New approach to measure perovskite-silicon tandem PV module performance via LED-based solar simulators

The Fraunhofer ISE has defined new technical procedures to test the performance of large-area perovskite-silicon tandem PV modules by using the spectral variability of the LED solar simulator. The proposed approach reportedly reduces device handling, time, and consequently financial effort.

Researchers from Germany's Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) have developed a new procedure for the precise and traceable spectral adjustment of LED-based solar simulators for measurements of large-area perovskite-silicon tandem solar modules. 

“We showed, for the first time, how a complete calibration of large-area perovskite on silicon tandem solar cell modules can be carried out by consistently using the spectral variability of LED-based solar simulators,” the research's lead author, David Chojniak, told pv magazine. 

“Carrying out external quantum efficiency (EQE) measurements, power measurements, determination of temperature coefficients, as well as investigations of module performances under variable spectral conditions at a single measurement, the setup provides an enormous potential for the establishment of tandem calibrations with LED-based solar simulators,” he added. 

In the study “Traceable Efficiency Determination of Large-Area Perovskite on Silicon Tandem Modules—Insights From a Calibration Laboratories Perspective,” published in Progress in Photovoltaics, Chojniak and his colleagues explained that the proposed procedure can be carried out on a single measurement setup for full module calibration, while involving full module EQE measurement based on the narrow emission spectra of the different LED types used in the setup.

For their experiments, they used a Wavelabs SINUS-3000 Advanced LED-based solar simulator equipped with 26 spectrally different light sources. It was controlled using the in-house LabVIEW software.

“The distance between the solar simulator and the device under test (DUT) was 7 m,” the paper reads. “The size of the illuminated area was 2.86 m², for which a mean spectral nonuniformity of 0.95% was reached. “The simulator was set up in a temperature-controlled laboratory that was painted in black to reduce reflections.”

The research team also looked into how the limited resolution and accuracy of the LED EQE affect the spectral adjustment of the solar simulator.

The analysis showed that the new procedure offers “good qualitative” agreement with EQE measurements with the LED setup conducted on large-area modules and encapsulated cells at Fraunhofer ISE's CalLab PV Cells.

The academics also adjusted the spectrum of LED-based solar simulators for the measurements of tandem cells and modules in accordance with the IEC60904-1-1 standard. , which describes procedures for the measurement of the current-voltage characteristics of multi-junction photovoltaic devices.

“This procedure for fine-tuning the simulator's spectrum relies on making only minimal changes to its shape, eliminating the need to recalculate spectral mismatch (SMM) factors, and therefore avoids an iterative and time-consuming adjustment process,” the researchers pointed out.

“The proposed procedure considerably reduces device handling, time, and consequently financial effort,” concluded Chojniak.