Solar cell technology has been in existence for over 60 years. Solar modules, commonly referred to as photovoltaic panels, have been used to generate electricity from light ever since the silicon based semiconductor was invented. No longer a laboratory curiosity, solar cells are an industry unto themselves and are as common in energy generation as conventional power generation methods such as steam turbine driven generators and nuclear power plants. There are many solar energy collection methods in use and available today. We will investigate the more common electricity producing solar energy devices: photovoltaic cells and PV modules.
Solar cells are made of materials that are electrically activated when light strikes their surfaces. This unit, a solar cell, operates without moving parts and never wears out! Add many cells together and you have a solar array or a photovoltaic module Solarlight. The more cells, the higher the power that is possible to generate from the modules.
The top layer of the solar cell or wafer contains a silicon layer which has free electrons which are negatively charged particles. A boron enhanced bottom layer contains spaces or holes, that let electrons move into the open spaces. The manufacturing process creates this electron imbalance between the two layers within this semiconductor material. This imbalances is responsible for the operation of the solar cell which creates the electrical current and voltage.
Photons from the sun hit the outside of the photovoltaic cell. This activity excites the free electrons in both silicon layers. Some electrons in the bottom layer travel to the silicon layer at the top of the cell. Electron flow moves through metal contacts located on the solar cell’s front and back which creates electricity. Electrons flow in a closed loop or electrical circuit. Combining multiple solar cells has an additive effect on voltage and current depending on how they are “strung” together. Think of each cell as a battery. Stringing the cells in series (negative to positive) will add voltage and keep amperage the same as for one cell. Stringing the cells in parallel will keep voltage the same as for one cell but add the amperage of the cells.