Science Buddies: "Ask an Expert"

I have a 20% efficient solar cell. what happens to the 80% of the energy that is not used? I know some of it is converted to heat and some is reflected but i need percentages and i need to know what if anything else happens to it. thank you so much

ghebner - You are correct in your assessment. Energy that is not converted to electricity is going to be reflected back, the rest converts to heat in the mass of the solar cell. Determining those percentages will be tricky, but can probably can be closely estimated.

Rick Marz

This would be an interesting experiment that you could perform. A light meter could determine the power coming in. A multimeter could determine the power coming out in electricity. And a thermometer could be used to determine how much the cells heat up while exposed to the light (this would be the trickiest thing to measure, because there are a lot of factors in there, and it would be hard to make it work in a closed environment... an interesting challenge in experimental design). The remainder would be what was not absorbed by the cell (i.e. reflected, effectively).