Charging with a Solar Panel

[Sue & Larry]

If a solar panel is used to charge your battery, do you need a voltage regulator and an inverter/charger, or can you just use a inverter/charger like a Hart 2000?

Sue & Larry respond:
When charging 12-volt battery banks with alternative energy sources like solar panels, a voltage regulator, or charge controller is always a good idea. In simplest terms, a charge controller senses your batteries state of charge and either turns on or off the current from your solar panel depending upon its findings.

Without a method to regulate your charging current, your panels would continue to charge your battery bank even when the bank was full. The result would be gassing your battery, reduced performance, and a shortened battery life.

Some solar panels claim to be self-regulating, but their voltage is usually lower than you would want for charging a house bank on a sailboat. We’d stay away from these types of panels.

Assuming you were on your boat full-time, you could physically unhook your panel as your battery bank approached full charge. This would eliminate the need for a charge controller and ensure that your batteries didn’t overcharge. We think that this is kind of a dumb idea though, since the beauty of alternative energy is that it’s quiet, never-ending, and self-tending.

On Serengeti, we’ve not plugged into shore power now for two-and-a-half years. Our five solar panels and one wind generator have provided us the freedom to travel where we want, and to stay for as long as we choose. We’re a completely self-contained unit, except for food, beer, and wine. You might want to check out our article, Choosing and Installing Solar Panels. It's right here at SailNet.

The Link 2000 by Heart combines a sophisticated battery monitor with a remote-control unit for their inverter/chargers. This product will not suffice as a charge controller for your solar panel. We do believe, though, that every cruising boat should include a battery monitor as standard equipment. For most, the smaller and less expensive Link 10 works fine. If you want more features and have a desire to remotely control your inverter, the Link 2000 is tops.