The ‘dark side’ of solar power can now be unlocked after breakthrough

19 Dec 2019

Image: © dieterjaeschkephotos/

Researchers have found a way to harvest power from the dark underside of solar panels thanks to a new formula.

The efficiency of solar panels is set to be boosted significantly with the harnessing of a powerful new formula. Most solar panels today capture sunlight and convert it to electricity, but only from the side that’s facing the sun.

While double-sided solar cells that can sit vertically on land or rooftops are out there, it hasn’t been known exactly how much electricity these panels could ultimately generate or the money they could save.

Now, researchers from Purdue University have revealed a new thermodynamic formula that shows bifacial cells making up double-sided panels generate on average up to 20pc more sunlight to electricity than traditional monofacial cells. It’s estimated that bifacial solar cells will account for nearly half of the global marketshare by 2030.

In a paper published to the Proceedings of the National Academy of Sciences, they said the new formula can calculate in minutes the most electricity that bifacial solar cells could generate in a variety of environments.

‘The absolute gain is significant’

“It took almost 50 years for monofacial cells to show up in the field in a cost-effective way,” said researcher Muhammad ‘Ashraful’ Alam.

“The technology has been remarkably successful, but we know now that we can’t significantly increase their efficiency anymore or reduce the cost. Our formula will guide and accelerate the development of bifacial technology on a faster time scale.”

Using the formula, the researchers can recommend better double-sided solar cells design for panels on farmlands and the windows of buildings in densely populated areas. For example, transparent bifacial panels can generate power on farmland without casting shadows that would block crop production.

The paper also recommends ways to maximise the potential of bifacial cells by manipulating the number of boundaries between semiconductor materials, called junctions, that facilitate the flow of electricity.

Co-author Mohammad Ryyan Khan said: “The relative gain is small, but the absolute gain is significant. You lose the initial relative benefit as you increase the number of junctions, but the absolute gain continues to rise.”

Colm Gorey was a senior journalist with Silicon Republic