So, how does a solar panel generate electricity?

A solar panel is made up of a silicon wafer that is doped with a doping material which contains an additional electron within its atomic structure that creates an excess of electrons such as phosphorus to create n-type silicon. To create fewer electrons a material with less electrons than silicon such as gallium or boron is used to create p-type silicon that then has an excess of holes useful for the electrons from the n-type material to fill if they can reach them. In effect this creates a p-n junction which has a potential difference of approximately 0.6V.

As the electrons from the n-type material attempt to fill the holes of the p-type material and vice versa this creates a barrier to any more electrons and holes passing over the barrier, this is called the depletion zone, which effectively creates the p-n junction with its potential difference of approximately 0.6V. Much like a battery if conductors are connected between the 2 layers of silicon material current will begin to flow as the electrons race to fill up the holes in the p-type material.

When photons in the form of light energy from the sun hit the surface of the panel the semi-conductor material absorbs the photon and its energy can be transferred to an electron as potential energy, the n-type silicon with an excess of electrons and via conducting strips causes electrons to flow through an external circuit in order to fill up the excess of holes on the p-type silicon and thus creates direct current flow.