Question: what properties make a material suitable for use as the active layer in a solar cell

title: Solar cell
text: Solar - specific feed - in tariffs vary by country and within countries . Such tariffs encourage the development of solar power projects . Widespread grid parity , the point at which photovoltaic electricity is equal to or cheaper than grid power without subsidies , likely requires advances on all three fronts . Proponents of solar hope to achieve grid parity first in areas with abundant sun and high electricity costs such as in California and Japan . In 2007 BP claimed grid parity for Hawaii and other islands that otherwise use diesel fuel to produce electricity . George W. Bush set 2015 as the date for grid parity in the US . The Photovoltaic Association reported in 2012 that Australia had reached grid parity ( ignoring feed in tariffs ) .