Fraunhofer ISE’s CalLab measurements show that solar PV modules often fell short of the power specifications provided by manufacturers
The discrepancy peaked between 2020 and 2023 with an average power shortfall of about 1.3%
A slight turnaround is seen since 2024 suggesting that manufacturers are becoming aware of the issue and working on it
German solar energy institute Fraunhofer Institute for Solar Energy Systems ISE says there is a growing discrepancy between the performance data offered by solar module manufacturers and their measurement results in the lab.
It says this based on more than 70,000 power measurements on PV modules carried out by the institute at its calibration laboratory CalLab since 2012, as it analyzed 1,043 of the collected performance measurements taken from monocrystalline silicon PV modules under standardized conditions.
It indicates that from 2012 to 2016, deviations were generally minimal, staying within an average difference of less than 1%, pointing to consistent and reliable performance. There was a 0.6% average deviation in 2016.
However, from 2017 to 2023, the data has shown a negative trend. For the year 2023, the negative deviation between the manufacturer’s specification and the CalLab results showed an average power reduction of 1.3%. “A positive deviation was hardly ever observed,” shared Fraunhofer ISE Head of the Department Module Characterization and Reliability, Daniel Phillip.
Nonetheless, there has been a slight turnaround since 2024, which could be because the manufacturers are now aware of this, but still showing strong negative deviations of 1.2% on average.
“If we assume that our data is representative of the German installation market, an average underperformance of 1.2 percent with an additional 16.2 gigawatts in 2024 corresponds to a total output of around 195 megawatts,” added Phillip.
Fraunhofer ISE filtered the data by removing inconsistent data and excluding statistical distortions. It studied only the top 10 module manufacturers in the respective year.
“The findings also make it clear how important a reliable, continuous and independent infrastructure is for the quality control of PV modules,” said Institute Director at Fraunhofer ISE, Prof. Andreas Bett, “especially when the German and European PV markets are over 90 percent dependent on imports of PV components.”
Fraunhofer ISE’s Head of Technology Jochen Rentsch will be at TaiyangNews Solar Technology Conference India 2025 on April 10 and 11 in New Delhi, India to talk about the status and outlook of solar cell and module technologies. He will join several other technologists and scientists who are helping create a resilient solar manufacturing industry in India. Early bird registrations are currently on here.