US "stacking" method boost for solar power

The new connections developed at North Carolina State University can allow cells to operate at solar concentrations of 70,000 suns worth of energy without losing much voltage as heat.

Stacked solar cells consist of several solar cells that are stacked on top of one another. Stacked cells are currently the most efficient cells on the market, converting up to 45 per cent of the solar energy they absorb into electricity.

But to be effective, solar cell designers need to ensure the connecting junctions between these stacked cells do not absorb any of the solar energy and do not siphon off the voltage the cells produce, effectively wasting that energy as heat.

‘We have discovered that by inserting a very thin film of gallium arsenide into the connecting junction of stacked cells we can virtually eliminate voltage loss without blocking any of the solar energy,’ said Dr. Salah Bedair, a professor of electrical engineering at NC State and senior author of a paper describing the work.