Solar Panels and the Photovoltaic Effect
Solar panels convert light from the sun into electric current through the photovoltaic effect. When photons of light strike most materials - a black leather car seat, for example - the energy causes the atoms of the material to jiggle in place, producing heat. Semiconducting materials such as silicon crystals, commonly used in solar panels, work a little differently. In these materials, electrons are shared by the atoms in the crystal lattice. Photons of light striking semiconductors in solar panels cause electrons to jump up to a higher energy level and move freely about the crystal.
The next step in making solar panels work to produce solar power is getting these electrons to flow in one direction, producing electric current. This is accomplished by adding impurities to the silicon crystal, a process manufacturers of solar panels call "doping." One part of the crystal is doped with phosphorus. Phosphorus contains one more electron than silicon and creates a net negative charge. The other part is doped with boron, which contains one fewer electron, working to create a net positive charge. When placed next to each other in solar panels, these doped crystals form a solar cell. The junction between the negatively charged silicon crystal and the positively charged crystal is known as the N-P Junction.
Initially, the extra electrons from the negative side rush to fill the empty spaces in the positive side, working until both sides reach equilibrium. The build-up of charge on either side of the junction produces an electric field which works as a one-way barrier to electrons - they can cross from the positive side to the negative side but not the other way.
When photons enter solar panels and strike the solar cell, they give the electrons on the negative side a nudge that pushes them across the junction and down an external conductor. This flow of electrons is how the silicon cells in solar panels work to produce electric current.
While solar panels do good work in harnessing the sun's energy, they do not work with perfect efficiency. However, engineers are working to improve this solar technology and build more efficient solar panels to truly capture the power of the sun.