Bending light to our will

Solar energy is currently enjoying substantial growth and investment, owing to worldwide sensitivity to energy security and climate change. Solar energy is an inexhaustible resource and is in abundant supply on all continents of the world. The power density of sunlight (similar to 1000 W/m(2)) and the efficiency of photovoltaic devices (similar to 10-25%) are high enough so that land use does not limit photovoltaic deployment at the terawatt scale. However solar photovoltaics are currently too expensive to achieve parity with other forms of electricity generation based on fossil fuels. This is largely due to the cost (and for some cases, the abundance) of materials used in photovoltaic modules and systems, and the cost of deploying in current form. This economic and social context has created the present situation where there is widespread interest in photovoltaic technology for power generation, but the cumulative installed world capacity for photovoltaics is <50 GW, and it appears to be very challenging for photovoltaics to play a very substantial role in large-scale (terawatt) electricity generation in the short term.