Fraunhofer ISE leads a project that develops methods for characterizing perovskite-based tandem modules to facilitate their industrial implementation. A specially built Wavelabs solar simulator is now in use in the institute’s CalLab PV modules.
At the same time, preparations for the industrial production of highly efficient perovskite-silicon tandem solar cells and modules are already underway worldwide. According to Fraunhofer ISE, accurate measurement of tandem solar cells and modules could help pave the way for their industrial implementation.
Accurate measurements are necessary to make objective comparisons between different cells and modules and to make technical improvements. However, unlike traditional silicon PV modules, calibration is significantly more challenging.
Fraunhofer ISE leads a research consortium developing methods to better characterize perovskite-based tandem modules as part of the Katana project, funded by the German Ministry of Economic Affairs and Climate. A solar simulator built especially for this purpose by Wavelabs Solar Metrology Systems is now running on the institute’s CalLab PV modules.
“It is important to provide highly accurate and reproducible measurements for this emerging technology as soon as possible in order to have an objective competition,” said Stefan Glunz, head of Fraunhofer ISE’s Photovoltaic Technology Division.
Martin Schubert, project manager at Fraunhofer ISE, said that all cell layers need to be irradiated with different light sources under conditions that closely mimic sunlight in order to make reliable statements about the efficiency of the entire cell and module.
The new solar simulator makes this possible by measuring lab-scale perovskite silicon PV cells with an area of ​​5 x 5 mm up to 2.40 x 1.30 m PV modules. The simulator’s large wavelength range, which extends from 320 to 1650 nanometers, is due to 28 different spectrally adjustable light channels divided into 40 light sources with a total of 18,400 LEDs. This forms the basis for the testing methods developed by the researchers for the perovskite-silicon tandem technology. The solar simulator also enables the characterization of multijunction solar cells and modules made of other materials.
“The new solar simulator is a milestone towards a standardized calibration procedure for perovskite-silicon tandem modules,” said Falko Griehl, project manager of Wavelabs’ SINUS-3000 Advanced solar simulator. “During its construction, it had to be ensured that the LED lighting homogeneously irradiates the modules over the entire surface and that their light spectra can be adjusted so that all cell layers are realistically activated. With this technique, we can also simulate light in addition to standard spectra at arbitrary times of the day and regions, which makes it possible to analyze this effect on tandem modules.
From 2024, during the characterization of the modules, the heat produced by the longer lighting times will be compensated with a climate chamber, in which the tandem PV cells and modules will be placed for measurement.
The perovskite solar cell manufacturer Oxford PV is a partner in the Katana project.
“The development of a new calibration capability to accurately determine the performance of perovskite silicon cells and modules will enable high-quality independent measurements of this breakthrough technology,” said David Bushnell, Head of Test and Measurement at Oxford PV. “We are delighted to support the wider solar community by helping to fund this project.”
Classic silicon photovoltaic flash simulators, i.e. flashers, cannot be used to characterize perovskite-silicon tandem solar cells and modules, because they cannot regulate the spectrum of light that the tandem cells convert into electricity. In addition, the lighting time of the flashing lights is too short to take into account the effects between sub-cells.
“Due to the metastable behavior of perovskite technology, solar cells and modules must be tested under continuous light,” Fraunhofer ISE added, noting that until now the efficiency of perovskite-based tandem modules had to be measured in complex and weather-dependent outdoor conditions. the tests.
