Imec develops bifacial n-PERT solar cell

Bifacial n-PERT solar cells have been realised using an industrially-compatible process with a front-side conversion efficiency of 22.8%, according to Imec. Featuring a transparent backside and comparable front- and back contact schemes, bifacial solar cells capture light on both sides of the cell.

As a result, they also profit from indirect light, light reflected by the ground and buildings and diffuse light on overcast days. Tests indicate that, over the course of their lifetime, such cells may generate 10 to 40% more electricity than traditional monofacial cells, depending on their bifaciality, the PV installation properties and the reflection or albedo of the location. This may result in a levelised cost of electricity reduction for PV installations of 10 up to 30%.

“Our Cost-of-ownership calculations indicate that this new cell technology has the potential for a low cost-of-ownership at module level of less than 0.30 $/Wp,” said Filip Duerinckx, principal engineer at imec.

“This results from the low cost patented metallisation, the fine finger contacts, and the potential of multi-wire interconnection schemes. Especially the very limited use of silver compared to traditional screenprinted bifacial cells has a beneficial impact on the cost.

“We are now working to demonstrate this technology on full 60cell modules with wire interconnection.”

Imec’s bifacial n-type PERT cells have nickel-silver plated fingers less than 20µm thick on both the n+ and p+ side of the cell. The cells’ contacts were fabricated in a patented process of simultaneous plating both cell sides.

This cell plating is performed on cassette level without the need for an electrical contact to be made to the substrates. This resulted in a solar cell batch with an average conversion efficiency of 22.4%, with the best cell topping 22.8%.

Peggy Lee