Literally translated, Photovoltaic means light-energy.  Individual solar cells are commonly called PV cells.  While the size of a PV cell varies, they are often electrically connected and encapsulated as a PV module.  Solar cells are connected as PV modules.  This creates additional voltage.  The height and length of interconnected PV modules can be several meters with a wide generating range of DC voltage and current.

Solar Cells are made from a variety of materials. Approximately 90% of PV cells manufactured to date use single-crystal silicon wafers. These are the same wafers used in the production of semiconductors. Demand for single-crystal silicon wafer sometimes exceeds supply. This results in both higher production costs and periodic solar cell shortages. A newer technology is the use of thin film deposits to perform as semiconductors on a variety of materials / substrates. Deposited thin film solar cells reduce the amount of production materials and do not require a silicon wafer. The result is a significant manufacturing cost savings. Many different materials, combinations and manufacturing processes are in development or production. Material examples include amorphous silicon, nano- or microcrystalline silicon, copper indium selenide, and cadmium telluride. Compared to single-crystal silicon wafer solar cells, deposited thin film cells cost less to manufacture but typically have lower cell efficiency ratings.

Most thin-film silicon PV cells are made from a type of silicon called amorphous silicon, which suffers from intrinsic material instabilities. This limits practical conversion efficiency to approximately 8% over large areas. During the last decade, another type of silicon, often referred to as nanocrystalline or microcrystalline silicon, has been examined as a replacement layer, or to work in tandem with amorphous silicon in a solar cell. Stable single layer nanocrystalline solar cells have been demonstrated with conversion efficiencies of 11% over large areas. Modeling has demonstrated cell efficiencies of 15% in tandem silicon cells. To date, production speed is the greatest impediment to full-scale nanocrystalline manufacture. Sencera plasma sources have demonstrated the uniform production of nanocrystalline at rates many times greater than current industry leaders.

Solar cells are evaluated on several attributes including efficiency. Solar cell efficiency is the ratio of electrical power produced to the total sunlight energy incident on the cell. Commercial single-crystal silicon wafer solar cells typically feature efficiencies between 15 – 22%. The efficiency of commercially available deposited thin film PV cells usually ranges between 6-14%. To make a better value comparison of different solar cell technologies, The U.S. Department of Energy has developed a solar cell cost model. The USDOE model converts production cost and efficiency factors into a common Equivalent Energy Cost stated in US Dollars per Peak Kilowatt hour. Based on this evaluation, single-crystal silicon wafer PV cells have an approximate equivalent energy cost of $ 0.22 per peak kilowatt hour. This is not competitive with non-renewable sources of electrical generation. Deposited thin film solar cells have the potential to reduce this cost more than 50%. Given long-term global energy demand, on-going silicon wafer supply shortage, and environmental concerns of CO₂ emissions produced by non-renewable energy sources, solar energy is poised to become a significant segment of the world’s energy generation.