Swiss researchers have done the (theoretically) impossible, creating not one but two silicon-based solar cells with efficiencies greater than 30% — breaking a world record and potentially illuminating the path to a future of cheaper clean energy.

The status quo: Solar cells absorb light and convert it into electricity. They’re the basis of most solar power tech, and about 95% of them are made from silicon because it’s abundant, long-lasting, and relatively cheap.

Most of the silicon solar cells sold today are about 22% efficient, meaning they convert 22% of the solar energy that hits them into electricity. We don’t have too much room for improvement with silicon solar cells, either, as they have a theoretical efficiency limit of about 29%.

The compact row houses feature carefully angled solar panels that harness every moment of the sun.

A new solar panel design can efficiently convert light into electricity, while still allowing almost 80% of incoming light to pass through.

Perovskites, mineral materials composed of calcium titanate, have been found to be valuable for the fabrication of high-performance solar cells. While teams of scientists and engineers worldwide have been developing and testing perovskite solar cells in laboratory settings, large-scale outdoor evaluations of these cells are still lacking.

Researchers at University of Rome Tor Vergata, the Hellenic Mediterranean University in Crete, BeDimensional S.p. A., Great Cell, the Italian Institute of Technology (IIT) and University of Siena have recently manufactured large-area perovskite solar panels engineered using two-dimensional (2D) materials. They then successfully integrated 9 of these solar panels into a stand-alone solar farm, located on the Greek island of Crete. This team’s findings, presented in a paper published in Nature Energy, could facilitate and inform the future large-scale implementation of perovskite solar cells.

“Our recent paper highlights our joint research efforts for the last 5 years in the upscaling of perovskite PVs, starting from lab cells to modules, panels and finally to a solar farm infrastructure,” Francesco Bonaccorso, one of the researchers who carried out the study, told to Tech Xplore. “This project was specifically developed in the context of the European Graphene Flagship initiative, which established a close collaboration between University Tor Vergata, BeDimensional S.p. A., GreatCell and Hellenic Mediterranean University, having both complementary and widely different skillsets.”

Inserting a metal fluoride layer in multilayered perovskite-silicon tandem solar cells can stall charge recombination and enhance performance, KAUST researchers have found.

Tandem solar cells that combine perovskite and silicon-based subcells in one device are expected to better capture and convert sunlight into electricity than their conventional single-junction silicon analogs at a lower cost. However, when sunlight strikes the perovskite subcell, the resulting pairs of electrons and positively charged holes tend to recombine at the interface between perovskite and the electron-transport layer. Also, a mismatch between energy levels at this interface hinders electron separation within the cell. Cumulatively, these problems lower the maximum operating voltage available, or open-circuit voltage, of the tandem cells and limit device performance.

These performance issues can partially be solved by introducing a lithium fluoride layer between the perovskite and electron-transport layer, which usually comprises the electron-acceptor fullerene (C₆₀). However, lithium salts readily liquify and diffuse through surfaces, which makes the devices unstable. “None of the devices have passed the standard test protocols of the International Electrotechnical Commission, prompting us to create an alternative,” says lead author Jiang Liu, a postdoc in Stefaan De Wolf’s group.

The power plant can produce 4.2 million units of power every year.