Solar panels are a great addition to any DC system as an alternative charging source. Once the initial investment of purchasing and installing the panels and charge controllers has been made, there is virtually no further investment necessary. The only maintenance required is to keep the panel surfaces clean. The energy that is derived from the panels is noise, and other forms of pollution, free. The only hurdle to overcome, other than the cost of initial investment, is finding a suitable location on the boat.
A standard rigid panel is approximately 5 feet by 2 feet and rated at 140W. At full output that 140W could deliver close to 10A of DC power into the 12V electrical system. In reality it is unlikely that ideal conditions could be met to achieve theoretical output, but most of the mounting criteria should be attained to get the best possible performance from the array.
The panel should be oriented at 90 degrees to the sun rays. To achieve this on a constant basis requires that the panel tracks the sun, but reasonable results can be had by tilting the panel south with an inclination that matches the geographical latitude of the location. On a boat this can be hard to attain, so a good compromise is to “flat” mount the panel (parallel to waterline), which will provide reasonable output from the panel. The more important mounting location stipulation is that the chosen location is free from shadows. Davit arches and sundecks are good locations in this respect as they are generally shade free and also locations where the panel can be mounted out of harm’s way from physical damage. There are “shade tolerant” panels, but even those will lose output from the portion of the panel that is shaded.
PYS Electrical Technician