Insolight, a Swiss startup, has taken a different tack – embedding a grid of hexagonal lenses in a solar panel’s protective glass, thus concentrating light 200 times.
To follow the sun’s motion, the cell array shifts horizontally by a few millimetres throughout the day. It is a bid to make concentrated solar cheap.
“The architecture of these conventional concentrated photovoltaics is very costly. What we’ve done is miniaturise the sun tracking mechanism and integrate it within the module,” says Insolight’s chief business officer David Schuppisser.
“We’ve done it in a cheaper way [that] you can deploy anywhere you can deploy a conventional solar panel,” he says.
The Universidad Politécnica de Madrid’s solar energy institute measured Insolight’s current model as having an efficiency of 29%. It is now working on a module that is hoped to reach 32% efficiency.
Current silicon technology is not quite dead, though, and there are approaches to make tiny, quick wins in efficiency. One is to add an extra layer to a cell’s back to reflect unabsorbed light back through it a second time. This improves efficiency by 1-2%.
Another is to add an outside layer, which lessens losses that occur where silicon touches the metal contacts. It’s only a “small tweak”, says Xiaojing Sun, a solar analyst Wood Mackenzie research – adding 0.5-1% in efficiency – but she says these changes mean manufacturers only need to make small alterations to their production lines.
From such small gains – to the use of concentrated solar and perovskites – solar tech is in a race to raise efficiency and push down costs.
“Spanning this magical number 30%, this is where the solar cell industry could really make a very big difference,” says Swift Solar’s Max Hoerantner.