A simple reordering of the layers in solar-cell modules can help improve efficiency.

A solar-cell module that mitigates cell-to-module losses has been developed by KAUST researchers following a rethink of the module’s optical design and how it should be stacked.

Research laboratories around the world are working to constantly improve the efficiency of solar cells. But using these devices in the real world represents an extra challenge. For example, solar cells need to be incorporated into modules that can protect the sensitive materials from harsh environments. These modules can reduce the power conversion efficiency, thus losing the performance gains so diligently won in the laboratory.

Lujia Xu, Stefaan De Wolf and their KAUST colleagues have constructed a more efficient solar-cell module with an enhanced optical design. The solar cells used by the team were made of a combination of two light-absorbing semiconductors: one silicon and the other made from a perovskite material. Silicon is now a well-established material in solar cell manufacture. And while perovskites are an emerging material, adding a thin layer on top of the silicon has already been shown to improve performance with an acceptable increase in cost.

These so-called perovskite–silicon tandem solar cells have previously exhibited efficiencies in optical-to-electrical power conversion as high as 30 percent. And theoretical modeling has indicated it could go as high as 45 percent. But when the KAUST team put their tandem solar cells into a module, they found that the efficiency dropped from 28.9 percent to 25.7 percent. Their module was made by sandwiching the solar cells between two glass sheets, with the inside filled with thermoplastic polyurethane to encapsulate the solar cells.