What size panel will MAINTAIN a single car size battery, or a deep cycle marine?
A 2.5 watt Solar Maintainer is appropriately sized for maintenance levels on these batteries. It is not large enough to overcharge, and doesn’t require a controller, but is large enough for a maintenance level charge. These and the 1 watt and 5 watt have a built in diode to prevent feedback through the panel at night, one of the functions of a solar controller. If there is any sort of drain on the battery like an onboard computer, bilge pump, alarm, etc., a larger panel sized to compensate for the drain is required.
