PV Gap

Don Said:

can a light bulb power a solar panel?

We Answered:

Yes light-bulbs work, sort of, but you have to illuminate every cell. The output is regulated by the cell with the weakest illumination.

Additionally the sun is very strong, 1000W of light or more per square meter. A light-bulb is weaker, so less output. A 100W bulb may have only 5W of light, and it doesn't cover the panel, so you can expect something like 1% of the sun's output. The spectrum of a light-bulb is actually more appropriate for a silicon solar panel, as the silicon panel responds best to red colours.

Ryan Said:

Could a light bulb give off enough light to power another light bulb via solar panels?

We Answered:

The energy from an incandescent light bulb is about 5% light, the rest heat. From a fluorescent lamp it is about 20%. The efficiency of a solar panel from 10% to 20% at converting light.

Lets say use a fluorescent lamp rated at 40 watts so 8 watts of light. The solar panel converts that to about 0.8W of electricity assuming all the light from the lamp can fall on the panel so it illuminates all the cells evenly. In practice I would say 0.1W because of difficulty of illuminating the panel with all the light evenly. We could hope to illuminate an LED, maybe a few in series, with some care. We are talking about a 12V panel here, big enough to intercept most of the light, not a single cell.

If we surrounded the lamp with properly designed curved/cylindrical panels we could get more of the available light, maybe light a small torch bulb.