Pond Boss Forums POND CONSTRUCTION Creating habitat THE BUGSLUGGER HAS ARRIVED

The power rating of the panels is of course nominal, the actual output would vary depending on vertical sun angle (as you mentioned), horizontal sun angle (time of day dependent), cloudiness, and air quality.

Perhaps you have mentioned it above, but I would measure the actual output voltage of the panels, best case (bright sunshine, high noon) and again when the sun is low. Since automotive alternators put out 14 volts or so to charge a "12 volt" battery to about 13.5 volts, I would guess your solar panels will have to put out 14+volts under at least the best conditions to fully charge the battery. Does that make any sense?