Photovoltaic solar panels are packaged photovoltaic cells (or solar cells) connected together to produce a certain amount of electricity. A photovoltaic cell is a kind of photoelectric cell which makes use of the photovoltaic effect to produce electricity. The photovoltaic effect is a process by which a voltage is created whenever electromagnetic radiation touches photovoltaic materials. The panels are the main components of photovoltaic solar systems which produce electricity for various purposes.

Traditional photovoltaic solar panels are made up of crystalline silicon (a material with semi-conductive properties) solar cells. Cells made from this material have efficiencies of 11-16%, which is one-half to two-thirds of the computed maximum efficiency. The process of making solar cells using crystalline silicon was developed as a result of the advancements in the microelectronics industry which has a lot of emphasis on semiconductors.

Crystalline Silicon – The Heart of the Photovoltaic Solar Panel

There are two types of crystalline silicon used for making photovoltaic solar panels: monocrystalline and multicrystalline. Monocrystalline silicon is produced by slicing wafers of up to 150 millimeters in diameter and 350 microns in thickness from a crystal boule (synthetically made single-crystal ingot) of high purity. Multicrystalline silicon is made by first cutting a silicon block into bars and then into wafers. For both types of crystalline silicon, a semiconductor junction is created by making phosphorous diffuse onto the upper surface of the silicon wafer which is doped with boron. The front and the rear of the cell are applied with screen-printed contacts; the front contact pattern allows the silicon to have maximum light exposure while minimizing electrical losses within the cell.

Since crystalline silicon is expensive, the solar industry sought for other materials for photovoltaic solar panels. This search led to the creation of thin-film solar cells which are more efficient, less expensive and lighter but more durable than crystalline cells. The materials for this kind of solar cells are strong absorbers of light such as amorphous silicon (a-Si), another form of silicon; and copper indium (gallium) diselenide and cadmium telluride which are both polycrystalline materials. All these materials are amenable to large area deposition, resulting to lower manufacturing cost. Of the three, the most well developed for use in thin-film technology is amorphous silicon. The downside to thin-film photovoltaic solar panels is that their efficiencies degrade faster over time compared to their crystalline silicon counterparts.

The Photovoltaic Effect

Photovoltaic solar panels produce electricity through the photovoltaic effect. When a photovoltaic material like silicon is exposed to electromagnetic radiation, electrons are knocked off it. Due to the electric field in the material, these electrons move in a directional current. If these electrons reach another material, especially a conductor, a certain voltage builds up. This voltage is now the electricity observed from the panels.

Photovoltaic solar panels produce direct current (DC) electricity which is converted to alternating current (AC) by the inverter in photovoltaic systems. Most appliances run using the AC current. The amount of power generated by photovoltaic systems depends on the number and the type of solar cells they contain as well as the location where they are installed. The main advantage of using this kind of power source is that the energy it produces is clean and its raw material – sunlight – is unlimited.