• Energy Research

Long-term photovoltaic (PV) module reliability is highly determined by the durability of the polymeric components (backsheet and encapsulation materials). This paper presents the result of experiments on encapsulant degradation influenced by the backsheet permeation properties. Towards this goal, one type of ethylene/vinyl acetate copolymer (EVA) was aged in glass/EVA/backsheet laminates in accelerated aging tests (up to 4000 h for Damp-Heat (DH) and up to 480 kWh/m2 for UV and UV-DH combined). The samples contained three backsheets with different permeation properties to examine their impact on EVA degradation. Thermal and chemical characterization shows that the EVA degradation is stronger with the glass–EVA–polyamide (PA)-based backsheet than with the polyethylene terephthalate (PET)-based backsheets. The higher oxygen transmission rate (OTR) of the PA-based backsheet may increase photo-oxidation and aggravating the degradation of EVA in the laminates. Furthermore, FTIR results were used to demonstrate the effect of damp heat exposure on the EVA interfaces, showing an accelerated degradation at the glass–EVA interface. The comparison of accelerated aging stress factors reveals that EVA suffers the strongest chemical and optical degradation when high UV, high temperature and high relative humidity are combined simultaneously.

We demonstrate a new hybrid morphology that facilitates charge transport and charge separation at the interface between the nanocarbon and the semiconductor and so greatly improves their performance in environmental and sustainable energy applications.

The study investigates the stabilization behavior of Tunnel Oxide Passivated Contact (TOPCon) photovoltaic (PV) cell technology following UV-induced degradation (UVID). It focuses on the after-effects of lab-induced UVID, particularly the drastic effects of power loss during dark storage after UV irradiation. To counteract these effects, which are considered as artifacts that do not affect the expected outdoor performance, the paper presents light soaking at 25 °C module temperature as reproducible stabilization procedure for module performance measurements. Considering the increasing market presence of TOPCon-based PV modules and recent reports of, in some cases tremendous extent, UVID in the lab, stabilization after UVID is highly relevant. The study further explores the development of degradation during dark storage over time, different conditions for light soaking, as well as the potential of other approaches: While the repeated flashing is in principle applicable for post UVID-stabilization, current injection procedures showed negligible effect. Interestingly, high-temperature treatment reduces the degradation during dark storage. In that, the study offers insights that may inspire cell-level investigations of degradation and stabilization and improve understanding of underlying mechanisms.

AbstractAccelerated aging tests according to international standards (IEC 61215 and IEC 61730) have been used for many years to investigate photovoltaic (PV) module reliability. In this publication, we share a thorough analysis of the tests that were acquired over a time span of 12 years across a wide range of technologies and module generations. The results can serve as a valuable reference to evaluate the reliability of module types and prototypes beyond the use of standardized pass/fail criteria. Furthermore, this work can contribute to ongoing revisions of these standards. In more technical depth, we share the failure rates of different accelerated aging tests. We further discuss trends that are apparent over the investigated decade and reveal which test sequences have become the most relevant to differentiate different PV module types in terms of reliability.

We propose a safety qualification program for vehicle-integrated photovoltaic (VIPV) modules, which could serve as a simplification, thereby accelerating the homologation process of new vehicle designs. The basis is the current photovoltaic (PV) module safety qualification, as defined in IEC 61730:2016, which is compared to automotive norms and regulations because additional safety requirements have to be considered for PV modules used in this application. Therefore, testing based on regulations that concern electrical and electronic equipment in vehicles (ISO 16750), rupture safety of glass and laminated glass in vehicles (ECE R43), and pedestrian safety (ECE R127) are assessed and compared in terms of severity. Additionally, optional testing concerning the long-term stability of VIPV modules is recommended, as a guideline for vehicle manufacturers. If assessed to be necessary, the qualification program of IEC 61730 is complemented by the respective tests to finally present a conclusive safety qualification program for VIPV modules in new vehicle designs.

Light and elevated Temperature Induced Degradation (LeTID) is likely causing strong yield losses in a significant number of photovoltaic (PV) power plants which were commissioned in the late 2010s. In this work, a procedure for an in-field recovery using overnight current injection to trigger temporary recovery of LeTID is presented. The general feasibility of such a procedure is first demonstrated by climatic chamber experiments on strongly degraded mc-Si PERC PV modules. Within the screened test conditions, a temporary recovery procedure with high currents and low module temperatures is most promising for an economic application in PV power plants. An outdoor experiment with current injection during nights and MPP tracking during days confirmed the possibility to recover LeTID in PV power plants. By injecting a pulsed current, the heating of the modules caused by the current injection was strongly reduced compared to the heating at constant current injection. Recommendations for the application of a procedure in PV power plants are given based on the required energy expenditure and cost.

ABSTRACTTunnel oxide passivated contact (TOPCon) is poised to emerge as the predominant technology in photovoltaic (PV) cells, yet accelerated aging tests point towards significant reliability issues that remain unresolved. This study conducts a comparative analysis of 20 TOPCon PV module types, utilizing a range of electrical characterization and accelerated aging assessments. This investigation provides a detailed evaluation of the electrical performance, resulting in an energy rating of the modules, establishing a benchmark for cutting‐edge TOPCon technology. While some failure modes, such as LeTID, appear to be noncritical, the findings confirm previously identified degradation pathways in TOPCon modules due to moisture penetration. During UV exposure, a novel degradation pattern was observed during the indoor tests, showing severe losses (up to −12% after 120 kWh/m2), followed by recovery after humidity freeze testing, which may influence outdoor performance and the outcomes of certification tests (IEC 61730‐2, Sequence B). The results highlight the areas of need for more targeted testing and technological refinement.