How Much Power Do Solar Cells Make?
Generally, we measure a solar array’s power output in watts or kilowatts of energy, and in watt-hours or kilowatt-hours per day (when estimating energy needs of a given application). Unless you are familiar with various formulas derived from Ohm’s Law (Watts = Volts x Amps) and can use this formula backward and forward, watts are not a useful method of determining power output. Since we use amps when discussing our boat electrical systems, we rate solar modules used onboard boats by their estimated electrical output, measured in Amp Hours per day. The model numbers of the Sunsei panels indicate their output (in mili-amps), so the SE-500, for example, is a 500mA charger. It is much easier to estimate what to do with 400mA than with a 6-watt panel. We arrive at these values by averaging the number of hours the panel spends in full sun (defined as 1000 watts of energy per square meter). Full sun means enough light so you see fairly sharp-edged shadows, and most locations get no more than
