Solar Panels

A solar panel or solar module is an assembly of solar cells, which can convert light into electricity. Typically a solar module consist of individual solar cells, which are electrically interconnected in a combination of a series and parallel connection. The assembly is mechanically on a backing made of steel or fiberglass and is usually covered with a glass plate. Special rugged marine-grade versions are available, which are not only very thin, but which are - to a certain degree - flexible and solid enough to be walked on.

The majority of the modules used in photo-voltaic systems use wafer-based crystalline silicon cells. These cells have a higher yield than thin-film cells, but they can only be used in rigid modules. Flexible thin-film modules are created by disposing the photo-active silicon layers on a flexible polyester film. Despite the lower efficiency, these modules offer a good price to power ratio.

The average peak power for marine solar panels is about 120 Watt-peak per square meters. As a conservative rule of the thumb, the daily average energy (Wh/day) that can be obtained from a solar panel is twice the peak power. This corresponds to 2 hours of peak power per day and a daily energy yield of 240 Wh/day per square meters. This corresponds to 20 Ah/day in a 12V system. In tropical regions due to more advantageous radiation conditions, this may be increased by a factor of two to 40 Ah/day per square meter.

On most mono-hull yachts it will be difficult to accommodate more than two square meters of solar panels. And even for this rather small area special flexible panel types will have to be used, which have a lower yield than the standard planar panels. The design of modern mono-hull yachts simply does not provide large even and un-obscured surfaces. This basically limits the daily solar energy yield to about 80Ah. The rest of the required electrical energy must be generated from other sources.