Solar Panels?

How can electrons keep being generated by solar panels?

• I was trying to figure out how solar panels work today and I found that electrons get displaced in 2 layers of a solar panel by photons coming from the sun to create power. If the electrons come from the solar panel and go into the electrical grid, how are they replaced in the solar panel? Wouldn't the solar panel eventually lose all of its electrons and stop working? Electrons have mass, so wouldn't the solar panel slowly deteriorate? I think solar energy is awesome and I really want to know how it works. Any help in enlightening me on this subject would great, thanks!

• Answer:

  It's because the photovolcaics are closed-loop systems. A photon will come in and basically knock an electron across what is called a "junction" and create current, but it is "caught" (really simplified version) on the other side of the junction and kind of "bounced back" into place. It's like Formula 1 racing or NASCAR. The car will be sitting in the Pit, just waiting to go, then will tear out, run a few laps until it requires more fuel, then stops in the Pit again, gets refueled, and just waits for the signal from the Pit Boss to get going again. The limiting factor on solar cells isn't the cell itself, as in the electrical circuits and semiconductors, but rather the very slow degradation of the (usually plastic) that holds each small cell in place, so that it can create a useful photovoltaic cell. Since modern plastics can be treated with UV coatings to prevent degradation, and are practically immune to water, the only thing that can really hurt them is somebody whacks it with a hammer or drops it while installing it on the roof. They're excellent. The south face of my roof is sufficient, along with a small vertical-axis wind turbine, to generate more power than I need, and it actually gets sold back to Sempra Energy/SDG&E.