Solar cells use two layers of doped silicon, one with a surplus of free electrons and the other with holes, connected by a wire. When sunlight hits the n-type layer, it creates a current that flows through the wire to a load. The top layer is covered with glass and resin for protection. Solar cells have an efficiency of 5-15% and research is ongoing to improve this.
There are several devices that use sunlight to generate energy, but the way a solar cell works is the same. In a photovoltaic (PV) cell there are two layers of silicon, both doped, or lightly mixed, with a certain element. Typically, one side is doped with boron and the other with arsenic.
Because of the way each element bonds to silicon, the boron-containing layer, called the n-type layer, has a surplus of free electrons. The other side, the p-type layer, is deficient in electrons, called holes. The p-type layer and the n-type layer are pressed against each other and connected by a wire connected to an external load. This creates a circuit in the solar cell.
When sunlight of the right energy level hits the n-type layer, which sits on top, it excites some of the free electrons, which break away from their natural state – pairs – and flow across the boundary between the layers to create a current. . This only works if the two layers of the cell are pressed directly into each other. This is usually achieved by manufacturing both sides as part of the same process.
Current flows through the p-layer in the wire, which goes to the load, usually used to store electricity. Direct current (DC) is produced. If alternating current (AC) is desired for household appliances, the DC current is fed through an alternator.
After passing through the load, the current continues back into the n layer, which in some areas is devoid of electrons due to the current. The process continues. A current is generated without any mechanical input. Unfortunately, the materials used to make solar cells can be quite expensive.
For protection, the top layer of the solar cell is covered with a glass plate fixed with transparent resin. The whole configuration is called a pn-junction diode. More sophisticated cells use an array of pn-junction diodes.
The first solar cells were only 1% efficient. Today, commercial solar panels have an efficiency of between 5% and 15%. There are currently millions of dollars going into research to improve these rates.
Protect your devices with Threat Protection by NordVPN
