Frequently Asked Questions
What Are the Benefits of Solar Panels on Boats?
Installing solar panels on your boat can provide quite a few key benefits, although the perks you’ll actually experience depend on your situation and your specific boat.
Perhaps most importantly, solar panels can charge your boat’s battery and maintain electricity for emergencies. Most systems — even small ones — can serve to charge your phone, GPS or other emergency devices in case you run into problems out on the water.
Larger systems can also provide power for recreational use, like charging phones, powering speaker systems, keeping beer cold and more.
How Many Solar Panels Will You Need On Your Own Boat?
The first step when figuring out how many panels you need is to figure out your boat’s power requirements. Creating an excel or google sheet, or using this sheet, is the best way to organize this.
Add up all the energy used by each device on your boat, such as the fridge, lights, computers, etc. by checking the badge on the appliance to give you the power requirements in watts or amps. You will want to use either all watts or amps when making your computations, and match it to the solar panel’s quoted output.
Next you want to calculate all of the watt-hours or amp-hours of each device – get the watt or amp output of each device and then multiply it by the hours per day the appliance will be running.
When making estimates, take into account that some appliances will work harder during certain hours – for instance, the fridge will work harder when the sun is out and the temperature rises, or you will use your watermaker more should there be more guests onboard.
You will also need to calculate how much power you can reasonably expect to get from your panels over 24 hours, and ensure that the panels are powerful enough to supply your complete power requirements in the daytime, plus have enough capacity to charge the battery by the amount it has been depleted overnight.
Once you’ve figured out your energy requirements, you should add at least an extra 10% margin for expansion and errors. Underestimate your power needs and you will end up having to run the engine to top off the batteries every so often.
Worse comes to worst, you can always add another panel or two later. Power usage fluctuates, and is hard to predict. After cruising, you should get a better idea. And keep in mind – a bit more is always better than a bit less.
Will Solar Panels Keep My Boat Battery Charged?
Yes, solar panels can be hooked up to keep your boat’s 12 volt battery charged. However, you need to make sure you install a system that is sized appropriately for your boat’s needs.
You can check how much power your boat draws from its battery system by looking at the loads (in amps or watts) of each device. You can also use your battery monitor if you have one to check the energy demand of each individual component pulling power. Then, choose solar panels that produce a bit more energy than your system needs.
If you live in an area that experiences a lot of cloudy weather, you might want to size up your system even more to ensure your system generates enough electricity.
How Long Does A 100 Watt Solar Panel Take To Charge A Marine Battery?
Depending on the charging capacity, it will take around 4-20 hours to charge a 12V battery with a single 100W solar panel. If you want to charge the battery fast, you can increase the number of solar panels you use for charging.
What Is The Difference Between a 12V And a 48V System?
The voltage refers to the battery bank's capacity. A 12V system has lower voltage but higher current, which is suitable for small setups. A 48V system has higher voltage and lower current, and experiences lower energy losses in the form of heat (due to reduced current flow), resulting in an overall more efficient system.
How to Get the Most out of Your Boat’s Solar Panels
Bear in mind the following tips to maximize the energy your solar panels will produce:
1) Keep your panels as perpendicular to the incoming sun’s rays as possible: All panels will produce more power if they get direct sunlight. Mount your panels as best possible so they can be aimed in the appropriate direction, no matter what the season, course, or latitude.
2) Consider shadows when placing your panels: The output of a panel drops dramatically when under a shadow, even if only 10 percent of the panel is covered. A small shadow can reduce the panel’s output by 50 percent or more. When something as large as a boom, radar scanner, or mast casts its shadow on a panel, your output goes down dramatically.
3) Keep your panels cool: It’s not easy to keep a black surface cool in the sun, but panel output can go down as the temperature rises, so if you can provide some ventilation on the backside of the panel, you may be able to pick up a decent increase in energy production. The colder the panel, the higher the output. For instance, a solar panel’s performance on a clear, cold winter day can be 30 to 40 percent over rated specs!