Make: Volume 82

multiply panel watts × average hours of sunlight ×

75% (as it is unlikely to be at full efficiency):

250 watts × 5 hours × 0.75 efficiency

= 937.5 daily watt-hours.

And then convert it to kWh like our electricity bill:

937.5 / 1000

= ~0.94kWh per solar panel.

Your panel will usually tell you its voltage output,

but that indicates the performance of the panel

in ideal conditions. A great exercise is to take

your panel outside, connect a multimeter to the

panel’s positive and negative leads, and turn the

meter to the voltage reading setting. As you

move the panel, you can clearly see how the

voltage output is being affected (Figure

E

).

You can ...