Dabel wrote:How efficient is solar power in converting light to electricity? I am wondering so I have this hypothetical experiment.

Suppose I rigged up a 1.5kW system (9 panels) in a dark room and then rigged up a search light over the panels drawing (say) 1.5kW of power to run. Now if I ran the search light for 10 hours (using 15kWh) what power would the panels generate?

Just curious about the physics involved.

Well if you used high efficiency compact flourescent globes you might get somewhere?

As advised earlier you might loose 20% in the transfer efficiency of the panels so 1.5kW might need 1.8kW in.

If we use 18w compact flourescents that give off the same light as a 60W globe we would produce the same amount of light as as 1.8kW of globes by lighting the panel with 30x 18w compact flourescent globes ie 30x60W = 1.8kW, and of course this would only consume 30x18W= 540W.

If 1.8kW of solar power into the solar panel resulted in 1.5kW of power out, then 540W of these compact flourescent lamps is equal to the light output of 1.8kW of the globes, and clearly again, with 1.8kW solar power in and 20% in-efficiency, we have already shown you will get 1.5kW electrical power out.

Of course this difference only becomes greater as energy measurement with each hour of power (kW) becomes energy (kWh) and more glaring a difference with multiple hours, despite putting out the same amount of light as 1.8kW of incandescents, we would only be using just of half as much energy per hour!

So based on the above calculations you have either now proven energy is not a constant in physics and just invented the perpetual motion device, or more likely that my mathematics are very misleading but simply offered in jest and fun and tongue in cheek -following more serious and correct answers above.

There will always be losses in the conversion from electricity to light/heat, and losses in the conversion of light/heat back to electricity.

regards

Sojin Muneshi