It’s boating season! For those lucky enough to be out on the water, investing in solar panels is a great way to extend those trips off-shore and make the most of your holiday in your home away from home. Whether you have a sailboat, a powerboat or a pontoon boat, solar panels can help you enjoy your marine excursions even more.

Like RVs and cabins and cottages that are situated off the grid, boats do not have a stable source of electricity. Boaters tend to rely on batteries that charge when the main engine is operating or on generators. But on-board batteries have a limited capacity and generators are noisy and stinky and not conducive to a relaxing holiday. More and more boat owners are welcoming the benefits of solar panels.

From the world record holder Planetsolar at 93 kW solar capacity, to a modest single-panel installation, solar energy has something to offer for every boat enthusiast.

Planetsolar visiting Miami

Planetsolar visiting Miami (image credit: Florence8787)

How many solar panels do I need on my boat?

A modest solar power system of about 80-130 watts (consisting of one or more panels, depending on their individual capacity) will easily power lights, some electronic equipment and some other light load requirements. If you want to power appliances requiring more energy, such as a water pump, fridge, microwave, or other appliances, then you will need to consider your requirements carefully and install a larger capacity system that will meet all of your needs. In this case, 3-5 panels totaling 200-500 watts of capacity will be needed .

A more modest installation (image credit: solardave.com)

A more modest installation (image credit: solardave.com)

Watch out for shading: go parallel!

Shading is a key consideration when determining the placement of your solar panels. On a sail boat for example, you would want to consider carefully the position of the mast and sails. A good location might be the stern of the boat. Not only would the panels generate electricity, but they might also provide some much needed shade on a hot sunny day on the water. Furthermore, the installation of your panels, should you have more than one, is important as well. If the panels are installed in serial, any amount of shading on a single panel will impact the efficiency of the entire system. Installing the panels in parallel avoids this problem, as it is next to impossible to avoid some amount of shade all of the time, especially on a boat that moves around even while anchored.

Batteries, batteries, batteries: Did we mention you will need to invest in batteries?

In addition to your solar panel requirements and their positioning, you will also need to consider your battery requirements. During cloudy days when your solar panel system is not generating as much electricity, your batteries will help you maintain your comfort on your boat. The exact requirements of your batteries will be a function of the amount of electricity you plan on consuming and the amount of space you have. The less space you have available, the more you will have to minimize  power consumption so that you don’t run out of energy. You don’t want to run your batteries dry, so it’s important to build in a margin, about 50%, into your battery capacity. With batteries, it’s fairly safe to say that you get what you pay for. You want to invest in quality deep-cycle batteries. That way, your system will work optimally and you shouldn’t run out of power (another important consideration is that inactivity is very bad for a battery, so when you buy them, use them!). You will also need charge controllers. A typical small system of 100 watts should cost less than $1000 USD. Your boat will most likely have an existing battery bank, so check the voltage, capacity and other specifications of your existing batteries before you invest in new ones.

How much power can I generate during my next boating excursion?

Curious about the solar energy potential of your next destination? Whether it’s the west coast, the east coast or one of the many lakes and rivers inland, Sunmetrix Discover has the answer for you. Simply enter the location that you’re interested in, and you can easily estimate how much power you can generate for any given month.

For an inspiring story on how a couple designed and installed a 555-watt solar power system on their sailboat, check out Emily's story and photos here.

So get out there and start boating! And if you feel like it, share with us and other readers what kind of system you installed for your boat. Does it meet your requirements? Would you do anything differently? People want to know!