It sounds miraculous to say that the right combination of metals can create electricity just from laying out in the sun. For anyone who’s ever wondered about this, here’s a brief explanation aimed at non-engineers.

The whole point of a solar cell is to get electrons moving. That’s all electricity is, after all, a current of moving electrons. You have to create this by luring electrons away from the nuclei of the atoms to which they belong. The energy from sunlight can accomplish this, but it takes a certain combination of elements to make it work well.

You start with a semi-conductor like silicon that forms a stable lattice at the atomic level. It shares its four outer electrons with surrounding atoms, giving each atom the eight outer electrons it needs for stability. (Eight valance electrons makes an atom stable and unlikely to bond.) Because it forms such stable bonds, silicon doesn’t promote the flow of electrons, making it a less than perfect conductor of electricity.

To improve it, you add specially chosen impurities: phosphorus, which has one more outer electron than silicon; and boron, which has one less. Boron is added to one layer of silicon, whose lattice now is missing some electrons, and phosphorus is added to a layer above it, which now has extra. The intersection of these layers is called the P-N Junction. When sunlight adds energy to this system, the extra electrons immediately move between the layers, generating electricity in the process.

Is this actually more complex? Sure it is. Some people go to school for years to understand how this process and ones like it work in detail. However, it’s fun to hear a little about how an amazing technology works. Solar technologies are constantly improving too. They have already grown more efficient and less expensive. The evolution is a fun process to watch — and it’s even better to be a part of it by using solar yourself!