Solar power to be mainstream energy source by 2025

Photovoltaics, now a billion dollar industry, is experiencing staggering growth as concerns over fuel supplies and carbon emissions have encouraged environmentalists and governments to subsidise the cost of solar energy.

As a form of energy, solar power is currently at least four times too expensive and it will only become truly mainstream when its dollar to Watt ratio is comparable to other energy sources.

The timing will depend on levels of research investment, of national, international and multi-national co-operation and the rate of increase in the cost of non-renewable energy. However, it seems inevitable that by 2025 photovoltaics will be a fully cost competitive alternative to gas, coal, nuclear or any other renewable supply.

Photovoltaic production is currently based on “first generation” solar cells that rely upon expensive bulk multi-crystalline or single crystal semiconductors. Although, these structures are reliable, half the cost of current devices is as a result of the use of silicon wafers.

As half the cost of "first generation" photovoltaics is that of the 200-250 micron thick silicon wafer, a cheaper "second generation" of solar cells could use cheap silicon thin-films deposited onto glass.

Then "third generation" devices could use new technologies to produce high-efficiency devices. The prospects for advances in the manufacture of high efficiency devices have been boosted in recent years by tremendous advances outside the photovoltaics industry. Nanotechnologies, photonics, optical metamaterials, plasmonics and semiconductor polymer sciences all offer the prospect of cost-effective new technologies that can be applied to photovoltaics.

Within the next 20 years, it is very reasonable to expect that cost reductions, a move to second generation silicon technologies and implementation of some new technologies will lead to truly cost-competitive solar energy.’

by Dr Darren Bagnall, from the University of Southampton’s School of Electronics & Computer Science

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