Fraunhofer Center for Silicon Photovoltaics CSP and AESOLAR are co-developing a segmented, patented hot-spot-free (HSF) solar PV module to specifically address the challenges of partial shading and prevent hot spot occurrences.
As the term suggests, a hot spot in a solar module is the overheating of a particular spot in a solar module compared to the rest of the module, attributed mainly to partial shading on the module. This can cause loss of yield by accelerating polymer aging and may lead to module breakdown in extreme cases.
As part of the SegmentPV project, Fraunhofer CSP and AESOLAR claim their patented HSF design reduces hot spot risk by using a segmented module layout and integrated bypass diodes, making it especially well-suited for partially shaded environments.
Fraunhofer CSP is testing the temperature-dependent behavior of the integrated active and passive bypass diodes to identify optimal bypass diodes for various cell technologies that can result in the lowest possible losses and also withstand temperature variations.
It has developed advanced lab tests, including stress, shading, and hot-spot assessments, to assess module reliability and performance. “A novel hot-spot test with alternating operating conditions identifies potential problems during continuous operation, while a special bypass diode test is designed to demonstrate the longevity of the modules, even in a modular system,” explains Fraunhofer CSP.
Based on the simulations offered by the institute, AESOLAR has developed various prototype layouts to segment the module area and developed new module designs. Some of the tests developed are being applied to the prototypes that are delivering ‘positive results’, but need long-term reliability studies. This process should be completed by the end of the project in September 2025.
“With the new HSF module, we can significantly increase the energy yield of photovoltaic systems while simultaneously reducing system costs. This is an important step toward increasing the use of renewable energies in urban areas,” said Fraunhofer CSP Project Manager Matthias Pander.
The institute will share the project results gathered so far at Intersolar Europe 2025 in Munich, Germany, at booth 212 in Hall A2.
Fraunhofer ISE’s Head of Technology, Jochen Rentsch, was recently in India at the TaiyangNews Solar Technology Conference.India 2025, where he discussed the various solar cell technologies, including TOPCon, which was christened by the German institute (see TaiyangNews STC.I 2025 Day 1: Innovation & Strategic Collaborations Key To India’s Solar Manufacturing Success Story).
