Solar Panels on Boats (Are They Worth It?)

With gasoline prices through the roof and with everyone trying at least to be more energy aware, many boat owners are considering using solar panels on their boats.

From fishing boats to superyachts, owners are using the best marine solar panels to help run entire systems or just keep batteries charged. How that power is used, how big of a solar panel array is needed, or even if it is worth it, depends on several variables.

Since solar panels and associated equipment have gotten more efficient and affordable, they are an option for just about every boat owner.

The following are key questions that must be answered to make an informed decision and get the most out of a boat solar panel kit possible:

  • Can solar panels be used on boats
  • How many solar panels do boats need
  • What size solar system for a boat
  • Marine batteries and solar
  • FAQ for solar and boats

Below, each of those questions is addressed as well as advice given on how to decide if solar power works for your boat and the best way of implementing a solar panel power system.

Solar panels on a boat

Can Solar Panels Power a Boat?

The short answer is “yes,” but with some stipulations. First, most solar panels are not used to “power a boat.” Solar panels charge the batteries that help start powerboats as well as any auxiliary systems like refrigeration, communications, etc.

The benefit of solar panels on a boat are:

  • Charging the boat main and trolling batteries
  • Can be configured to store energy to power secondary systems (appliances, electronics, auxiliary lighting, etc.)
  • Can maintain batteries if a boat is sitting idle
  • Can create power to recharge chargers
  • Can be used with non-boat equipment like camping equipment
  • Serve as a charging source for dead or weak batteries
  • Serve as a source of power if the main power systems fail

With smaller boats, the goal is to keep the battery charged. With larger boats, the goal is to help alleviate the need for the boat’s engine to provide power. 

How Many Solar Panels Do I Need to Run a Boat?

This depends purely on how you use your boat, what power needs you have, and the storage space you have on your boat. Here are three examples:

Pontoon Boat: A pontoon boat would use electricity to start the motor, run lighting, and possibly other electronics like a sound system. Occupants may also need the power to charge individual electronics. 

The power needs on this would be minimal outside of keeping the motor battery charged. A boat like this would likely need minimal solar panel needs.

Bass Boat: A boat like this would have power needs with the main battery, trolling motor battery, lighting, and live well, plus any electronics like smartphones, GPS and mapping devices, and at least a basic fishfinder system. 

Houseboat: The needs of an average houseboat are substantial in regards to systems, appliances, main motor battery, etc. 

It is likely at the least, power is needed for a refrigerator, stove, pump for water, internal and external lighting, keeping the main batteries charged, navigational equipment and any other personal device power needs. 

Solar panels on a boat docked

Are Solar Panels on a Boat Worth It?

The answer to that question depends on two key factors:

  • Why do you want to use solar panels on your boat
  • How much do you want to spend

If your motivation is environmental or energy use-related and not purely financial, then using solar panels to help power your boat is an easy decision to make.

If finances or potential financial savings factor into your decision, you then must consider the following:

  • How much would you use solar panels on your boat?
  • How much do you use your boat?
  • What type of solar panel system array would fit your boat?

The answers to those questions can help you determine if solar panels are worth your time and money.

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How Do You Size a Solar System for a Boat?

As mentioned, figuring out the size system you need, requires calculating power use, adding other operational factors, and converting those totals to solar panel energy output capacity. 

The additional factors include the following:

What You Are Powering

If you are running a sound system and basic lighting, your solar panel needs are going to be much less than if you are using your solar panel array to power your navigation system, lighting, and appliances. 

Size, Shape, and Space

The size and style of a boat often determine where a solar array will fit.

Boat Usage

Another consideration is your boat usage. If you only occasionally go out on your boat, you will not need much of a solar panel display. If you go out every day or every weekend, you need to create more power. 

Sun Hours

The amount of time your solar panels are usually exposed to daylight factors in as well. 

Figuring Out Your Power Needs

To assess your power needs, you first need to document what you use and how much power per hour those things use. 

Calculating Daily Average

A 60 Watt lightbulb used for 6 hours will use about 360 Watt/Hours in a day. A bilge pump uses about 40 Watts an hour and will be used for one hour a day. 

A TV runs typically at 200 Watts per hour, which means if you played it for four hours, you would have 800 Watt/Hours used in one day. 

That means your daily total wattage for that day for those pieces of equipment or system would be 1,360 watts per day.

Average Solar Panel Output

Most solar panels produce between 100 to 400 watts per hour. That figure, however, is based on optimum conditions. The actual output might vary from manufacturer estimates, depending on how much sun exposure and time in a day you can be converting solar to electricity.

Bringing it Together

Take your average daily power usage at 10 percent. That gives you 3 percent to account for differences in the estimated output and seven percent to handle spikes in power needs.

Solar panels on the roof of three boats

Can a Solar Panel Charge a Marine Battery?

Yes. For most marine batteries, a solar battery charger 12-volt marine keeps one marine battery fully charged when the boat is not in operation. 

Specific Requirements

Most marine batteries are 12 volts. Larger vessels have larger batteries, more storage capacity, and can handle larger solar arrays.

Solar panels and system components can be purchased as a kit or separately. Most dealers that sell either have an expert on hand to help you with any questions.

How Does a Solar Panel Work on a Boat?

The solar panel system is pretty simple outside of converting solar rays into usable power. 

Depending on power needs, a solar panel system can have the following:

  • Solar Panels based on needs calculations
  • Charge Controller
  • Inverter
  • Battery or battery bank
  • Floating solar panels for boats that are smaller

The Process

Sunlight hits the solar panel creating an electrical current. The current flows into a battery for storage. The charge controller regulates the current capacity of each battery so the battery does not become overcharged. 

Depending on power needs, a solar energy system may have an inverter to convert from direct to alternating current. 

How Long Do Boat Solar Panels Last?

A good baseline for module longevity is about 25 years, which is the average performance guarantee warranty for most panels provided by panel manufacturers.

Most solar panel performance warranties guarantee 90% of maximum output at ten years and 80% at 25 years.

In terms of runtime for a boat, that depends on how much solar energy you can convert, how much power you can store, and what your power needs are. The way to calculate that is:

Figure out your average daily power needs and solar energy production capacity and subtract the two.

For instance, if you require 2400 watts per day and your solar panel system produces 2400 watts of power a day, you have enough power to last you all day. If you have a battery bank to store power, you can run the same power that needs longer.

How Fast Can a Solar Panel Powered Boat Go?

The solar panel has no impact on speed if the boat’s marine battery and motor work correctly. All the solar panel array does is create energy to recharge a battery.

The battery charge transfers to a marine battery via a charge controller.The motor capacity and type of boat determine its speed thresholds.

How Do You Install Solar Panels on a Boat?

You have a few options to get the optimum marine solar panel kit installation.

  • Hire a professional installer and let them handle the design and installation
  • Design it yourself and use that to create an installation plan
  • DIY with no plan and “re-engineer” the process working back from the marine battery (not recommended.)
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The wisest move is to hire someone to do the installation for you. If you DIY, however, create a plan and ask a solar panel installation professional to review it. Then follow the plan completely.

Solar Panels For Boats FAQ

How Much Does a Solar Boat Cost?

It is impossible to give an accurate estimate without making some pretty significant assumptions because every boat has different needs and abilities to accommodate a solar panel array, inverter, and power storage units. 

Additionally, solar panel use makes a huge difference in what is needed and thus the overall price. 

How Do You Charge a Marine Battery With a Solar Panel?

Once your array, battery bank, and charge controller are hooked up and calibrated, park your boat where it can get hours of sunlight and let the bank store the charge. Once that reaches the manufacturer’s recommendation for stored power, activate the charge controller.

It will automatically control the charge to your marine battery and stop once it has reached full load.

What Size Solar Panel Do I Need to Charge a Marine Battery?

For a small boat, you can use any panel that exceeds about 20 watts will do if you have sufficient sun exposure. You will need larger capacity panels for larger vessels. Consulting an expert on what size you should use is the best approach. 

What Size Solar Panel Do I Need to Trickle Charge a 12 V Battery?

The size panel you need to trickle charge a 12 V battery is the same as the question above. A small boat solar panel kit that produces as little as 20 watts can work with a trickle charge for a smaller boat. A larger boat needs more and larger solar panels to charge quickly. 

How Do You Hook up a Solar Panel to a Boat Battery?

You do not. You hook the solar panel to a lithium battery for the storage of power. The battery bank connects to a charge controller. The charge controller attaches to your battery. The controller ensures you do not overcharge your marine battery.

Can You Run a Trolling Motor Off A Solar Panel?

Yes. You run a trolling motor off a marine battery and charge the marine battery through the solar panel, depending on the design you implemented. 

Are There Solar Powered Yachts?

Yes. Yacht solar panels are being implemented as much or more than on smaller boats. 

Sources:

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