Question: what is the photovoltaic effect?

Peter Burgess answered on 8 Nov 2015:

It’s how solar panels work.
The easiest way to think of it is kind of like a backwards LED. LEDs take electricity in and turn it into light. Solar panels (photovoltaics) do the same thing the other way, taking light in and turning it into electricity.

It works by taking a particular type of crystal (a semiconductor) and making tiny changes to the chemistry at the surface (called doping) which means that when light comes into the crystal and gives its energy to an electron, the electron is forced to move away from where it was created. And if you move things that have charge (like electrons), you have an electric current.

The old fashioned way of making electricity is you make a big hot fire, boil up water and use the steam to drive a turbine (like a propeller). The turbine is attached to a big iron magnet, the iron spins inside a maze of copper wiring and the effect of the iron magnet on the copper makes electrons flow in the wires.

How much more complicated and wasteful is that than ‘Light hits a crystal, electricity comes out’?!