Current and future photovoltaics

Abstract

Photovoltaics, now a billion-dollar industry, is experiencing staggering growth as increased concerns over fuel supply and carbon emissions have encouraged governments and environmentalists to become increasingly prepared to offset the extra cost of solar energy. Three 'generations' of photovoltaics have been envisaged that will take solar power into the mainstream. Photovoltaic production is currently 90% 'first-generation' or '1G' solar cells that rely on expensive bulk multi-crystalline or single-crystal semiconductors. Dominated by silicon wafers, they are reliable and durable but expensive. Half of the cost of 1G devices is the silicon wafer and efficiencies are limited to around 20%. Instead of using wafers, cheaper 'second-generation' (2G) solar cells would use cheap semiconductor thin-films deposited on low-cost substrates to produce devices of similar efficiencies. A number of thin-film device technologies account for around 5–6% of the market. As 2G technology reduces the active material cost, eventually the substrate will be the cost limit, and higher efficiency will be needed to maintain the $/W cost-reduction trend. 'Third-generation' devices (3G) will utilise new technologies to produce high-efficiency devices. Recently, tremendous advances outside the photovoltaic industry in nanotechnologies, photonics, optical metamaterials, plasmonics and semiconducting polymer sciences offer the prospect of cost-competitive photovoltaics based on new science and 3G concepts. Within the next 20 years, it is reasonable to expect that cost reductions, a move to 2G technologies and the implementation of some new technologies and 3G concepts can lead to fully cost-competitive solar energy