Photovoltaic panels (aka solar panels, PV panels, etc) are made up of individual cell that cover the panel. Those cells are made out of semi-conductor materials like silicon. There are two layers to the cells, a N-type silicon (negative), and a P-type silicon (positive). The N-type silicon contains phosphorus, which helps produce more negative electrons than the pure silicon usually would. The P-type silicon contains boron, which helps produce more positive protons. When the photons of light from the sun hit both of these layers, the positive and negative charges are released by the semi-conductor material, and then routed through the system to be used in the electrical load of the structure.