Question about the concept of electricity in solar cells.

[LogicX]

Ok so I understand how a voltage source works, with electrons flowing from a high potential to a low potential. But I'm a little confused about solar cells. So the way they work is that an incoming photon strikes an electron and gives it enough energy to break free and create a current. But how do the electrons get replenished? Why does material not run out of electrons? Does it yank off electrons from surrounding air? If so, would running a solar cell in a complete vacuum eventually stop producing electricity?

Or what about, say, a power generator from a waterfall. As those turbines turn and release electrons, how do the electrons get back? Is there just a positive electric field surrounding any material being used like that?

If I am right, is this something that has to be accounted for? Like, you are doing a calculation to determine the output of a solar cell, but you have to take into account that at any given time there are going to be a less than ideal amount of electrons in the material to create a current?

Just something I have been thinking about for the past couple days, thanks!

 

[Antiphon]

There's always two wires; electrons go out one wire and the same number come in the other.

 

[LogicX]

Where is this endless supply of electrons coming from?

 

[Antiphon]

They are the ones that are already there and simply being pushed around in a circle around the circuit.

 

[JaredJames]

Imagine a pump with a hose running from the output and looping around to the input.

As it pumps, the same water goes round and round.

 

[LogicX]

Ah, silly me, for some reason I was thinking of the electrons as actually having to go somewhere else to do work.

You know, I think that is one of the shortcomings of intro physics. They teach you all about equations and how to calculate different values about circuits and such, but they don't ever teach useful things like "this is how a current makes a motor turn", and it leads to misconceptions like I just had.