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Residential photovoltaic systems often experience partial shading from chimneys, trees or other structures, which can induce hot-spots in the modules. If the temperature and frequency of these hot-spots are high, the module's reliability and safety may be at risk. IEC 61215-2:2021 hot-spot endurance test is utilized to evaluate the materials' ability to withstand partial shading. Since modules in residential systems can be subjected to higher temperatures than those in the open field, IEC TS 63126:2020 recommends adjusting the module temperature for the hot-spot endurance test according to the module's operating temperature. This study tested the hot-spot endurance of PERC, IBC and HJT modules under standard (55 °C) and more severe (75 °C, Level 2 condition in IEC TS 63126:2020) test conditions, as well as outdoor accelerated-ageing tests were performed with shadow masks. The results demonstrated that irrespective of environmental conditions, hot-spots can form at lower temperatures, with more shading-tolerant cells (i.e., cells with lower breakdown voltage) or with shorter strings. We also show that it is possible to shorten the effort- and time-consuming hot-spot endurance test described in the standard and obtain similar results. In addition, the hot-spot endurance test for residential PV systems was evaluated in terms of module temperatures and duration. In this respect, we propose to increase the testing temperatures of the hot-spot endurance testing for modules operating at high temperatures in IEC TS 63126:2020.

Technical risks are important criteria to consider when investing in new and existing PV installations. Quantitative knowledge of these risks is one of the key factors for the different stakeholders, such as asset managers, banks or project developers, to make reliable business decisions before and during the operation of their PV assets. Within the IEA PVPS Task 13 Expert Group, we aim to increase the knowledge on methodologies to assess technical risks and mitigation measures in terms of economic impact and effectiveness. The developed outline provides a reproducible and transparent technique to manage the complexity of risk analysis and processing in order to establish a common practice for professional risk assessment. Semi‐quantitative and quantitative methodologies are introduced to assess technical risks in PV power systems and provide examples of common technical risks described and rated in the new created PV failure fact sheets (PVFS). Besides the PVFS based on expert knowledge and expert opinion, an update on the statistics of the PV failure degradation survey is given. With the knowledge acquired and data collected, the risk and cost–benefit analysis is demonstrated in a case study that shows methods for prioritising decisions from an economic perspective and provided important results for risk managing strategies. [ABSTRACT FROM AUTHOR]

An intercomparison of terrestrial photovoltaic (PV) calibrations was performed among a number of European calibration and testing laboratories that participated in the European Metrology Research Program (EMRP) project “PhotoClass”. The purpose of this intercomparison was to evaluate the comparability of calibration and testing services within the stated uncertainties of the individual laboratories. The calibration objects were two world photovoltaic scale (WPVS)-type reference solar cells, one made from crystalline silicon and one made from GaAs. The calibration value (CV) was the short-circuit current under standard test conditions (ISTC). In conclusion, it was found that the CVs are all consistent within the stated uncertainties. This result strengthens the reliance in the calibration chain and in the PV calibration infrastructure in Europe.

Building integrated photovoltaics (BIPV) operate in a unique environment compared with field‐mounted systems and may experience elevated temperatures and recurrent or persistent shading. These stresses are expected to accelerate degradation, but there are few performance reports for true BIPV systems as defined in IEC 63092‐1. Herein, the long‐term performance (over 5–10 years) of 55 BIPV systems in Switzerland is reported. Using a year‐on‐year (YOY) performance loss rate (PLR) analysis, the median degradation rate of all systems together (fleet‐wide) is determined to be 0.06% per year (i.e., essentially no degradation), though there is a large spread of rates. Visual inspection of the systems indicated that some are shaded at times, so a fault detection and diagnosis algorithm (FDDA) is developed to estimate the shading severity of the systems using their daily production profiles. The fraction of time in shading fault presents a linear trend for the upper limit of PLRs, though by itself it is not a strong predictor of system performance. On average, the degree of shading is found to increase in newer systems, and decrease in larger capacity systems. These results highlight the importance of alleviating shading stresses through innovative BIPV module and system design. [ABSTRACT FROM AUTHOR]

Because building-integrated photovoltaic (BIPV) modules are fully integrated into a building envelope, the back of the module can be exposed to little or no ventilation, resulting in increased operating temperatures. As the temperature increases, the performance of the modules decreases, and the durability of the module and its polymeric components (e.g., encapsulant and backsheet) may be impacted. Over the years, three different PV test stands were monitored in Canobbio (southern Switzerland) in different configurations: open-rack, BIPV partially-ventilated and BIPV insulated (non-ventilated) to investigate the effect of the operating temperatures on the long-term energy performance of the different BIPV module types. In this study, the PV modules installed in these test stands were thoroughly examined by: (i) evaluating the long-term performance of the modules, and (ii) establishing a correlation between the electrical performance and changes in the properties of the polymers used in the laminate. In general, we observe that: (i) for some bill of materials (BOM), the higher thermal stress of BIPV configurations can accelerate the degradation, particularly of the encapsulant, leading to current losses attributed to the polymer (discolouration); (ii) in some cases, the higher thermomechanical stress can lead to a higher rate of damaged cells and cell interconnects, resulting in fill factor losses; (iii) on the other hand, a careful selection of the BOM and system design (with adequate rear ventilation) may mitigate the issues related to higher thermal and thermomechanical stresses. [ABSTRACT FROM AUTHOR]