28.7% Efficiency For 2-T Tandem Solar Cell

• HZB and Hanwha Q Cells have reported achieving 28.7% efficiency for a 2T tandem solar cell
• They used HZB developed perovskite as the top cell, combining it with silicon bottom cell based on Q Cells' Q.ANTUM technology
• The team says this is an improvement of 1% percentage point over 27.8% efficiency they reported in 2020

German solar research center Helmholtz-Zentrum Berlin (HZB) and Hanwha Q Cells have announced 'world record' efficiency of 28.7% for a 2-terminal (2T) tandem solar cell bringing together a perovskite top cell, and a mass-production ready silicon bottom cell based on the latter's Q.ANTUM technology.

They believe the efficiency improvement is important since it was reached using an 'industry feasible' and cost-efficient bottom cell structure based on the Q-ANTUM technology.

Working on the project for past 3 years, the efficiency improvement was achieved by the team thanks to the improvement of both the perovskite and the silicon sub cells. No other details were shared.

"It is remarkable how close the jointly achieved efficiency with a mass production ready bottom cell already comes to what we can reach at a lab scale," said HZB Scientific Director Prof. Dr. Bernd Rech. This, the team claims, is an improvement of almost 1 percentage point compared with the 27.8% efficiency achieved in 2020 for the same configuration.

HZB Group Leader and Junior Professor at Technische Universität Berlin, Prof. Dr. Steve Albrecht added, "It is highly exciting that we enable this high tandem efficiency utilizing industry relevant bottom cells with a high market share, so there might be fast impact of the tandem technology to revolutionize the PV market."

As a solar technology company, Q Cells is investing heavily in research and development (R&D) which in Germany is aimed at being expanded to €125 million over the next 3 years out of which it plans to commit a 'sizeable' portion for the commercialization of perovskite-silicon tandem technology.

In December 2021, Q Cells pledged an additional €15.5 million for its German R&D headquarters for solar module technology development, on top of €20 million into requisite equipment for next generation PV technology development it pledged in 2020 (see Hanwha To Launch New N-Type Solar Module In 2021).

Recently, HZB and ISH reported 21.3% efficiency for a tandem perovskite and PERC silicon cell with potential to go up to 29.5% (see PERC Based Tandem Solar Cell).