"Katana" project to establish reliable measuring system for tandem solar cells

• To pave the way for the industrial application of reliable perovskite-silicon PV modules, a reliable measuring system for tandem solar cells and also modules have to be established. Just after that can objective comparisons in between various cells and modules occur. In comparison to conventional silicon PV modules, nevertheless, the calibration is considerably more challenging.

A project consortium, led by the Fraunhofer Institute for Solar Energy Systems ISE, is consequently establishing methods for defining perovskite-based tandem modules in the "Katana" project, funded by the German Federal Ministry for Economic Affairs as well as Climate BMWK. The solar simulator specially developed for this function by the company Wavelabs Solar Metrology Systems GmbH is currently being used in the CalLab PV Modules of the study institute.

" It is necessary to provide extremely accurate and also reproducible measurements for this emerging technology asap so that there can be objective competition," states Prof. Dr. Stefan Glunz, Division Director for Photovoltaic Technologies at Fraunhofer ISE.

To be able to determine perovskite tandem modules, a detailed understanding of the contained solar cells is called for. Dr. Martin Schubert, project head at Fraunhofer ISE, clarifies: "All cell layers must be irradiated by different source of lights under conditions that copy - as specific as possible - those under in sunlight in order to make reliable declarations concerning the effectiveness of the entire cell and also module.

The new solar simulator in the CalLab PV Modules of Fraunhofer ISE, which has actually been finished for calibration, currently makes this possible: It gauges lab-scale perovskite-silicon PV cells with a location of 5 by 5 millimeters approximately PV modules of 2.40 by 1.30 meters. The very large wavelength variety of the simulator, ranging from 320 to 1650 nanometers results from 28 various spectrally adjustable light channels distributed over 40 lights with a total amount of 18,400 LEDs. This forms the basis for the test treatments developed by the researchers for perovskite-silicon tandem modern technology. The solar simulator also enables the characterization of multi-junction solar cells as well as modules constructed from other products.

" The new solar simulator is a landmark towards a standard calibration treatment for perovskite-silicon tandem modules. Throughout its building, we needed to make certain that the LED illumination homogeneously irradiates the modules over the whole surface area which their light ranges can be changed to ensure that all cell layers are realistically activated," claims Falko Griehl, project supervisor for the SINUS-3000 Advanced solar simulator at Wavelabs. "With this technology, past the basic spectra, we can additionally mimic light at approximate times of day as well as regions, which allows this influence on tandem modules to be evaluated." From 2024, the warmth created by the longer lighting times throughout module characterization will be compensated by a climate chamber, in which the tandem PV cells and modules will certainly be placed for measurement.

Perovskite solar cell pioneer as well as maker Oxford PV is an associate companion in the Katana project. Dr. David Bushnell, Oxford PV's Test and also Measurement Department Manager, claimed: "The development of a new calibration capability for properly figuring out the efficiency of perovskite-on-silicon cells and also modules will certainly allow high-quality independent measurements of this innovation innovation. We are pleased to be supporting the larger PV community by assisting to fund this project."

For the characterization of perovskite-silicon tandem solar cells as well as modules, the classic flash simulators, or flasher, from silicon photovoltaics are not excellent for usage, as flashers can not variably readjust the light range that the tandem cells convert into power. Moreover, the illumination time by a flasher is too short to make up the impacts in between the sub-cells. For the metastable actions of perovskite modern technology, the solar cells and also modules must be tested under constant light. Previously, the performance of perovskite-based tandem modules needed to be measured in facility as well as weather-dependent outdoor tests.