Solar PV panel is the key component of any solar photovoltaic system, which takes the sun’s energy and converts it into the electrical current.
The process of converting light (photons) to electricity (voltage) is called the solar photovoltaic (PV) effect. Photovoltaic solar cells convert sunlight directly into solar power (electricity). They use thin layers of semi-conducting material that is charged differently between the top and bottom layers. The semi-conducting material can be encased between a sheet of glass and or a polymer resin. When exposed to sunlight, electrons in the semi-conducting material absorb the photons, causing them to become highly energized. This movement of electrons between the top and bottom surfaces of the semi -conducting material generates a current known as a direct current (DC). The efficiency of solar panels goes hand in hand with purity, but the processes used to enhance the purity of silicon are expensive. Efficiency should not be your primary concern. As you will later discover, cost-and space-efficiency are the determining factors for most people. There are three main types of solar PV panels.
Mono crystalline PV cells:
This type of solar cell is made from thin wafers of silicone cut from artificially grown crystals. These cells are created from single crystals grown in isolation, making them the most expensive of the three varieties but they have the highest efficiency rating of up to 21%.
POLY CRYSTALLINE PV CELLS:
This type of solar cell is also made from thin wafers of silicon cut from artificially grown crystals, but instead of single crystals, these cells are made from multiple interlocking silicon crystals grown together, hence they are cheaper to produce, but their efficiency is lower than mono crystalline solar cells, currently at about 18% maximum.
THIN FILM / AMORPHOUS PV PANELS:
Amorphous silicon cells are made by depositing silicon in a thin homogenous layer onto a substrate rather than creating a rigid crystal structure. As amorphous silicon absorbs light more effectively than crystalline silicon, the cells can be thinner – hence its alternative name of ‘thin film’ PV. Amorphous silicon can be deposited on a wide range of substrates, both rigid and flexible, which makes it ideal for curved surfaces or bonding directly onto roofing materials. This technology is, however, less efficient than crystalline silicon, with typical efficiencies between 6 – 12%, but it tends to be easier and cheaper to produce. If roof space is not restricted, an amorphous product can be a good option. However, if the maximum output per square meter is required, one should choose a suitable crystalline technology.
A number of other materials such as cadmium telluride (CdTe) and copper indium selenide (CIS) are now being used for PV modules. The attraction of these technologies is that they can be manufactured by relatively inexpensive industrial processes, in comparison to crystalline silicon technologies, yet they typically offer higher module efficiencies than amorphous silicon. Most offer a slightly lower efficiency: CIS is typically 10-13% efficient and CdTe around 8 or 9%. A disadvantage is the use of highly toxic metals such as Cadmium and the need for both carefully controlled manufacturing and end-of-life disposal; although a typical CdTe module contains only 0.1% Cadmium, which is reported to be lower than is found in a single AA-sized NiCd battery.