system
Given the following post, respond as if you're commenting on Reddit:
human
What happens to the energy when a solar panel is not plugged in?

I have a small portable 14 watt monocrystalline  solar panel. I was wondering what happens to those 14 watts when it's not plugged in. Is it turned into heat in the panel or?
gpt
Tl;dr: It's dissipapted as heat.

A solar pannel works in the following way: Light is absorbed by an electron in the valence band, increasing it's energy and promoting it to the conduction band. This electron is now free to move and it leaves behind a hole in the valence band that can also move. There is a built-in electric field in the solar cell that forces holes in one direction and electrons in the other, and this can be used to force these charge carriers into a circuit and do work.

However, when the solar cell is operating under open-circuit conditions, the charge carriers (holes and electrons) have nowhere to go and pile up at the edges of the solar cell. This produces an electric field that cancels the built-in electric field in the solar cell and the electrons and holes pile up all over the cell. Now, when electrons and holes meet each other they can recombine, anihilating the electron and the hole and releasing the energy stored in the form of heat. At some point, the pile up is so severe that the rate at which electron-hole pairs are generated is exactly equal to the rate at which they anihilate and all energy is lost as heat.