The Dutch energy research institute ECN developed bifacial solar cells with a white layer between and around the cells, which improves their efficiency.

In first tests, the new modules have shown the same maximum power output as a monofacial PV module and compared to bifacial PV modules with a glass back, they have even shown a 5% increase in energy yield.

The problem which is solved with the new approach is that in bifacial modules with a glass back the light that hits the space between the solar cells is lost. In monofacial modules this light can be used because it gets reflected by the white backsheet onto the cells.

ECN researcher Bas van Aken has solved this issue by placing a white mask around and between the cells of a bifacial solar panel. “This white layer reflects light back onto the cells just like the white layer of monofacial solar cells. The advantage of our architecture is that we can still harvest light from both sides as with a regular bifacial solar panel. We combine the advantages of white back sheet reflection with the ones for bifacial light harvesting,” Van Aken explains.

In a standard test, a first white bifacial module with regular solar cells performed better than a regular bifacial module regarding its maximum power output. The front side of the module even showed the same maximum as a monofacial module. Overall, the new white bifacial PV modules showed a 5% better performance than regular bifacial modules and that thus the advantage of white bifacial modules over monofacial modules can be as high as 15 to 35% - depending on the location of the PV system.

“We have proven that white bifacial solar panels can compete with monofacial panels in standard tests and that they show an increase in annual energy yield,” says Van Aken. “The next step is the production of these panels on an industrial scale, followed by large scale tests.”

Tanja Peschel / ECN