Photovoltaic Cells and Arrays

Background

The PV cell is the basic unit in a photovoltaic (PV) system. An individual PV cell typically produces between 1 and 2 watts, hardly enough power for the great majority of applications. But we can increase the power by connecting cells together to form larger units called modules. Modules, in turn, can be connected to form even larger units known as arrays, which can be interconnected for more power, and so on. In this way, we can build a PV system to meet almost any power need, no matter how small or great.

From Cells to Arrays: A Closer Look

Modules or arrays, by themselves, do not constitute a PV system. We must also have structures on which to put them and point them toward the sun, and components that take the direct-current (dc) electricity produced by the modules or arrays and condition the electricity so it can be used in the specific application. These structures and components are referred to as the balance of system (BOS).

The solar cell is the basic building block of a PV system. Individual cells can vary in size from about 1 cm (1/2 in.) to about 10 cm (4 in.) across. However, one cell only produces 1-2 W, which isn't enough power for most applications.

Figure 1. The basic photovoltaic cell typically produces only a small amount of power. To produce more power, cells can be interconnected to form modules, which can in turn be connected into arrays to produce yet more power. Because of this modularity, PV systems may be designed to meet any electrical requirement, no matter how large or how small.

A module typically consists of several solar cells, although thin-film materials like amorphous silicon and cadmium telluride can be made directly into modules, effectively bypassing the solar cell. These two silicon modules are rated at approximately 50 W each and provide power for a street light using 12 V battery storage. Modules such as these can also be connected into arrays for more power.

Arrays are the large power producers and consist of several modules. They can be used to provide up to several megawatts of electric power.

Source: U.S. Department of Energy Photovoltaics Program.

For more information on this source please visit National Renewable Energy Laboratory

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