PV Gap

Leah Said:

if I have a light bulb 60W replacing sun light on a solar panel and I take a reading of anything from 13v to?

We Answered:

The idea of using solar energy is that it comes for free, after the cost of the panel.

Using a light bulb to power a solar panel uses more energy than directly charging the battery. A light bulb is only 10% efficient, loosing most of its energy through heat. A solar panel is only 13% efficient, converting only a small part of the energy to electricity. There are just too many losses in the system. You are burning 60 watts to get about .78 watts of energy to your battery.

So, unless the light bulb is always on, at someone else's expense, such as at work, then it is not worth-wile.

I can charge my little solar pocket charger at work off the fluorescent lamps that are always on anyway, for example.