Solar cell technologies differ from one another based firstly on the material used to make the solar cell and secondly based on the processing technology used to fabricate the solar cells. The material used to make the solar cell determines the basic properties of the solar cell, including the typical range of efficiencies.
Most commercial solar cells for use in terrestrial applications (i.e., for use on earth) are made from wafers of silicon. Silicon wafer solar cells account for about 85% of the photovoltaic market. Silicon is a semiconductor used extensively to make computer chips. The silicon wafers can either consist of one large singe crystal, in which case they called single- or mono-crystalline wafers, or can consist of multiple crystals in a single wafer, in which case they are called multi-crystalline silicon wafers. Single crystalline wafers will in general have a higher efficiency than multi-crystalline wafers. Silicon wafers used in commercial production allow power conversion efficiencies of close to 22%, although the fabrication technologies at present limit them to about 17 to 18%. Multi-crystalline silicon wafers allow power conversion efficiencies of up to 18%, with present fabrication achieving between 13 to 15%.

The PERL cell developed by University of New South Wales holds the silicon single junction efficiency record of 24.7%.

The efficiency achieved by a solar cell depends on the processing technology used to make the solar cell. The most commonly used technology to make wafer-based silicon solar cells is screen-printed technology, which achieves efficiencies of 11-15%. Higher efficiency technologies are the buried contact or buried grid technology, which achieves efficiencies op up to 18% and has been in production for about a decade.

Typical screen-printed solar cells.

Although silicon solar cells are the dominant material, some applications – particularly space applications – require higher efficiency than is possible from silicon or other solar cell technologies. Solar cells made from GaAs or related materials (called III-V materials since they are generally made from groups III and V elements of the periodic table) have a higher efficiency than silicon solar cells, particularly for the spectrum of light that exists in space. GaAs solar cells have efficiencies of up to 25% measured under terrestrial conditions. To further increase these efficiencies, solar cells made from different kinds of materials are stacked on top of one another. Such devices are called tandem or multijunction solar cells (the term multijunction applies to other types of structures as well). Such solar cells have efficiencies of up to 40% under concentration.

Space solar cell application.	World-record 40.7% efficiency triple-junction solar cell developed by Spectrolab.

A final class of solar cell materials is called thin film solar cells. These solar cells can be made from a variety of materials, with the key characteristic being that the thickness of the devices is a fraction of typical single or multi-crystalline solar cells. Thin film solar cells may be made either from amorphous silicon, cadmium telluride, copper indium diselenide or thin layers of silicon. The efficiencies of thin film solar cells tend to be lower than those of other devices; but to compensate for lower efficiencies, the production cost can also be significantly lower. Of these technologies, amorphous silicon is the best developed, and laboratory efficiencies are between 10 to 12%, with commercial efficiencies just over half these efficiencies. The other thin film technologies are still the subject of development, although commercial products exist. The efficiency of these devices is about 6% to 10% efficient.

CdTe module developed by First Solar.	Power plastic developed by Konarka.

Most solar cells will theoretically operate with a higher efficiency under intense sunlight than under the conditions encountered on earth. Concentrator solar systems exploit this effect, by focusing sunlight into a concentrated spot or line. Concentrator systems exist for both silicon and III-V solar cells. Silicon concentrator systems have reached efficiencies of 28% while III-V based systems have reached about 41%.

Solar concentrator developed by SolFocus.	A typical solar concentrator array.

The photovoltaic value chain is generally divided into five basic links: