Photovoltaic Thermal Runaway Test Capability for Advanced Space Solar Cells

Next-generation space solar cell technologies, including inverted metamorphic multijunction (IMM), ultra-thin silicon, and perovskite-based cells, offer significant improvements in power density, efficiency, and mass reduction. However, many of these advancements increase susceptibility to photovoltaic thermal runaway (PTR), a failure mechanism triggered by localized heating under high current density, shadowing, or poor thermal dissipation. PTR represents a growing risk to space missions, threatening both commercial and government platforms that rely on evolving photovoltaic technologies to meet expanding power demands. This proposal seeks to address that risk by developing a compact, modular, and low-cost environmental test chamber capable of evaluating solar cells under all known conditions that may lead to PTR. The proposed hardware will allow research institutions, manufacturers, and government test labs to determine PTR onset thresholds and evaluate mitigation strategies in a controlled and replicable laboratory setting. The system will support testing under:- Vacuum conditions, including eclipse exit simulations- Tunable irradiance, including partial shading and >1 sun intensity- Wide temperature range, from –90?°C to +140?°C, with optional LN? cooling for deeper cryogenic tests- Electrical biasing, including operation near open-circuit voltage (Voc)- Optional laser induction, for localized heating studies Key diagnostic capabilities include infrared imaging, electroluminescence quenching detection, and continuous electrical monitoring, enabling researchers to induce, confirm, and quantify PTR events under a wide range of operating scenarios.The chamber’s modular wall design will allow future adaptation for more advanced configurations, such as beamline integration or radiation testing. While the prototype targets single-cell testing, the architecture is designed for straightforward scaling to coupon- and module-level systems. The development plan includes two generations of two prototypes—each generation is used for internal testing and delivered to the government—followed by refinement and commercialization to support broader adoption. This work is directly aligned with draft guidance from the space photovoltaic technical community. As the AIAA committee notes in language that has been approved to be added to the S111a standard:      “Concurrent changes to the packaging system, along with use of new photovoltaic device technology, may warrant the need for bench-top and/or laboratory testing to artificially induce a hot spot and assess the system capability to avoid PTR.” This proposal delivers exactly such a test solution—fast, flexible, and extensible thermal bench and solar exposure in vacuum capabilities—to accelerate understanding of PTR, support resilient solar array development, and de-risk next-generation photovoltaic technologies for spaceflight.