Yoha Solar has completed factory inspection of a perovskite/silicon tandem module electroluminescence (EL) tester and packed the system for shipment to a research institute in Shandong, China. The equipment will support the institute’s research on tandem cells, with a particular focus on layer-resolved imaging and localization of internal defects in tandem modules. The unit departed from Wuhan via dedicated logistics services. After delivery, Yoha Solar engineers will carry out on-site positioning, installation, and commissioning.
Perovskite/silicon tandem technology is one of the most closely watched routes toward higher photovoltaic efficiency, with laboratory-scale cell efficiencies already exceeding 33%. However, the stacked structure also creates a challenge for defect inspection. Because the top and bottom cells are integrated into one device, conventional EL images can contain signals from both layers, making it difficult to determine whether a dark area originates in the perovskite layer or the silicon layer. For researchers, identifying the source of a defect is essential to subsequent failure-mechanism analysis and to drawing reliable conclusions in academic publications.
The tester addresses this challenge through dual-spectrum, layer-resolved imaging. It is equipped with two customized industrial cameras, each configured to independently capture the emission band of either the perovskite top cell or the silicon bottom cell. The two images are acquired and stored separately, helping researchers identify which layer contains defects such as microcracks, broken fingers, poor solder joints, pinholes, interfacial delamination, and localized degradation. With a camera resolution of 20 megapixels, the system can capture fine defects associated with cracks narrower than 0.03 mm. This capability is particularly useful for research teams investigating the early stages of degradation at tandem-cell interfaces.
University laboratories have different testing needs from mass-production lines. Sample dimensions can vary frequently, from half-cut cells one day to small prototype modules the next. The tester provides an effective testing area covering lengths from 250 to 900 mm and widths from 250 to 700 mm, accommodating samples of different sizes. Its programmable DC power supply supports 0–200 V and 0–20 A, meeting the high-voltage injection requirements of tandem-cell testing. The fully enclosed dark chamber eliminates the need to construct a separate darkroom, allowing the system to operate in a standard laboratory environment. Image acquisition time is adjustable from 100 to 700 ms, making it practical to capture images of hundreds of samples in a day.
8
In addition to tandem modules, the system supports conventional crystalline-silicon cell technologies, including PERC, TOPCon, and HJT, as well as single-junction perovskite cells. This flexibility allows a laboratory to use one system for multiple research tasks and make more efficient use of its equipment budget. The software supports barcode scanning, categorized storage of test results, and double-click image magnification for inspecting fine features. These functions help students document experiments, enable supervisors to trace historical data, and allow research teams to export image materials for academic papers.
This shipment marks another delivery by Yoha Solar to a research institute for perovskite-related testing. From steady-state LED solar simulators to integrated EL/PL testers and dedicated EL systems for tandem modules, Yoha Solar continues to develop its inspection equipment portfolio in response to the practical needs of both academic research and the photovoltaic industry. After the system arrives in Shandong, Yoha Solar engineers will provide on-site installation, commissioning, and operator training so that the research team can begin collecting data as soon as possible. The equipment will also provide an important inspection tool for future reliability studies of tandem modules.