Forty years and 152 world records in, Fraunhofer ISE's calibration laboratory, CalLab, has been solar's independent scorekeeper since 1986. Five years later, in 1991, the lab widened its brief to PV modules, and the first confirmed record followed in 1992: a mini silicon solar module rated at 16.4 percent efficiency, submitted by Deutsche Aerospace using Bayer silicon wafers. The most recent is a module from AZUR SPACE, temicon and Fraunhofer ISE itself, which reached 34.4 percent – unthinkably high by 1991 standards, and currently the world's most efficient solar module.
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Of the 152 records, 66 were for PV modules, mostly silicon, and 86 for solar cells. "In the laboratory's early days a small silicon PV module with an efficiency of 16.4 percent could set a record," says Martin Kaiser, head of CalLab PV Modules. "Today's large-area silicon PV modules are already close to the physically possible limit." The most recent silicon record specifically, as opposed to the multi-material record above, originated from LONGi in 2025, at 26.2 percent.
Beyond silicon's limit
As silicon approaches its ceiling, research groups are turning to tandem and multi-junction cells, stacking subcells made of different semiconductor materials to push past. A growing number of these new approaches have passed through CalLab's doors in recent years. The world's most efficient solar cell overall is a quadruple-junction device combining a tongue-twisting stack of materials: gallium-indium phosphide, aluminium-gallium arsenide, gallium-indium arsenide phosphide and gallium-indium arsenide, which reached 47.6 percent and was confirmed by CalLab in 2022.
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"Our goal is to accompany every photovoltaic development with reliable measurements," says Dr. Jochen Hohl-Ebinger, head of CalLab PV Cells. "We are constantly refining our measurement technology, often in close collaboration with measurement equipment manufacturers, and working with others on standardised measurement methods for new cell and module types within standards committees." That work has recently focused on perovskite-silicon tandem cells and modules, for which CalLab PV Modules now uses a new multispectral solar simulator.
Why independent measurement matters
"Independent calibration laboratories that are respected by all industry stakeholders worldwide are essential for the photovoltaic industry," said Prof. Dr. Andreas Bett, Fraunhofer ISE's director. "Impartial and transparently traceable performance measurements enable fair competition. Ultimately, all stakeholders benefit from this." The figures are drawn from an analysis of the Solar Cell Efficiency Tables, spanning versions 1 to 68 and covering CalLab's 40-year history, from its first tests in 1986 to today. Here's to the next 40 years, and whatever record comes next. (TF)
