One of the most common forms of clean energy is solar energy. It has become more popular in recent years, with solar panels appearing on rooftops around the world. Much of their appeal is due to the fact that they don’t have any moving parts that would eventually have to be replaced. Here’s a brief look at the seemingly mysterious process by which these panels convert the sun’s energy into electricity.
Photovoltaic Cells
A solar panel is essentially a collection of several cells, called photovoltaic (PV) cells. While smaller items like solar-powered radios and calculators typically require a single cell to generate the power they need, a car or house would require several thousand.
A solar cell contains several components, beginning with the two layers of silicon that make up most of the cell. The cell also contains metal plates by which electrons are guided into the home’s wiring as electricity. To close the circuit, electrons then have to flow back into the cell through its metal backing. Additionally, each cell is covered with an anti-reflective coating to ensure that the sunlight isn’t reflected away, depriving the cell of the photons it needs to initiate the process.
Silicon Layers
Although silicon is strong enough for use in a PV cell, it’s not a very good conductor. To compensate for this, manufacturers add trace amounts of phosphorus and boron to the two layers. With the added phosphorus, the top layer contains more negatively charged particles (electrons) than it normally would. To balance things out, the bottom layer with boron contains fewer electrons than it normally would.
Establishing an Electric Field
An electric field is then needed to generate electricity. The positive and negative charges in an electric field attract each other the same way the opposite poles of two magnets do. The field is created when the two silicon layers in a cell are brought together.
Extra electrons from the top layer quickly move into the bottom layer near the junction where the two layers meet. With the added electrons, the bottom layer then becomes negatively charged, while the top layer becomes positively charged. At this point, all that is needed is sunlight.
Generating Electricity
When sunlight reaches the cell, photons begin knocking electrons loose from both silicon layers. These loose electrons are then pushed out of the junction area by the electric field and onto the metal plates. As long as there is sunlight hitting the cell, the process will repeat itself, generating more clean energy.
Powering a House or Building
From the metal plates, the electrons flow as electricity to an inverter in the house or building. This is necessary to convert the direct current (DC) from the cell into the alternating current (AC) required by most appliances.
While the electricity generated by one cell doesn’t amount to very much, it accumulates when multiple solar panels are involved with many conductive wires drawing loose electrons away from the metal plates. Lost electrons eventually find their way back to the negative plate, where they will take part in the process again, creating more solar energy.