit more of the Nature Power Rigids.

Wattage: 120

Hopefully, you now have a good idea about whether solar panels would be right for you and your sailboat. Sailing is great, but the lack of power at sea can be dreadfully boring. Luckily, there are so many great options available on the market. Not just the ones mentioned above. Buying a solar panel is an investment, the initial cost is minor compared to the steady return from all the savings you will make.

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I've personally had thousands of questions about sailing and sailboats over the years. As I learn and experience sailing, and the community, I share the answers that work and make sense to me, here on Life of Sailing.

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Sailboat Solar Panel Installation

Table of Contents

Using solar panels for maritime purposes, installing solar panels on a boat, positioning your solar panel, wiring your solar panels, cabling and connector considerations, choosing a charge controller, maintenance and general upkeep.

In recent years, the concept of solar energy has taken the world and, specifically, the maritime industry by storm.

Installing solar panels on a boat has become common practice within the maritime community as solar panels charge your boat’s batteries in little to no time thanks to the amount of sunlight they enjoy. Not only are solar panels both effective and affordable, but they’re an environmentally-friendly alternative source of power.

In this article, we guide you through the process of installing solar panels on a boat, providing you with a checklist of all the factors you’ll need to consider to ensure that your solar panels have the highest power output possible

Before we dive into the intricacies of the installation process, it’s important that we take a quick look at why you should install solar panels on your sailboat as well as how to determine which solar panels to use.

Why is Solar Power Useful on a Sailboat?

When it comes to sailboats, a common misconception is that the only energy that sailboats use is the kinetic energy of the wind to move it forward. 

This is obviously not true because there are a number of systems on a sailboat that all require battery power. Some of the things requiring electrical power include:

• The rotor for when there is no wind to propel the sailboat forward
• The autopilot feature on newer, more advanced sailboats
• Navigation lights
• Radio systems

For this reason, most sailboats also have built-in batteries to power all these systems. It is here where the usefulness of solar power comes into play.

By installing solar panels on your sailboat and connecting them to this battery, you’ll be able to recharge the battery of your sailboat using sunlight on a daily basis. This means that you’ll never run the risk of ending up in the middle of the ocean and at the will of a flat battery.

Choosing the Right Solar Panel

As you’ll see further below, choosing the correct solar panel for your purposes will be determined by a number of factors.

You’ll determine the size of the solar panels you used based on the amount of space you have available to you for the purposes of solar panel installation. The size of your sailboat is obviously a major determining factor in this regard.

Looking at the power requirements of your specific sailboat will also help you determine how many and which type of solar panel will be the best to satisfy the power needs of your sailboat.

Finally, the specific form of solar panel you’ll need to use will depend on where you intend to install your solar panels. As we’ll discuss later, on some occasions rigid solar panels will be the best panels for the job, but on other occasions you might find that flexible or semi-flexible solar panels are required for the specific installation site.

When it comes to addressing how to install solar panels off-grid on your sailboat, you’ll find that the process is one that has the potential to be rather lengthy and, sometimes even, tricky. For this reason we’ve put together a set of guidelines that should help you navigate these turbulent waters.

The first hurdle you’ll encounter when starting the process of mounting a solar panel on your sailboat is finding somewhere to mount it. This is because the decks of sailboats are not necessarily the most ideal of surfaces upon which to install your solar panels.

That being said, there are a number of commonly used areas that we would recommend you look at as your points of departure.

Arches or Gantry Aft

The first place we recommend positioning your solar panel is on one of the arches of your sailboat or on the gantry aft.

The effectiveness of this position is usually enhanced by the additional construction of an adjuster of sorts that’ll allow you to position your panel so that it receives as much sunlight as possible.

Cockpit Sprayhood or Bimini

This is generally regarded as the second most popular location in which to mount your solar panel.

For this location, we recommend using a flexible or, at least, semi-flexible solar panel instead of a rigid one.

The flexible solar panel we recommend in this regard is the Inergy Linx 100 Watt Flexible Solar Panel which is just one of the multiple solar panels of this type that we have in our immaculate inventory here at Shop Solar Kits.

The third alternative to the above two locations would be mounting your solar panel on the lifelines running alongside the cockpit. Here you would need to make use of the available installation kits that will allow you to turn and angle the panels manually to a limited extent.

Finally, the deck is also a commonly used location for the installation and mounting of solar panels on a sailboat.

Here you will need to consider the size and gradient of your deck. If you have a curved deck, you will once again need to make use of flexible or semi-flexible solar panels instead of rigid glass-coated panels. 

This link in the installation chain follows the above considerations that need to be made prior to mounting your solar panels.

When considering the location where your solar panels are going to be installed, you not only need to choose a location that offers the most available space for solar panel installation, but that is also the most practical for solar panel installation.

The two considerations that you need to bear in mind in this regard are shading and overheating

Shading                                              

One of the most important principles to remember when deciding on a surface on which to install your solar panels is to stay away from shade.

You want to position your solar panel in a position that receives as much sunlight as possible as this will in turn guarantee that your solar panel produces as much power as possible. That being said, sometimes the shade that is thrown by the boom, mast, or sails simply can’t be avoided.

For this reason, you want to ensure that you purchase high-quality solar panels. Modern solar panels are much less sensitive to partial shading as each of their solar cells is isolated from one another by one-way electric valves.

Therefore, if a couple of cells are shaded, they won’t have a negative impact on all the other non-shaded cells in the rest of the panel.

Overheating

If your solar panel overheats, it’ll take a massive knock to its overall power output.

To prevent this you’ll need to ensure that your solar panel has sufficient air circulation behind it, especially if it's installed on a flat surface like the deck.

With regards to these latter flat installations, you want to mount the panel to the deck with large dabs of mastic adhesive to promote better air circulation around the solar panel.

This step in the installation process addresses one of the most frequently asked questions by people installing solar panels on their boat for the first time: should they be wired in series or in parallel.

The answer to this question ties in with the issue of shading that was dealt with above. If shading is one of your largest concerns, you’ll want to have your solar panels wired in parallel and not in series.

You might remember from your early high school science classes that if the light bulbs in an electric circuit are connected in series, if one of the bulbs fails, all the other bulbs connected in series will also fail.

The same principle applies to solar panels. Firstly, if your solar panels are connected to each other in series, if one solar panel suffers any damage and becomes defective as a result, the rest of your solar panels will be affected negatively as well.

Similarly, if one of your solar panels is in the shade for more time than the rest of your solar panels, all of your solar panels’ productivity will be negatively impacted too.

However, if your solar panels are connected in parallel to each other, the malfunctioning or shading of one panel will not affect the overall power output of your other solar panels.

In this regard, there are two factors that you will need to consider: cable thickness, and cable and connector durability.

If you do not use the corrected sized wiring for your system, you’ll experience a significant reduction in the overall power output of your solar power system .

The thickness of the wire you’ll need to use is determined by how you want to wire your solar panels – in series or in parallel. If the former is your setup of choice we recommend using a thinner-gauge wire due to the fact that here, the voltage of the circuit is additive whilst the current flowing through it remains constant.

Conversely, if you want to wire your solar panels in parallel you’ll need to use a thicker-gauge wire due to the fact that here, the current flowing through the circuit is additive whereas the voltage remains constant.

This process is, however, slightly more complicated if you plan on mixing different wattage solar panels in your system. For this reason, it is important that you thoroughly calculate the voltage and current flowing through your circuit to ensure that you employ the correct use of wiring for your circuit.

Upon deciding on the thickness of the wiring you’ll be using, ensure that you use wiring that is weatherproof (meaning that it is exterior-grade wiring that is double insulated and UV-proof) as well as weatherproof connectors.

Failing to do this, you run a much higher risk of your circuit malfunctioning due to water or weather damage. By ensuring that your cables are highly-durable you’ll save yourself a lot of time, money, and effort in the long run.

Choosing the right charge controller for the size of the system you want to install is also an essential consideration in the process of installing solar panels on your sailboat.

The purpose of a charge controller is essentially just to disconnect your solar panels from your battery when it is fully charged. It’s also the solution to the dilemma of how to charge multiple batteries with one solar panel because, as its primary purpose is the managing of the charging of batteries.

That being said, we don’t recommend a setup using two charge controllers and one solar panel . This is because, to put it simply, it’s just unnecessary. 

One charge controller is more than sufficient to monitor the functioning of a single solar panel. The same isn’t true for multiple solar panels, however, where more than one charge controller could be useful where many solar panels are used.

There are generally two types of charge controllers for you to choose from: PWM (pulse width modulation) controllers; and MPPT (Maximum Power Point Tracking) controllers.

PWM Controllers

These are a fairly simple and inexpensive alternative to the more expensive and complicated MPPT controllers.

That being said, although these are much cheaper than MPPT controllers, they are also considered to be rather primitive in comparison with MPPT controllers.

MPPT Controllers

These controllers are much more advanced than PWM controllers. 

They allow you to achieve the optimum power output of your solar system by constantly tracking and logging the troughs and peaks of your system’s productivity and adapting the output of the system to the batteries you’re using and the condition they’re in.

This is the charge controller we would recommend because it allows you to harvest up to 25% more usable power from your solar power system.

A good charge controller is an invaluable piece of equipment for your solar panel setup. It’s crucial for so much more than just a boat. You also need a charge controller if you want to install solar panels on your van or RV.

It’s common knowledge that the installation of solar panels can be quite a pricey affair. It is for this reason that solar pane enthusiasts are constantly talking about the “break-even point”. This is the point at which your solar panel has saved you so much money that it has effectively paid itself off.

The average solar panel tends to reach this point within 5-7 years. However, this point can be significantly delayed and postponed if your solar panel isn’t properly maintained.

Maintenance includes the regular cleaning of your solar panel and carefully inspecting them for any signs of damage.

It is also essential that you monitor the monthly or even weekly power output of your solar power system. We recommend addressing any discrepancies in this regard as soon as possible after picking up on them.

Never hesitate to consult your solar panel provider with any queries regarding the performance of your solar panel and never hesitate to contact our experienced employees here at Shop Solar Kits for tips or guidance regarding your solar power needs.

Overall, we hope that this article has made the sailboat solar panel installation process seem a lot less intimidating and that our guidelines serve to steer you in the right direction.

By following these steps and paying close attention to the considerations we’ve covered today, you’ll definitely be able to sail through these turbulent waters with ease and have your system running to its fullest potential within no time.

Did You Find Our Blog Helpful? Then Consider Checking:

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• How to Charge Lithium-Ion Battery with Solar Panel?
• Solar Panel Positive and Negative
• Solar Panel Setup for RV
• Solar Panels for Van
• How Many Solar Panels Do I Need for My RV
• How Many Solar Panels to Run a House Off Grid
• Portable Solar Panel for Electric Car
• Solar Panels for Campers
• Why Are Solar Panels Good
• Solar Panel Maintenance
• How Many Solar Panels to Charge an Electric Car?
• Solar Panels for Mobile Home
• Solar Panel for TV and Lights
• Are Solar Panels Waterproof

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Captain Curran's sailing blog

~ a collection of sailing adventures from Alaska to Cabo

October 6, 2014

Solar panels for boats: an easy installation guide., marine solar panel installation.

• I am writing the following instructions for boat people or RV campers. 
• I describe a basic set up that provides a charge onto your 12 Volt DC battery bank.
• If you want to use this system to power your home, then you'll also need an inverter to switch the 12 Volt DC electricity to 110 Volt AC.

Ok, here's my simple DIY instructions for solar installation on a boat or an RV camper.

How to install solar panels for boats, step by step guide for installing a solar panel boat system, faq: what size panel should i get, faq: which brand of solar panel is best, faq: do i need a controller, faq: how did you mount your panel on your stern rail, faq: how do you wire up the panels/controller/battery, faq: how much will this whole solar panel project cost, solar power for boats price breakdown, okay - good luck with your marine solar panel installation ,  capt. curran, 60 comments:.

Heany - Don't hesitate, the beauty of this system is that there are no moving parts, which means maintenance is minimal.. turning photons to electrons

Good question - visit your local machine shop They should have barrels of aluminum flat panels You want 12-16 inch long, need to measure panel That's it Then drill holes and strap in on the rail Have fun!

Thanks Douglass - all the best..

Great information, thank you! Where did you purchase the white plastic rail mounts?

Hello Philip Magistro, I bought them at a boating store in Seattle - called Fisheries Supply - they may ship. But I would also check your local west marine - they are standard stern rail mounts - they fit lots of other stuff as well as solar panels. Good luck !

Excellent, glad it was helpful. I'm about to post a couple new photos of the system. Everything is still working great.

Two questions 1. Is a 30w panel large enough to trick charge two 12v batteries? 2. How large an in-line on the positive lead to the battery?

Hello - Yes, a 30watt panel is large enough to trickle charge 2 12 V batteries. That is the set up I have on my boat - it works great - even in mixed sun/cloud conditions. When you ask 'how large' an in-line on the pos. lead - I am assuming you're asking the guage. I can't give the exact guage that is suited for your set-up. But, I know that the reasonable range is between 10-14 awg. Hope that helps.. Cheers

Kevin Thanks. Great info! I was actually trying to ask type and size of fuse on the positive lead to the battery. Fingers! Cheers Bill Pierson

Thanks for a great post! I'll go with the Renogy 200 Watt kit. I know it's not as adventurous, but easier and faster. And time is money :)

Lucas, I hear ya. Time is money - best of luck with that kit. I think you've made a wise decision.... Kevin

Thanks a lot Kavin for your guidance on installing a solar panel on boat. As solar panels are the most effective and the best way of generating electricity these days so everybody wants to install a solar panel of their own. But installing a solar panel in the boat is little challenging. Thanks for sharing the step by step guidelines, it is definitely going to help the readers.

Great article. A few questions: The article explains how to hook it up to one battery. But I have a system with two house banks of two bateries each, as well as a starter battery. How do I ensure that the trickle charge gets to all give batteries? Or do you just hook it up to the starter battery? How does this system interact with my charger?

Mary, I have a similar battery bank - but the two are connected. I connect the leads of the solar panel to my house batteries. However, if they are not connected - then I would connect the leads of your solar panel to the starter battery.

Mary, I would get a MorningStar SunSaver Duo controller which can charge 2 batteries (or banks thereof) and set the 2 house banks in parallel on the controller's Batt1 and the Starter Battery on Batt2. This controller has the option to charge 90/10 or 50/50, 90/10 is best for this setup because the starting battery doesn't need much, just enough to top-it-off.

Hi Kevin, I purchased the Renogy 100w panel with controler. I like your plastic rail mounts. Where can I find those. I plan to mount this on the stern of my 73, 27' Catalina stern rail. Thanks, Chris

Chris, I got mine at a boat store in Seattle called Fishery Supplies. I just looked it up on their website. Here's the page for those rail clamps. https://www.fisheriessupply.com/sea-dog-line-removable-rail-mount-clamps-327199-1 Made by a company called Sea Dog. Good luck - Kevin

I have a 20 volt panel, single marine battery, with a controler working without problem for about 4 years. While motoring out of the marina the controler caught fire. I did not have a fuse installed as you described in your installation guide. Any idea what might have caused this? Barry

Barry Curran, That is an odd and unfortunate situation. I am not an expert on safeguarding circuits, however I can weigh in with my opinion. I do think that the installation of a circuit fuse would help prevent over-charge or over-heating happening within the circuit. I think - assuming the over-charge was happening throughout the circuit - that the fuse would have blown, thereby salvaging your controller. However, there is a chance that a diode or some other internal circuit on the controller was the weak link. In that case, I don't believe a downstream fuse would have helped save your controller. I would install a fuse and get yourself a new controller. Best of luck! Kevin Curran

Just an helpful clarification on the purpose and location of the fuse. The fuse is to protect the wire, and should be placed as close to the origination of the power source as possible which, in this case, is the positive lead near the solar panel. We're all use to hearing about locating the main fuse on a boat as close to the battery as possible; that's because that's where the power comes from. Also, the fuse should be sized based upon the length and gauge of the wire.

Thanks for that additional insight on the location of the fuse! Sorry I didn't see this comment earlier.

Thanks for sharing the helpful guide to install solar panels .

Thanks for sharing article solar installation on boats it is really informative.A Solar panel is typically a panel that absorbs solar energy and uses it as a source of energy to generate electricity. They are basically made up of solar cells or the photovoltaic cells that are arranged as a photovoltaic array making up the photovoltaic system.I know a place one of the best solar installation company provides best solar services and products that are not just economical, but also efficient with customized solutions to offer you the best from our vast range of affordable models...

Greetings, How lucky am I to have happened upon your easily understood blog. Stupid question: can I mount the solar panel flat on the deck of my Nonsuch sailboat? (I know: don’t step on it!). Will it be worthwhile? (It can’t go on the stern rail).

Yes, that can be done. If you have a bimini or any cover in your cockpit, that is probably a better location. But flat on the deck can work, you can create a border around it to prevent falling on it...

Thank you so much for your excellent blog. I am considering a solar system for my 28' Catalina sailboat. Battery question: Any problem using solar systems with AGM batteries? I have two, house and starter battery.

Hmmm, that's a good question. I have never heard of any issue with AGMs on a solar system. Any other readers here have comments?

Selecting the correct charger depends primarily on the design of your deep cycle battery, so the first thing you need to do is determine the construction type of your battery. TrollingBatteryAdvisor.com This is likely to prolong the life of each battery and save you money in the long run.

Great blog! Can I leave my solar panel attached to the battery while I'm drawing from the battery to run my trolling motor?

Anonymous, Yes, you certainly can. There is no issue with drawing from a battery that is being fed energy from a solar panel. Enjoy Captain Curran

Thanks for sharing this article here about the solar panels for boats . Your article is very informative and I will share it with my other friends as the information is really very useful. Keep sharing your excellent work.

Great to hear! Glad the post was helpful..

Thanks a lot, Captain Curran and co-Captain Jessica for a nice and informative article about "Marine solar panel installation". This article will surely help the sailor in the Sea. And using a solar panel in the mid-sea is a very nice idea as an alternative source of power. Best wishes from SolarPandit

Thank you very much, Captain Curran and co-Captain Jessica, for a very interesting and insightful post on "Marine solar panel installation." This article will undoubtedly assist the sailor at sea. Using a solar panel and  in the middle of the sea as an alternate source of electricity is also a great idea.

Hello all, Great to see the article has been helpful for those putting panels on their boat. Don't hesitate to reach out with any questions. I changed the notification, so I should be pinged when someone asks a question. Fair winds!

The Renogy 30 Watt Solar Panel is an excellent choice for light energy users, while the 100 Watt Solar Panel is preferred for moderate energy users. And remember to use a suitable quality controller like the Morningstar SunSaver-10 to control the panel's charge and prevent over-charging the battery.

Their step-by-step guide for installing solar panels on boats is incredibly helpful, and I appreciate the personal touch of sharing their own experiences and the success they've had with their solar panel system. The detailed explanations, recommended products, and estimated costs make it easy for someone like me to envision completing this project over a weekend. I'm definitely inspired to take on this DIY installation and enjoy the freedom of generating my own energy while sailing.

I can’t really help but admire your article your topic is so adorable and nice.

Forbidden love in a mesmerizing supernatural universe. Anime like Devils Line

Captain Curran's guide to installing solar panels on boats is a real lifesaver! After following his easy-to-understand steps, I completed my own installation over a weekend, and now my boat's batteries are always topped off during my fishing trips in the Chesapeake Bay. No more worries about a dead battery spoiling the fun!

Hello Captain, Great article, thank you. Our vessel has (6) 6 volt golf cart batteries, a 2000 Watt inverter, plus a generator. I want to limit the generator recharge time by installing a 100 or 200 watt kit that you recommend. My question is can I just connect the pos. and neg. marine grade wires from the controller directly to my battery bank pos. and neg. Thanks, John

This article on installing solar panels for boats brought back memories of my own sailing adventures along the coast of California. I remember the frustration of being stranded due to a dead battery and the relief that came with finding a solution. Capt. Curran's step-by-step guide is not only practical but also reflects his passion for sustainable energy solutions, making it a valuable resource for fellow sailors.

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9 Best Solar Panels for Sailboats

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Solar panels have become game changers when it comes to supplying power while off the grid. Marine solar panels can charge anything from batteries to computers to bigger electronic appliances. What are the best solar panels for sailboats? 

The 9 best solar panels for sailboats are: 

• Renogy Flexible Solar Panel
• Newpowa Solar Panel
• SunPower Flexible Sol ar Panel
• Eco-Worthy Off-Grid Solar Panel
• Rich Solar Polycrystalline
• Topsolar Flexible Solar Panel
• HQST Monocrystalline Solar Panel
• WindyNation Solar Panel Complete Off-Grid
• DOKIO Solar Panel Kit

This article will explore everything you need to know about the best marine solar panels. 

Table of Contents

Solar Panels on Sailboats: An Overview

Before exploring the best solar panels, it is helpful to consider how solar panels on sailboats work and how many you need. Solar panels sit on different parts of a sailboat’s surface and absorb the sun’s rays, converting them into energy. This energy is used to power chargers, fridges, cooking stoves, and other electronics you need for self-sufficient sailing. 

Worth noting is that today we will only discuss solar panels and not the batteries, which of course is an essential part of a complete system; we will also not discuss charges or charge controllers.

The products in this post will get you started in the right direction, but if you’re looking for a high-output system, then I suggest you contact someone that can help you calculate your energy requirements.

How Many Solar Panels Do I Need for My Sailboat?

You will need between 2-8 solar panels for your sailboat. The exact amount depends on your sailboat’s space and how many electronics you need to power. Most solar panels can absorb between 100-300 watts per hour. On average, you will need approximately 1500 watts of power each day. 

If your solar panels absorb 1500 watts daily, here’s what they can power on your sailboat: 

• A laptop charger
• A microwave 
• A coffee maker 
• An induction cooker 

If you want to power more heavy-duty electronics like a washing machine or a television, look for solar panels that absorb 400 watts. For heavy-duty electronics, try installing 5-8 solar panels. 

Flexible vs. Rigid Solar Panels

The three main types of solar panels are rigid panels, flexible panels, and semi-flexible panels.

Rigid panels are surrounded by aluminum and made with sturdy tempered glass. They are resilient against various weather conditions but require flat space to install. 

Semi-flexible panels can be slightly bent to fit the shape of the installation surface. However, they can’t absorb a lot of power. 

One very common type of solar panel used on boats is the flexible panel . Flexible panels are thin and lightweight, and, as their name suggests, they can be added to a wide variety of surfaces. 

Here are the pros of flexible panels: 

• They are thin and light. Flexible panels are approximately one-eighth the weight and size of rigid and semi-flexible panels. This allows you to add them to various sailboat sizes and surfaces. It also reduces the load on your sailboat. 
• They are easy to install. Flexible panels are easy to work with and can be self-installed by following the instructions that come with the panels. Meanwhile, rigid and semi-flexible panels may require expert installations. 
• They’re sturdy. Despite being light, flexible panels can bear a lot of pressure – you can easily walk over them. 

However, there are also some drawbacks to using flexible solar panels: 

• May fly away . As flexible panels are fragile, they can easily be dislodged and fly away, especially in strong winds. 
• Vulnerable to scratches . While flexible panels can bear much weight, they may get scratched more easily. Over time this may affect their functionality. 
• Not easy to reposition. Flexible panels are generally adhered to the surface of a sailboat using a specially prepared adhesive. Because of this, it is challenging to reposition the solar panels when there is a change of season.
• Less efficient. Flexible solar panels don’t convert energy to electricity or rigid panels. It may be harder to power heavy-duty appliances from a flexible solar panel. 

How Many Panels Can I Fit on a Sailboat (Catamaran and Monohull)?

The amount of panels you can fit on your sailboat depends on the size of the panels and the surface space you have available. 

You can fit at least two 400W panels on a Monohull and at least four on a Catamaran around 35ft in length. You will be able to fit 4-8 more solar panels if you add a solar panel bracket at the stern. 

Renogy Flexible Solar Panel 100W

Renogy is a popular solar panel producer that designs high-quality solar panels. The Renogy Flexible Solar Panel is specially designed for marine vehicles, including sailboats. 

Here are the best features of this solar panel: 

• Flexibility . These solar panels are fragile, making them flexible and easy to mount on served surfaces. 
• Easy to install. These are made with high-quality Monocrystalline, allowing them to be easily bent and easy to install. 
• Lightweight. One solar panel weighs only 4 pounds, ensuring that no extra pressure or weight is displaced on your boat. 
• Durability . User reviews have noted that these panels are highly durable and can last you a few years. 
• Users have noted that these panels do not have the best outputs. They also can’t be stacked, which impacts their accessibility. To ensure that these panels can be connected, you may purchase extra extension cords. 

Newpowa Rigid 160W Solar Panel

The Newpowa Right Solar Panel is a new design with a maximum power of 160W. It is weather-resistant and can be used on various surfaces and vehicles. 

Here are the pros of the Newpowa Solar Panel: 

• Weatherproof . The design features of this solar panel ensure that it survives under a range of different weather conditions. It has a heavy-duty frame preventing it from strong wind and waves. Its mainframe has a further layer of protection for the Junction box. 
• Long warranty . Newpowa offers a 25-year transferrable output power warranty. 
• Easy to install . These solar panels are made with mono cells and bypass diodes. Consequently, the solar panels can be immediately unpacked and are ready to install. 
• High wattage. As these solar panels have 160 Watts of power, you need less of them to power all the devices on your boat. 
• If you are planning on buying the Newpowa Solar Panel, you should note that they only make rigid panels. As a result, you may find it to be difficult to install them on curved spaces.

SunPower 110W Flexible Solar Panel

SunPower’s Flexible Solar Panels are made with high-quality materials ensuring durability. They are especially ideal for sailboats as their warranty also covers saltwater damage. 

Here are the standout features of the SunPower 110W Flexible Solar Panel: 

• Flexibility . This solar panel can be bent up to 30 degrees, making it easy to install on various surfaces. 
• Easily portable. These solar panels are incredibly lightweight (4.4 pounds or 2 kilograms) and can be easily uninstalled and transported. 
• Extended warranty . SunPower offers a five-year warranty on power and a two-year warranty on the product. The warranty includes damage caused by saltwater which many other solar panel warranties do not. 
• Some users have noted that the output quality of these solar panels deteriorates over time. However, you can use the extended warranty to address any quality deterioration. 

ECO-WORTHY Rigid 25W Off-Grid Solar Panel

This is a rigid, 25-watt solar panel that is waterproof, making it ideal for your boat. It is highly durable and has inbuilt indicators that highlight the battery’s status. Its low output makes it only suitable for charging phones or smaller electronics.

Here are some notable features of the Eco-Worthy Solar Panel: 

• Ease of use. This solar panel is easy to install and requires no maintenance. 
• Warranty. Eco-Worthy offers one year of warranty on all of its products and free maintenance if needed. 
• USB control. This solar panel is attached to a USB control panel, preventing it from overcharging and getting damaged. 
• Waterproof. All solar panel parts are entirely waterproof and can handle exposure to both saltwater and freshwater. 

Some of the drawbacks to this solar panel include: 

• Low watt absorption. Unlike many of the other solar panels on this list, this one can only absorb up to 25 watts of power at a time. So, it can only power smaller devices like batteries. 
• Instruction manual. Some users have noted that the instructions to set up the Eco-worth solar panel are confusing for beginners. If you have never installed solar panels before, it’s best to call in an expert to help. 

RICH SOLAR 100W Rigid 12V Polycrystalline

This 100W rigid solar panel is designed to absorb energy even in low light conditions. It is easy to install and ideal for marine environments. 

Here’s why you should consider buying Rich Solar Panels: 

• Works well in low light. This solar panel has been tested in various low light conditions, including cloudiness and during sunrise and sunset. It is certified to be able to harvest energy in low light conditions. 
• Extended warranty. Rich Solar Panels offers a 25-year warranty on limited power output and a five-year warranty on quality. 
• Water and weatherproof . The Rich Solar panels have used selective design elements to ensure they are water-resistant. They have high transparency and are made with tempered glass to withstand high winds and water pressure. 
• Cost-effective . These are significantly cost-effective, making it easy to equip your sailboat fully. 
• While solar panels can easily resist strong winds and water, they can be vulnerable to hail. Hail storms can cause dents on the solar panels, which can eventually cause damage. 

Topsolar Flexible 100W Solar Panel

Topsolar provides premium flexible solar panels that are easy to move and install. They are ideal for installing on water vessels like sailboats with waterproof materials. 

Here are some of the pros of choosing the Topsolar Flexible Solar Panel: 

• Flexibility . The arc radius of this solar panel is 16 inches (40 centimeters) and can be bent to fit several curved surfaces allowing your solar panel to harvest the most sun. 
• Efficiency . These solar panels are made with ETFE (ethylene tetrafluoroethylene) materials. They are extremely energy efficient and can rapidly convert energy. 
• Some users have noted that these solar panels don’t have as long a life as other panels. In addition, some panels may only be able to absorb up to 75 watts of power at a time. 

HQST Rigid 100w Monocrystalline Solar Panel

This is a 100-watt solar panel that has been specially designed to perform well in low light. It is made with high-quality materials and is ideal for sailing boats as it is durable even in unfavorable weather conditions. 

Here are the pros of installing the HQST Solar Panel: 

• Durability . These solar panels are designed to withstand strong winds and snowfall. They’re made with tempered glass and aluminum and are resistant to corrosion, ensuring longevity. 
• Testing and warranty. Each solar panel is quality tested before it is distributed. It also comes with a three-year warranty. 
• Easy to install . While these are rigid solar panels, they have pre-drilled holes, making them easier to install. 

WindyNation 100W Solar Panel Complete Off-Grid

As its name suggests, this solar panel is designed for off-the-grid living and is helpful if you need to access power when you’re in the middle of the sea. 

Here is why you should consider the WindyNation Solar Panel: 

• Includes a charge controller. This controller lets you quickly see the amount of power the solar panel has absorbed. 
• High power. Several positive user reviews have indicated that this solar panel is highly efficient in absorbing and converting power. 
• This solar panel is more expensive than many others on the market.

DOKIO 300W 18V Portable Solar Panel Kit

If you are looking for a heavy-duty solar panel, the Dokio Solar Panel Kit is excellent. It can absorb a lot of energy and power a wide range of appliances on your sailboat. 

Here’s why you should consider this solar panel: 

• Versatile and flexible. While this is a rigid solar panel, it can be folded, making it easy to transport and install. 
• High efficiency. This solar panel is highly efficient at converting energy into power. As it absorbs up to 300 watts, you can install just two of these panels to get significant energy. 
• Some users have noted that this solar panel does not work well in low-light conditions. You may want to have a backup solar panel for days when it’s rainy and windy. 

Here are Some of My Favorite Catamaran Cruising Resources

Thank you for reading this article. I hope you found it helpful as you hopefully start your sailing adventures. Here are some resources that I use as a sailor that I hope you’ll also find helpful. These are affiliate links, so if you do decide to use any of them, I’ll earn a commission. But in all honesty, these are the exact things that I use and recommend to everyone, even my own family. Sailboats: If you’re looking for the best boat to suit your needs, I would recommend a catamaran. If you’re interested, I can show you the differences between catamarans and other types of sailboats .

Books:  For getting started, I really like  Cruising catamarans made easy . It is actually a textbook from the American sailing association; it is used to get a cruising catamaran certification. There are some other great books, and I have compiled a list of books about cruising catamarans that you will find useful.

Communication:  Being out on adventures, whether it be sailing or climbing mountains, good communications are essential to being safe. I recommend two things Google fi (incredibly simple cellular data all over the world) and Garmin inreach mini (for text and voice in remote areas without cell coverage)

Sailing courses: Online sailing courses are great for beginners starting out their sailing career; it’s an efficient way of learning the basics of navigation, throttle controls, and maritime safety. I suggest starting with two free courses from NauticEd .

To see all my most up-to-date recommendations,  check out this resource  that I made for you!

Owner of CatamaranFreedom.com. A minimalist that has lived in a caravan in Sweden, 35ft Monohull in the Bahamas, and right now in his self-built Van. He just started the next adventure, to circumnavigate the world on a Catamaran!

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Guide to Equipping Your Boat with Solar Power: A Complete System Breakdown

Posted by Tina Kassaeian on July 7, 2023

As boaters increasingly prioritize environmentally friendly and sustainable power solutions, harnessing solar power has gained popularity. In this comprehensive guide, we will explore the essential components necessary to create a reliable and efficient solar power system for your boat. From solar panels and batteries to inverters and solar charge controllers , we will provide an in-depth explanation of each component. 

By the end of this guide, you'll have a clear understanding of how to equip your boat with a robust solar power system.

Understanding the Components of a Boat Solar Power System

Solar panels: the backbone of your system.

Solar panels are crucial components of a boat solar power system as they convert sunlight into usable electricity to power your boat's electrical devices. There are various types of solar panels available, including monocrystalline, polycrystalline, and thin-film panels.

Efficiency: Monocrystalline solar panels are known for their high energy conversion efficiency. This means they can generate more electricity from the same amount of sunlight, making them a suitable choice for boats with limited space for solar panel installation.

Factors to Consider

• Panel Sizing: Assessing your energy needs and available space will help determine the appropriate size and number of panels required for your boat.
• Placement: Solar panels should be placed in an area on your boat that receives maximum sunlight exposure throughout the day, typically on the deck or roof. Avoid shading from obstacles like antennas or sails.
• Tilt Angles: Adjusting the tilt angle of the panels seasonally can optimize their performance. Tilting the panels toward the sun's angle during winter and adjusting them to a flatter angle during summer maximizes energy generation.

Installation Considerations

Mounting: Securely mounting the panels using appropriate hardware and brackets ensures they remain in place even during rough waters.

Wiring: Properly routing and protecting the wiring from the panels to the battery bank is crucial for safety and efficiency.

Maintenance: Regularly inspecting and cleaning the panels to remove dirt, debris, and salt build-up ensures optimal performance.

By selecting high-quality solar panels and considering factors like panel sizing, placement, tilt angles, and installation best practices, you can maximize the efficiency and output of your boat's solar power system.

Batteries: Storing Energy for Extended Usage

Batteries are essential components of a boat solar power system as they store the excess energy generated by the solar panels for later use, ensuring a continuous power supply even when sunlight is limited. Here are key points to consider when selecting and maintaining batteries for your system:

Importance of Selecting the Right Battery

• Capacity: The battery capacity determines the amount of energy it can store. Assess your boat's energy requirements to choose a battery with sufficient capacity to meet your needs.
• Lifespan: Consider the battery's lifespan, typically measured in cycles (number of charge and discharge cycles it can endure), and select a battery with a longer lifespan for optimal value and longevity.
• Maintenance Requirements: Some batteries require regular maintenance, such as checking water levels and specific gravity, while others are maintenance-free. Evaluate the maintenance needs and choose a battery that aligns with your preferences and abilities.

Battery Technologies

Li-ion batteries have gained popularity in marine applications due to their high energy density, lightweight design, and longer lifespan compared to traditional lead-acid batteries. They offer efficient energy storage, faster charging times, and are generally maintenance-free.

Proper Sizing and Maintenance

• Sizing: Properly sizing your battery bank involves calculating the total energy consumption and determining the number and capacity of batteries needed to meet your power requirements. Consider factors like daily energy usage, charging time, and days of autonomy (the number of days the batteries can sustain the boat without solar input).
• Maintenance: Regular battery maintenance includes monitoring the state of charge, avoiding over-discharging or overcharging, and periodic checks of connections and battery health. Adhering to the manufacturer's guidelines ensures optimal performance and extends battery life.

By selecting the right battery technology, such as lithium-ion batteries, and considering factors like capacity, lifespan, and maintenance requirements, you can ensure reliable energy storage for your boat's solar power system. Proper sizing and diligent maintenance practices will maximize the performance and lifespan of your battery bank, providing sustained power for your boating adventures.

Inverters: Converting DC Power to AC Power

Inverters are essential components of a boat solar power system as they convert the direct current (DC) power generated by solar panels and stored in batteries into alternating current (AC) power, which is used by various electrical devices onboard. Here's what you need to know about inverters:

• Functionality: Inverters take the DC power from the batteries and transform it into AC power, mimicking the power supplied by the utility grid. This enables you to power AC appliances, electronics, and devices on your boat.
• Features: Inverters can have various features, such as pure sine wave output, multiple AC outlets, built-in protection mechanisms (like overload and short-circuit protection), and remote monitoring capabilities.
• Sizing: It's crucial to properly size your inverter to meet your power requirements. Consider the wattage or power ratings of the appliances and devices you plan to power simultaneously to determine the appropriate inverter size.

Charge Controllers: Regulating the Flow of Power

Charge controllers are vital for regulating and protecting your batteries from overcharging, ensuring their longevity and optimal performance. Here's what you should know about charge controllers:

• Functions: Charge controllers monitor the state of charge of your batteries, regulate the flow of power from the solar panels to the batteries, and prevent overcharging. They may also provide additional features like load control and battery temperature monitoring.
• Types: There are primarily two types of charge controllers: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking). MPPT charge controllers are more efficient and can extract more power from the solar panels, particularly in situations with lower solar panel voltage than the battery bank voltage.

Wiring and Connectors: Ensuring a Reliable Connection

Proper wiring and connectors are essential for effectively transferring power between the solar panels, batteries, and other components of your boat's solar power system. Here are key considerations:

• Types of Wiring: Marine-grade and UV-resistant wiring should be used to withstand the harsh marine environment. Tinned copper wire is commonly used due to its corrosion resistance and superior conductivity.
• Wiring Protection: Adequate protection, such as conduit or wire looms, should be employed to safeguard the wiring from physical damage, UV exposure, and moisture.
• Connectors: High-quality connectors designed for marine use, such as waterproof and corrosion-resistant connectors, ensure reliable electrical connections and minimize power losses.

Selecting the Best Components for Your Boat Solar Power System

Volts energies 100ah battery: power and reliability.

The Volts Energies 100AH battery stands out as an excellent choice for powering your boat. With its robust construction, long lifespan, and high energy density, this battery offers exceptional performance and reliability. 

Its advanced technology ensures efficient energy storage and discharge, allowing you to meet the power demands of your boat while maintaining optimal system performance.

Volts Energies Mono Solar Panels: Efficiency and Durability

When it comes to solar panels for your boat, Volts Energies Mono Solar Panels excel in both efficiency and durability. These panels utilize monocrystalline technology, which maximizes their energy conversion efficiency, ensuring you can generate more power with limited space. 

Additionally, they are designed to withstand harsh marine environments, featuring corrosion-resistant materials and reinforced frames to ensure long-lasting performance.

Victron Inverter: Reliable Power Conversion

Choosing a reliable inverter is crucial for converting the DC power stored in your batteries into AC power for your boat's electrical devices. Victron inverters are renowned for their high-quality construction, advanced power electronics, and robust performance. 

With features such as pure sine wave output, high surge power capacity, and excellent load handling capabilities, Victron inverters provide stable and clean power for sensitive electronics onboard your boat.

Victron Charge Controller: Optimal Battery Management

To regulate the flow of power and protect your battery bank, a high-quality charge controller is essential. Victron charge controllers offer advanced MPPT (Maximum Power Point Tracking) technology, ensuring optimal energy harvest from your solar panels. 

They also provide comprehensive battery management features, such as temperature compensation and intelligent charging algorithms, to prolong the lifespan of your batteries and maximize their performance.

Building a robust solar power system for your boat is a wise investment, providing reliable power while minimizing your environmental impact. Incorporating the Volts Energies 100AH battery, Volts Energies Mono Solar Panels, and Victron inverter ensures a highly efficient and durable setup for your marine adventures. 

With careful consideration of each component and proper installation, you can enjoy a sustainable and independent power source while cruising on your boat. Contact Volts Energies in Canada to explore the best solar and renewable energy equipment options and embark on your journey to greener boating today.

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Frequently Asked Questions

At Sun Powered Yachts we understand you will likely have some great questions about marine flexible solar panels, the SunPower difference and how you can install a SunPower/Maxeon solar system on your yacht. 

We hope that you will have found a lot of great info so far and can also use the FAQ page as a good resource.  Scroll down, or click on the search icon and type what you're looking for, to find out more. 

(Note: see if we're available on chat to answer your question right away and also check back as we're always adding more FAQs to this page.)

• Where can we find you? Sun Powered Yachts is based on the Big Island of Hawaii and we recently returned to landlife after 15 months living aboard our sailboat, a Dufour 382. We sailed from Corsica to Cancun, crossing the Atlantic with the ARC 2021 sailing rally and exploring the Caribbean and Central America during 2022. We then sailed to Key West and on to the Bahamas. Currently we are back in Hawaii. We're happy to answer any questions on the phone & email about sailing and going solar aboard your yacht. In person we will next be attending the Palm Beach International Boatshow (March 21-24, 2024).
• Can I charge my 24V or 48V battery bank with solar? Yes. Most solar MPPT charge controllers move power from higher voltage solar panel(s) to a lower voltage battery bank. These are called 'buck' controllers and the full range of Victron Energy SmartSolar MPPT charge controllers are 'buck'. So you need to have a solar panel array voltage that is greater than your battery voltage. The Victron MPPT controllers will auto detect what battery voltage they are connected to ie. 12V, 24V or 48V In contrast, if you didn't have the 'roof space' to have a large solar panel array then you may have a lower voltage panel that would need a 'boost' controller. This will take lower voltage solar panel(s) and boost it up to charge a higher voltage battery bank. A good example is the Genasun GVB-8 (boost) controller. If charging a 36V-52V nominal battery bank, the GVB-8 (Boost) controller is ideal with any SunPower flexible solar panel. Please check the spec sheets for detailed parameters or visit Genasun online
• My electric motor has a high voltage battery bank, can I charge with solar? Yes. We are confident that we can help you find a solution to charge your battery bank with SunPower solar panels. Some brands of electric motors require higher voltage battery banks eg 96V or 108V and your typical MPPT controller will only go up to 48V. We have worked on a few projects now with Elco and Torqeedo to find a solar charging solution. Please email us and we can help you with your project and in our shop we have a high voltage charge controller manufactured by AERL in Australia. An Elco EP-50 electric outboard requires a 96V (nominal) battery bank which requires a specific high voltage MPPT charge controller.
• What is Light Induced Degradation (LID)? This is a loss of performance (1-3%) of brand new panels when first exposed to sunlight. Fortunately SunPower® flexible solar panels are NOT effected by LID and as such retain their high levels of performance (efficiency). The simple answer why is that the silicon used in the SunPower® cells is of a different type. SunPower uses n-type silicon and only p-type silicon found in conventional panels is effected by LID as it is boron-doped and suffers from the boron-oxygen effect when first exposed to sunlight. Yet another reason why SunPower is better.
• What is a conventional solar cell/panel? A conventional solar cell is easily recognised by the thin metal lines that are on the front of the solar cell (cells on left of image) These thin metal lines are usually a cheap, aluminum paste which reflects the sunlight, covers the active solar surface of the cell & due to being porous is susceptable to moisture corrosion. This all contributes to the lower efficiency of the conventional cell which is typically around 15% SunPower cells by contrast are easily recognised by an absence of metal lines on the front and have a solid dark appearance (cells on right of image) There is nothing blocking the active surface as the contacts are allprotected on the back of the cell.
• Should I keep my panels clean? The more sunlight that hits a panel, the more power it generates. Typically panels are self cleaning with normal rainfall. However, on your yacht, they are more prone to bird droppings and a build-up of general dust and dirt that does not wash off with just rain. Therefore, we recommend periodic cleaning of your E-Flex panels with non heated water, mild soap and a soft sponge to wipe the surface clean in a circular motion.
• Can I recycle my old solar panels? A. Absolutely. As many fixed solar panels are now coming to the end of their lifecycle (20-25 years+) we are starting to enter a time where more and more solar panels will need recycling. This is the same for the newer flexible solar panels and it's important to recycle and keep solar panels out of landfill. SunPower has been committed to being a responsible producer and provides appropriate reuse and recycling options for their products. SunPower is a Founding Member and on the Board of Directors of PV Cycle for more info check out www.pvcycle.org contact your local SunPower dealer or email us and we'll help you recycle your old solar panels. ​​
• I have a Watt&Sea, can I connect solar panels to my controller? After chatting with the very helpful tech support at Watt&Sea we have the following info: Since 2014 the Watt & Sea hydrogenerator charge controllers can also receive solar input. The minimum PV voltage input is 7.5V, maximum PV voltage input is 50V & maximum amps input is 14A. So as long as you stay within these parameters you are OK. It is worth noting that the controller will only charge your batteries from one source at a time (hydro OR solar) NOT both at the same time. So when your hydrogenerator is not in the water/spinning to create hyrdro then it will recognize the solar input. An alternative option may be to install your own MPPT charge controller just for your solar panels. The Watt&Sea controller also has the ability to charge two battery banks (ie. your house bank and engine start battery) as long as they are the same voltage (both 12V or both 24V)
• How can I calculate Amps? Use the magic triangle below to calculate Amps, Watts or Volts. Watts = Volts x Amps (eg. 100W = 17.1V x 5.9A) Amps = Watts ÷ Volts (eg. 5.9A = 100W ÷ 17.1V) Volts = Watts ÷ Amps (eg. 17.1V = 100W ÷ 5.9A)
• What is Affirm and Sezzle? Both Affirm and Sezzle are options at checkout that allow you to spread the cost of your purchase over a number of months with zero interest if it's paid off in full. We can also email you an invoice and then just select to pay with either Affirm or Sezzle. You then have to set up an account with them and you are on your way to enjoying clean & quiet solar power.
• Can I mix solar panels of a different wattage, eg. 110W and 170W? Yes you can, BUT it is not ideal and certainly needs more attention and thought before setting up. It is certainly better & recommended to wire together panels from the same manufacturer and the same panel wattage (or wire individual MPPT charge controllers) If you do plan on wiring dissimilar panels, you should know that: a) For series connection – the same current rating of the panels is more important b) For parallel connection – the same voltage rating of the panels is more important So as an example if you only had space for 1x110W panel on the dodger and 1x170W panel on the bimini then first I would recommend seperate charge controllers for each panel. If however you did want to go ahead and wire them together then you should look at the spec sheets and see if the current rating or voltage rating are more similar (closer together in value). The SunPower 110W is rated at 18.8V and 5.9A The SunPower 170W is rated at 29.4V and 5.84A As the current rating is very similar (0.06A difference) then in this example we would wire 1x110W & 1x170W together in series. However it's worth noting that performance will only be as good as the weakest link. So in this example both panels will only produce 5.84A - the current rating of the 170W panel, which is the lower of the two.
• What size MPPT charge controller do I need? Have a look at our install page where you will find the range of Victron Energy SmartSolar MPPT charge controllers. Each has a max PV for the input, but it's important to look at some other parameters. 75|10 - $109.80 - PV Input: 12V - Up to 145W 24V - Up to 290W 36V/48V - N/A Feel free to email us and we can help size the correct controller for the number of solar panels and battery bank voltage you have aboard.
• Who is the ABYC? The ABYC is the American Boat and Yacht Council, a voluntary standards creating body for the marine industry responsible for Standards and Recommended Practices. It's a great resource and we are proud to be a member, click here for more info on membership. Visit their website to learn more www.abycinc.org
• How much power will I get from my panel? There are more complicated ways to estimate how much power you are likely to get from your panel and performance will vary depending on weather conditions, shading etc. But to keep it simple you can follow this trick to get a potential daily yield in terms of amp hours (for a 12V system): For SunPower panels: divide the panel wattage by 3 For non-SunPower mono-panels: divide the panel wattage by 4 For non-SunPower multi-panels: divide the panel wattage by 5 So for the SunPower E-flex series of panels in a day and on a 12V system you could have a potential daily yield of: 50W divide by 3 = 16-17amp hours 110W divide by 3 = 36-37 amp hours 170W divide by 3 = 56-57 amp hours
• Do you sell fixed frame solar panels? Yes. Since 2019 we have offered SunPower DC solar panels for sale to individual end customers to use on their boat or RV. Since 2023 we now only offer Maxeon DC solar panels. Visit our Fixed Frame page for more info. Currently we are offering the 415W-R & 470W panels.

Have a question we haven't answered?  See if we're available in chat (green round icon at bottom right) and we'll answer straight away or fill out the form below and we'll get right back to you. 

Thanks for your question, we'll get back to you via email shortly.

INSTALLING SOLAR PANELS ON A BOAT

Solar panel technology has improved tremendously in the past few years. The panels are highly efficient, flexible, walkable and comes with very low weight. They can be attached to the deck or canvas  with fasteners such as Tenax/Loxx, using velcro or glue. Some panels are suitable for boom/mast assembly as well. The latest technology allows also putting panels onto sails .

Oceanvolt uses solar panels from Sunbeam . The panels have proven to be reliable and efficient with good value for money.

The panels can charge either 12/24 VDC house battery or the 48 VDC propulsion battery bank. Charging the house battery bank is no different than in normal installation: a charge controller must be added compatible with the panel power. Charging a 48VDC  lithium ion propulsion battery bank   is however a little more challenging.

Lithium Ion batteries require careful balancing to remain fully operational. The balancing is a slow process and thus can be completed only with shore power charger or with solar power: a generator or regeneration under sails can never  reach the 100% level as the process is designed to cut off the charge at 80-90%. In applications where shore power is not available some solar power is a requirement – Oceanvolt recommends minimum 200 W of solar panels in this case.

Using solar panels with Oceanvolt propulsion system requires either Victron MPPT series charge controller or Genasun Li-Ion Boost controller. The former is used where the amount of panel voltage is 60-150 VDC/70 amps, the latter if the panel voltage is less than 60 VDC (max 8 amp). The advantage of the Victron MPPT is that it does not require an external balancing relay (the Genasun requires this)  & it is fully compatible with the Victron GX which allows remote monitoring of the solar yield.

Panels on the same side of the sun should be connected into the same group if connected in series. Otherwise shading will have significant effect on the power. However, two panels on the opposite sides of the boat can be connected in parallel: one is likely to be on the sun when the other is not.

There is no upper limit for the amount of panels. The number of MPPTs depend on the amount of panels. Oceanvolt has done boats with up to 5 kW (50x 100 W) panels.

SOLAR MOTORING

It is possible to do solar motoring with the Oceanvolt system. The system shows the current yield from the panels and the motor speed can easily be adjusted to match the solar power to get independency. Typically 1 kW of solar gets about 3 knots for a boat suitable for Oceanvolt motors.

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Flexible Solar Panel on Bimini - Backing?

• Thread starter Monterey385
• Start date Apr 3, 2021
• Forums for All Owners
• Ask All Sailors

Monterey385

I am planning to install two Renogy 175 watt flexible solar panels on my bimini this summer. After numerous detailed conversations with several local canvas professionals and marine electronic professionals, the consensus is that I should keep it simple for the first few months if not the first entire season. By simple, they are suggesting that I stick with bungee cords to make it simple to remove the panels for various reasons (high wind events, extended periods at dock, etc.). My question, what are the group's recommendations to mitigate chafe under the panels? I have seen references to a variety of fabrics and liners but am uncertain right now about the best options ... thoughts?  

Sailrite has a decent how - to video on attaching a flexible solar panel. Backing matl. for chafe ,matl. list and details. I am planning on the install myself in the near future.  

Joe23455 said: Sailrite has a decent how - to video on attaching a flexible solar panel. Backing matl. for chafe ,matl. list and details. I am planning on the install myself in the near future. Click to expand

Installing Semi-Flexible Solar Panels - Marine How To

dlochner, thank you for posting the Solbian how to. I saw that a while back and could not locate where I had seen it ! I like the velco details. Sailrite does not use that detail and I am a little leary of snaps only. Adhesive I think.. would cause heat buildup and ruin the bimini surface forever if the adhesive was also used on that. Just my thoughts in researching the install. Doing the same homework.... The bungee would work for a while but not UV tolerant, might last a season ?.  

dlochner said: Here's another option. Installing Semi-Flexible Solar Panels - Marine How To Panel Layout In this article we used a Solbian panel that is no longer in production. Solbian solar panels are a unique product that fill a great niche for the marine market. They are really the absolute top tier semi-flexible panel marinehowto.com Click to expand

Joe23455 said: The bungee would work for a while but not UV tolerant, might last a season ?. Click to expand

McMaster-Carr

We used 3M dual lock on our panels the last couple of years. My wife sewed the non stick dual lock to the bimini fabric and we used the self adhesive type on the panels. It worked well. We're having all new canvas installed on the boat this year, and our canvas guy is using zippers for the new canvas (like was pictured a few posts above).  

THECUSCUS said: [URL="https://forums.sailboatowners.com/media/northernstarsolar1.26195/"] [/URL] Have had a Solbian panel held on to my bimini with zippers for the past 4 years with no problems. It doesn't go over any of the framework. Zippers on two long sides only, allows air to flow in on the short sides. Super easy to install and remove when needed. Have never felt excessive heat underneath. Click to expand

DArcy said: How is the zipper attached to the panel? Click to expand

I attach1/4" thick clear twin-wall polycarbonate panels to the back of the flexible panels. You can get these at Home Depot. These are used for green house windows. They are extremely light and are almost invisible under the panel. I attached the panel to the polycarbonate using 1" bits of 3M VHB tape. The polycarbonate is flexible enough to follow the curve of the bimini but stiff enough to protect the flexible panel from flexing too much. This also insulates the bimini fabric from the hot panel. With the polycarbonate you can also run the panels across the bimini bows. I sewed little sunbrella loops to the bimini and then simply tie the panel to the loops with thin dyneema cord. I've had no problem with the panels lifting in the wind. They just lie there even in 40knot winds. Also no visible chafe in three years on the sunbrella - which makes sense as the polycarbonate is very smooth (I did wrap chafe tape along the edges). If I need to take the bimini off for a storm, I just cut the cord, store the panels, and then retie with new cord after the storm (BTW, install some form of wire connector so you can put your panels below during a storm). Be extremely careful handing the flexible panels. Don't let them "flop" around when installing. Bending one just a little too much will break a solder joint inside rendering it useless. Also, be sure you have a good warranty for your panels (Renogy does well) and that you have an easy way to take a panel off to send back for a warranty replacement. About half of these panels fail in two years - especially in Florida and southern areas.  

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Owning a boat can be expensive; you have to pay an upfront cost to purchase it, and you'll also have to spend money on maintenance and fuel charges. Solar panels may be the answer if you're looking for a reliable, cost-effective way to power your boat.

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How do solar panels work on boats?

Solar energy systems on boats work similarly to other portable , off-grid systems. There are four important components to a marine solar panel system:

Solar panels

Charge controller

Most marine solar panel systems require charge controllers to prevent the batteries from receiving more voltage than they can handle. Without charge controllers, you risk overcharging and damaging your battery.

Depending on your boat's electrical setup and the appliances you need to power, you may also need an inverter to convert direct current (DC) electricity into alternating current (AC) electricity. Some boat electronics use DC and don't need an inverter. However, if you use everyday household appliances on your boat (i.e., TVs, microwaves, or hairdryers), they likely run on AC electricity, and you'll need an inverter.

You can buy all of these components separately, but you can find solar panel kits that include some or all of the necessary parts. Some marine solar panel kits include the wires, cables, and mounting equipment required to get your boat's solar panel system up and running.

Best solar panel kits for boats

Below are a few products tailored to off-grid marine solar power systems.

Boat solar panel options

If your solar panel kit does not include an inverter or charge controller, you must buy those components separately. Battery storage products occasionally have built-in inverters and/or charge controllers.

Should you install solar panels on your boat?

There are numerous benefits to powering your boat with solar energy. One of the most attractive benefits of marine solar power systems is the monetary savings. You'll need to invest money upfront to purchase solar equipment; however, once it's up and running, you'll generate free electricity for your boat. Alternatives to electrifying your boat, like gasoline-powered generators, require purchasing fuel on an ongoing basis. Switching to solar power can reduce these purchases while protecting you against rising fuel costs.

Another benefit of marine solar panel systems is the quietness of operation. Running a generator can be a noisy disturbance for those going out on the open water to experience nature. Powering your boat with solar allows you to enjoy peace and quiet without losing power.

Furthermore, you can also safely generate electricity and charge your battery with solar power while you're away from your boat. This isn't feasible with generators - running a generator requires manual operation and monitoring. With solar panels, you can produce usable electricity during the day and then use it for weekend boating adventures.

However, there can be obstacles to installing solar on a boat, perhaps the largest of which is available space. Ideally, your solar panels can be installed in an area with uninterrupted sunshine. Depending on your boat type, this space may be easy or difficult to come by. While you likely get a lot of sun out on the water, the area may be too small or have too many obstacles that make fitting the number of solar panels necessary to generate your electricity needs difficult.

Consider your boat's deck or canvas when you're looking for spots to install a marine solar panel system. Remember that the positioning of your solar panels will also impact the type of equipment you should purchase – you may be able to use traditional monocrystalline and polycrystalline solar panels if you're installing on a fixed, rigid section of your boat. However, if your only open space available isn't suitable for fixed mounting, installing lower-efficiency flexible solar panels may be a better option. Some flexible solar options have an adhesive backing, so you won't need to worry about the constraints of traditional mounting and racking materials.

How many solar panels do you need for your boat?

Unsurprisingly, a yacht has very different power requirements than a sailboat. The number of solar panels you'll need for your boat not only depends on the type and size of your boat, but also the quality of the equipment you choose, how many sun-hours the boat sees, and the amount of electricity you require. Some boats can get by with one 100-watt solar panel (or even smaller), while others need a multi-panel setup.

Calculating your electricity load is the first step in determining how many solar panels you need. Below are some common appliances you may use on your boat and what they draw for power.

How many solar panels do you need for common appliances?

The last column of the above table is the amount of energy you'll consume in watt-hours running each appliance for the number of hours identified in column three. One 100-watt solar panel that receives direct sunlight for 5 hours will produce approximately 500 Wh of electricity (5 hours x 100 W = 500 Wh). Not considering conversion losses, that's enough electricity to power a mini-fridge for 24 hours or power a boat's GPS display for 10 hours. Running all of the appliances above for everyday use will require multiple 100-watt solar panels or fewer higher-wattage panels.

Install solar to save on electric bills

You can save money by installing a marine solar panel system, but you'll save even more by installing solar on your home or business. If you want to evaluate your solar options, check out the EnergySage Solar Marketplace . You can receive up to seven custom solar quotes from local installers to compare. You can also try our solar calculator for a quick estimate of solar costs and savings on your property.

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