Joshua S. Stein

We present outdoor observations of metal-halide perovskite modules deployed in the Photovoltaic Accelerator for Commercializing Technologies center, which houses one of the world's broadest efforts to test metal-halide perovskite photovoltaic modules outdoors. As of January 2025, outdoor testing has encompassed over 150 modules from 14 different partners. Our findings illustrate how daily changes in efficiency, driven by exposure to light, affect field performance in real-world conditions. These effects cannot be explained by existing outdoor performance models and frustrate the notion of a traditional temperature coefficient.

Field testing, failure analysis, and understanding of degradation mechanisms are essential to advancing metal halide perovskite (MHP) photovoltaic (PV) technology toward commercialization. Here, we present performance data from up to 1 year of outdoor testing of MHP modules in Golden, Colorado. The module encapsulation architecture and encapsulant materials have a significant impact on module reliability, with modules containing a polyolefin elastomer (POE) in addition to a desiccated polyisobutylene (PIB) edge seal outlasting modules with only a PIB edge seal or PIB blanket. Nondestructive and destructive characterization of the field‐tested modules points to module scribes and interfaces as areas of potential mechanical weakness and chemical migration, resulting in shunt pathways and increased series resistance. Finally, indoor accelerated stress testing with light and elevated temperatures is performed, demonstrating failure with similar scribe degradation signatures as compared to the field‐tested modules. Under both outdoor testing and light and elevated temperature conditions, electrochemical corrosion between the copper electrode and the mobile iodine ions appeared dominant, with a significant progression at the scribes that is speculated to result from an interplay between the initial laser damage and joule heating from enhanced ion diffusion under bias.

Understanding the impact of variation in the solar spectrum on photovoltaic (PV) device output is critical for accurate and reliable PV performance modeling. While previous studies have examined these spectral effects extensively at the module level, this study examines the spectral impact at the cell level and how subsequent current mismatch can influence module-level output. Cell-level external quantum efficiency (EQE) data from 11 new commercial PV modules are analyzed. The module power output, as determined by the spectral mismatch factor of the module-limiting cell, is computed using the measured cell EQE data in conjunction with gridded meteorological and spectral irradiance data simulated at an approximately 20 $\mathbf{\mathrm{km}}$ resolution across the contiguous USA over one year. This study finds only a small variation in annualized module output of around 0.2% as a result of intramodule EQE variation. However, these losses exhibit significant seasonality, varying by up to around four times the annualized energy difference on a month-to-month basis. The seasonality of the energy loss has implications for subannual PV performance analysis applications such as capacity testing.

The performance of photovoltaic (PV) modules is determined by the interplay between their inherent characteristics and the prevailing weather conditions. Although the impacts of different characteristics (e.g., low-light behavior, spectral mismatch, temperature coefficient, etc) are known, they have not been quantified over large geographic regions. This study uses the Climate Specific Energy Rating (CSER) and specific yield metrics as criteria to determine how different PV modules perform across climates in the contiguous United States (CONUS) and identifies the underlying drivers behind the observed variations. The annual CSER and specific yield of various PV technologies vary by more than 10% and 30%, respectively, across the CONUS. As expected, temperature has the most significant impact on CSER, affecting CSER by up to 13.1%, while spectral effects account for up to 4.9% variation in the case of cadmium telluride modules. Additionally, minor differences in parameter estimation procedures are shown to result in CSER differences of up to 1.5% in some climates. Furthermore, the IEC 61853-4 reference climatic datasets are found to overestimate CSER by 2–4% relative to climatic data for locations of actual PV systems in the United States. A new set of reference locations that accurately represents CSER across CONUS is proposed as an alternative to the IEC 61853-4 reference datasets.