How does PV technology work?
Photons strike and ionize semiconductor material on the solar panel, causing outer electrons to break free of their atomic bonds. Due to the semiconductor structure, the electrons are forced in one direction creating a flow of electrical current.
Diagram of a typical crystalline silicon solar cell. To make this type of cell, wafers of high-purity silicon are “doped” with various impurities and fused together. The resulting structure creates a pathway for electrical current within and between the solar cells.
Types of Photovoltaic Technology
In addition to crystalline silicon (c-Si), there are two other main types of PV technology:
- Thin-film PV is a fast-growing but small part of the commercial solar market. Many thin-film firms are start-ups developing experimental technologies. They are generally less efficient – but often cheaper – than c-Si modules.
- In the United States, concentrating PV arrays are found primarily in the desert Southwest. They use lenses and mirrors to reflect concentrated solar energy onto high-efficiency cells. They require direct sunlight and tracking systems to be most effective.
The cost of PV has dropped dramatically as the industry has scaled up manufacturing and incrementally improved the technology with new materials. Installation costs have come down too with more experienced and trained installers.
Most modern solar cells are made from either crystalline silicon or thin-film semiconductor material. Silicon cells are more efficient at converting sunlight to electricity, but generally have higher manufacturing costs. Thin-film materials typically have lower efficiencies, but can be simpler and less costly to manufacture. A specialized category of solar cells – called multi-junction or tandem cells – are used in applications requiring very low weight and very high efficiency, such as satellites and military applications. All types of PV systems are widely used today in a variety of applications.