The Physikalisch-Technische Bundesanstalt (PTB), Germany’s national metrology institute, has modernized its solar module calibration system, achieving a measurement uncertainty of just 0.9%—currently the lowest known uncertainty for a power measurement of silicon solar modules under standard test conditions worldwide.
This achievement was made possible by a new setup based on an LED solar simulator developed by WAVELABS.
“With our new calibration system, we can now accurately measure even large-format solar modules,” explains Dr. Stefan Riechelmann, head of the Solar Module Working Group at PTB.
The optimized light distribution ensures uniform illumination of the entire module with the AM1.5G standard spectrum, which is critical for achieving such low measurement uncertainty.
For PTB, maintaining low measurement uncertainty is a top priority. To ensure this, reference module measurements are regularly made to verify the accuracy of the measuring instruments. Over a monitored period of five months, the standard deviation of the short-circuit current was a mere 0.1%.
The new SINUS-3000 ADVANCED solar simulator can measure the spectral sensitivity of entire solar modules without causing damage, thanks to the precise control of individual LED channels. The simulator is complemented by a climate chamber for stable temperature control. “At PTB, we can dedicate ample time to the comprehensive characterization of the system,” adds Dr. Riechelmann. “This is another key factor enabling us to perform highly
accurate measurements on solar modules.”
Looking ahead, PTB plans to expand its expertise in measuring perovskite and tandem solar modules. The calibration system has been tailored to meet the specific requirements of these advanced technologies. “Accurate measurement of perovskite and tandem modules often requires extended IV measurement times—ranging from minutes to hours,” explains Dr. Riechelmann. “Our LED-based light source also enables flexible spectral adjustments, allowing us to independently control the illumination for the top and bottom cells—an essential prerequisite for precise calibration of perovskite tandem solar modules.”
With this new system, PTB and WAVELABS have set a new standard for solar module measurement, reaffirming PTB’s position as a globally recognized calibration institute for the photovoltaic industry.
