Peripherals
While the PV panel is the power-producing element of a system, the other components involved are equally important to optimum performance. Charge controllers are the next most critical piece of the assembly. Solar panels typically produce power at higher voltages than can be sent directly to the batteries. High-performance panels can produce as much as 30V per panel. Batteries want an optimal voltage input for charging just above static voltage. Too little won’t charge and too much will damage the batteries. The charge controller’s job is to regulate the voltage coming out of the solar panel to match the batteries’ needs. The controller also prevents the panels from draining the batteries when they are not producing power.
The two types of controllers most commonly used are pulse width modulation (PWM) and maximum power point tracking (MPPT). PWM controllers read the battery voltage and match the output from the solar panel to that voltage. However, they do this by pulling down the panel voltage in the process. An MPPT controller also reads the battery voltage, but instead of pulling down the higher voltage of the panel to match the battery voltage, it converts the residual voltage into higher amperage going into the battery. This use of the excess panel voltage increases the output of the solar system.
With proper wiring and fuse placement, a system could be complete with these simple components, however, equipment manufacturers have also created devices for monitoring the system. These monitors can tie together all of the components, from analyzing the state of the battery bank—including Ah used and Ah remaining—to voltage output readings from the panels. Sophisticated ones will also allow control of the inverter and generators, and they can even be set to start a generator when the battery bank reaches an established level of discharge. The more advanced monitoring devices also allow remote control and monitoring from web-based applications when connected to the boat’s Wi-Fi network.
How you use your boat drives many of the decisions you make, whether to install a small solar panel to maintain a battery on a moored boat, or a high-power solar array that meets all or most of a boat’s electricity needs.
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