How Do Photovoltaic Cells Produce Electricity?

Wayne National Forest Solar Panel Construction
Wayne National Forest Solar Panel Construction | Image by Flickr

Photovoltaic cells are the main component of a solar panel and where the actual conversion of sunlight into electricity takes place. Photovoltaic energy, which comes from the word photo, meaning light, and voltaic, the physicist Volta, is just another word for solar energy. So how photovoltaics work?

The simple explanation of how the conversion process works is that the cells are made of a semiconductor material which knocks electrons loose when it absorbs light. The electrons are then forced to flow in a certain direction, which is direct current. The power is picked up by guides attached to both sides of the cell. Let’s see how this works in more detail.

Most photovoltaic cells are made today from a semiconductor material called silicon. Since silicon itself is a poor conductor of electricity, it is mixed with other materials.

Silicon is mixed or doped with phosphorus to produce N-type silicon (N because it is a negative charge), which carry a much better than that of pure silicon. If silica is mixed with boron, the result P-type silicon (P is a positive charge).

photovoltaic cells fabricated as a wafer, with a side is composed of P-type silicon and the other side, N-type silicon. Because the electrons makeup is different in the two silicon, when these two sides in contact with each other, an electric field is formed therebetween, resulting in a separation of the two sides.

When sunlight on the photovoltaic cell, light photons are absorbed, the knocking loose electrons in the semiconductor material. The electric field pushes electrons from the P side to the N side and keeps them flowing in reverse. The electrons are all flows in one direction, causing a direct current.

With the flow of the electron current and the voltage caused by the electric field of the cell is supplied power, as measured by wattage. In order to be used, the current must be taken into account in an electrical circuit is formed by conductors which are connected to the positive and the negative side of the cell. Then you have electricity!

The top portion of a photovoltaic cell has an anti-reflective coating to reduce the reflection caused by silicon’s polished surface. Otherwise, the cell would only think of all the sunlight shining on it.

Source: by Carol Mack


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