Photovoltaics – History
Photovoltaics is the technology behind the most popular form of solar energy harnessing. It is the process of converting sunlight directly into electricity. The photovoltaic (PV) effect was first observed in 1839. However, it wasn’t until 1954 that scientists were able to discover exactly how it works. Historically, space programs were the biggest proponents of PV technology, as PV systems were the best source of power for satellites. Since then the industry has grown and you’ve probably all come across photovoltaic systems used in cars, homes, powering commercial buildings and even providing extra power to central power grids. Due to increased efficiency, reduced costs and increased environmental concerns, photovoltaic installations have grown rapidly in popularity in recent years.
How does the photovoltaic effect work?
A photovoltaic system uses solar panels to capture photons of sunlight. These solar panels each have many solar cells made up of layers of different materials. An anti-reflective (AR) coating on top helps the cells collect as much light as possible. Underneath this, there is a semiconductor (usually silicon) that sits between a negative conductor at the top and a positive conductor at the bottom. Once the photons are captured by the solar cell, they begin to release the outer electrons of the atoms within the semiconductor. The negative and positive conductors create a path for the electrons and an electric current is generated. This electric current is sent to wires that capture direct current (DC) electricity. Finally, the wires lead to an inverter, which then converts the direct current (DC) into alternating current (AC) electricity, which is used in homes. The more solar cells you install, the more electricity is generated.
How are solar panels installed?
Solar panels consist of several solar elements. The number and type of solar cells used depends on the resulting voltage required by the solar panel. For example, a common 12 volt solar panel will contain 36 cells. These panels are then installed in ways that capture the most sunlight. The solar installation begins with the selection of the panel type. Traditional solar panels are efficient. However, they are larger and heavier than the other two types. Thin-film photovoltaic panels are lighter and cheaper than any other solar panel, but they are generally less efficient. Concentrating photovoltaics are new and use lenses and mirrors to concentrate sunlight into solar cells. These arrays are the most efficient but can only be used in very sunny areas, such as the American Southwest. Once you have chosen the type of solar array, the next step is to choose the best location. Installers will analyze the sun’s path on a particular property and take into account any shade to choose the most efficient location for the panels. For installations in the Northern Hemisphere it is best when solar panels are oriented towards the south and not shaded at all. This way, the panels capture most of the sunlight throughout the day.
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