In addition to reducing costs, a key challenge facing PV technologists is to improve the conversion efficiencies of solar cells. The greater the efficiency, the smaller the solar panel needs to be to produce a given output of energy.
Currently, PV efficiencies are pretty low; that’s why a solar system installed on a house rooftop can only supply a modest portion of the home’s electricity requirements. The typical crystalline silicon module in PV systems commonly installed today achieves about 15% efficiency: 15% of the energy from the solar radiation reaching the ground is turned into electricity. The theoretical maximum efficiency for solar is at least 65%, so there’s clearly a lot of room for improvement.
Until now, the best that had ever been achieved in a laboratory had been about 34% efficiency, so the Spectrolab announcement represents a significant leap forward.
When solar systems with efficiencies above 30% and costs below $2/watt can be produced in volume, we’ll be seeing large PV systems in fields and PV modules on most rooftops around the world — and solar can finally begin to fulfill its promise for sustainable energy supply.