en.wikipedia.org/wiki/Solar_cell en.wikipedia.org/wiki/File:PVeff(rev100921).jpg The chart illustrates the best laboratory efficiencies obtained for various materials and technologies, generally this is done on very small, i.e. one square cm, cells.Commercial efficiencies are significantly lower. A low-cost photovoltaic cell is a thin-film cell that has a price competitive with traditional (fossil fuels and nuclear power) energy sources. This includes second and third generation photovoltaic cells, that is cheaper than first generation (crystalline silicon cells, also called wafer or bulk cells). The Solar grade silicon shortage in 2008 made thin film solar more attractive, however with the increase in raw silicon production, many manufacturers have decided to stop producing the far more inefficient thin film cells in favour of expanding production on crystalline solar cells, which places even more downward pressure on crystalline cell prices.
Grid parity, the point at which photovoltaic electricity is equal to or cheaper than grid power, can be reached using low cost solar cells. It is achieved first in areas with abundant sun and high costs for electricity such as in California and Japan. Grid parity has been reached in Hawaii and other islands that otherwise use diesel fuel to produce electricity. Speaking at a conference in 2007, General Electric‘s Chief Engineer predicted grid parity without subsidies in sunny parts of the United States by around 2015. Materials presently used for photovoltaic solar cells include monocrystalline silicon, polycrystalline silicon, amorphous silicon, cadmium telluride, and copper indium selenide/sulfide. Thin-film technologies reduce the amount of material required in creating a solar cell. Though this reduces material cost, it may also reduce energy conversion efficiency. Thin-film silicon cells have become popular due to cost, flexibility, lighter weight, and ease of integration, compared to wafer silicon cells. Gallium arsenide multijunction – High-efficiency multijunction cells were originally developed for special applications such as satellites and space exploration, but at present, their use in terrestrial concentrators might be the lowest cost alternative in terms of $/kWh and $/W. GaAs based multijunction devices are the most efficient solar cells to date, reaching a record high of 40.7% efficiency under “500-sun” solar concentration and laboratory conditions.