PV Lifetime Project - 2024 NREL Annual Report

DOE's PV Lifetime project was initiated in 2016 with the goal of accurately characterizing the early-life evolution of photovoltaic (PV) field performance. Different PV cell and module technologies result in different initial degradation rates due to effects like light-induced degradation (LID) and light & elevated temperature-induced degradation (LeTID). To accurately characterize the initial field degradation of maximum power (Pmp) requires the use of high-accuracy indoor IV curve measurements at standard test conditions. Therefore, PV modules involved in this study are removed from the field once or twice per year and brought indoors for measurement under constant temperature and irradiance conditions. Current samples deployed and monitored in this way include Jinko Solar (2016), Trina Solar (2016), Hanwha Q-Cells (2017), Panasonic (2018), LG (2018), Canadian Solar (2018), Mission Solar (2019). Modules from Sunpreme (2019), and LONGi (2020) have been deployed and were first reported on in the 2022 report. For this report, initial baseline measurements for two additional partners are included: REC (2023) and Solaria (2023). Overall annual degradation rates are as follows: our first modules to be deployed (Jinko and Trina) have annual median degradation rate between -0.35%/yr and -0.55%/yr, mainly concentrated in the first year. The QCells mono-PERC and multi-PERC modules have an annual degradation rate of -0.4%/yr and -0.3%/yr respectively, also concentrated in the first year of operation. Mission Solar, LG and LONGi modules are all displaying modest degradation, better than -0.25% / year. Indeed, Mission Solar fielded modules degraded less than their control modules which remain indoors and un-exposed. By comparison, the Sunpreme n-HIT bifacial modules are showing a rapid loss rate around -2%/yr, or almost -8% total to date. This is largely attributed to loss in front-side Isc, and this rapid loss has been corroborated by comparing against RdTools degradation analysis, using real-time field performance data. Several module types exhibit strong seasonal performance change, consistent with LeTID susceptibility. This is characterized by lower indoor IV measurement after prolonged high-temperature exposure, and a recovery during cooler temperatures. This can result in a sawtooth-type response when sequential indoor measurements are taken in the spring and again in the fall. These types of profiles are visible in Jinko, Trina and Mission Solar module types. It is possible that Canadian Solar multi-PERC also follows this trend, but the measurement timing has not lined up to confirm this possibility. An analysis was conducted on the initial module performance relative to their nameplate rating. Most module types had initial performance right at nameplate rating, or within 1%: Jinko, Trina, LONGi, Panasonic, QCells and REC N-peak (TOPCon). Other module types came in 2% - 3% below nameplate: Mission Solar, Solaria and REC 400 Pure Alpha. LG was actually measured at 2% above nameplate, and the Sunpreme heterojunction modules had inconsistent measurements which made it difficult to make any statements on their nameplate accuracy. Three related publications published in 2022 have made use of the PV Lifetime data included in this report, and can help provide greater context and additional information. M. Theristis et al., "Onymous early-life performance degradation analysis of recent photovoltaic module technologies" (http://doi.org/10.1002/pip.3615) provides additional analysis and measurements from New Mexico and Florida test sites for comparable module samples. An international round-robin test on LeTID stabilization processes was published by Karas et al., "Results from an international interlaboratory study on light- and elevated temperature-induced degradation in solar modules" (DOI: 10.1002/pip.3573). Finally, a detailed discussion of LeTID kinetics and how this affects field performance and LCOE is provided in the MRS Bulletin, I. Repins et al., "Long-Term Impact of Light and Elevated Temperature Induced Degradation on Photovoltaic Arrays". (DOI: 10.1557/s43577-022-00438-8)