It sounds miraculous to say that the right combination of metals cancreate electricity just from laying out in the sun. For anyone who’sever wondered about this, here’s a brief explanation aimed atnon-engineers.
The whole point of a solar cell is to get electrons moving. That’sall electricity is, after all, a current of moving electrons. You haveto create this by luring electrons away from the nuclei of the atoms towhich they belong. The energy from sunlight can accomplish this, but ittakes 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 surroundingatoms, giving each atom the eight outer electrons it needs forstability. (Eight valance electrons makes an atom stable and unlikely to bond.) Because it forms such stable bonds, silicon doesn’t promote theflow of electrons, making it a less than perfect conductor ofelectricity.
To improve it, you add specially chosen impurities: phosphorus, which has one more outer electron than silicon; and boron, which has oneless. Boron is added to one layer of silicon, whose lattice now ismissing 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 electronsimmediately move between the layers, generating electricity in theprocess.
Is this actually more complex? Sure it is. Some people go to schoolfor years to understand how this process and ones like it work indetail. However, it’s fun to hear a little about how an amazingtechnology works. Solar technologies are constantly improving too. Theyhave 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!