Solar Energy Logo
Solar Energy Header Image
.

Types of Photovoltaic Panels

Though the types of photovoltaic panels can be divided into a number of categories that can be daunting, there are really only four types as follows. The division of major types of solar cells is made not on materials, but rather on technology used to manipulate and extract power from those materials. For instance, silicon panels can fall into three of the four categories. While future articles will look at specific technologies or materials due to their importance in terms of market share or future market share, this article will focus on the four major strategies for extracting energy from sunlight.

Crystalline

These are what most people think about when they hear the term solar panel. These are almost exclusively constructed of crystalline silicon and are, historically, the most studied types of solar panel. Monocrystalline silicon panels have efficiencies of about 25% in most applications while polycrystalline silicon panels reach about 20% efficiency. Amorphous and microcrystalline panels fall into the thin film category below. Single junction gallium arsenide panels also fall into the crystalline category. They have an efficiency of 26%, but are somewhat more difficult to manufacture.

In terms of cost, mono-Si panels

Thin Film


Thin film cells are relatively less expensive than crystalline cells so on a cost per watt basis, even though they are less efficient, they are often more affordable. There are two basic types of thin film module, the first of which is rigid thin film and the second of which is flexible thin film.

Rigid thin film includes cadmium telluride (CdTe), amorphous silicon, and some cadmium-silicon combinations. Each cell is created on a glass substrate and then sandwiched by another piece of glass. The extra piece of glass makes these panels roughly twice as heavy as crystalline silicon, even though the active components are thinner. Flexible thin film modules are made using a flexible substrate, which is usually a form of plastic polymer.

Rigid thin film panels can reach conversion efficiencies of 6 to 12% and flexible panels slightly less. CdTe is approximately 40% less expensive than amorphous silicon, making flexible panels substantially more expensive than rigid.

Multijunction

Multijunction solar cells use more than one p-n junction in order to capture light of different wavelengths. While difficult and expensive to manufacture, these solar cells are capable of efficiencies of 40% with a theoretical maximum limit of near 90%.

Multijunction cells were originally conceived for use in applications where a high power-to-weight ratio was needed, such as satellites and planetary rovers. Over recent years, however, the extreme efficiency of these cells has resulted in more terrestrial interests due to their cost per kilowatt-hour advantage over other solar cells. As production technology progresses, the costs of these cells will decline to the point where they may not only be competitive with other solar panels, but also with grid-based traditional electricity.

Emerging Solar Technology

This branch of solar encompasses several technologies, all of which are still mainly in research and development, but hold promise. These cells stray from the traditional semiconductor-based solar panel into other, more novel electrolyte possibilities.

Light-absorbing dyes (DSSC or Dye-sensitized Solar Cells)

The advantage of DSSCs is that they are mad of low cost materials and are easily manufactured. In fact, they can even be built at home using kits. Another advantage of dye-based cells is their extreme flexibility, which makes them more durable and provides for greater application possibilities.

On the downside of DSSCs is their conversion efficiency, which is the lowest of any solar cell. Only recently have DSSCs reached the 10% efficiency mark necessary for use in commercial settings. In addition, DSSCs use liquid electrolyte, which can freeze and become non-functional at lower temperatures.

Organic Solar Cells

Organic solar cells use very thin films of biologic semiconductors, such as polyphenylene vinylene and other small organic compounds derived from living organisms in some cases. The major advantage of such systems is their extremely low cost of production. The major drawback of such systems is that maximum efficiency has only reached about 8% with current methods. The major limitations of organic solar cells may be overcome with nanotechnology in the near future, making these cells viable alternatives to more traditional systems.

Solar Panel
.
Copyright 2013 © SolarEnergy.org.uk .All Rights Reserved