People regularly ask us about solar panels, and they often think that they can be quite independent with a just few panels on the roof. This, however, is not as true as people think. If you ask the manufacturers, they will generally discount the effectiveness of them between October and March due to the height of the sun in the sky, the length of the days, how clean they are kept, frost, shading, and shadows.
Panels are, however, a great help as the seasons change, and with some of the summers that we have had in more recent years, they have worked to expectations.
If you would like to fit Solar Panels to your boat, what do you need to know?
1. Where can I mount them?
Obviously, they will be mounted on the roof, but the best plan is to find out the sizes of different power panels available and then get your tape measure out and see what you can fit where. You don’t want to obscure a roof hatch or have something opening on top of them. Keep reasonable access to anything else that you store on the roof, and make sure not to block any ventilation.
2. How many can I have?
Generally the more, the better. Systems work best when all the panels in it are the same size and from the same manufacturer.
3. How should I mount them?
To get the absolute maximum from the panels, you need to move them in order to follow the sun. During the summer, the gain from this against mounting them flat on the roof is negligible, but during the winter months, there are gains to be had from mounting at an angle.
4. Where do I put the cables?
The cables, as with any electrical installation, need to be the shortest they can practically be. However, if the only space on your boat is at the front, then the cables will have to come all the way back to the batteries. Do you leave the cables outside along the roof, or bring them inside and discreetly hide them? Loose on the roof is cheaper and easier, but special gland fittings are available to bring the cables in through the roof if that is what you choose to do.
5. What Regulator do I need?
A couple of choices to start with are PWM or MPPT. PWM are the earlier regulator that has really been superseded by the MPPT. MPPT stands for Maximum Power Point Tracking, and using this type of regulator, you generally get 30% more power from the same panels.
6. Can I fit them myself?
As with anything electrical, only undertake work that you are confident and knowledgable about doing. Although, panels are quite a simple installation, always ask professional advice. Depending on the number of panels and type of regulator, you could be working with over 100 volts DC (for comparison, 100 volts AC is mains power in the USA!)
The higher the voltages, the more dangerous an installation can be.