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Copper indium gallium diselenide (CIGS) based technology is actively competing in the global photovoltaic market with high conversion efficiency. Commercial CIGS modules are anticipated to perform on rated output in the field condition for 20 years. Potential induced degradation (PID) is considered as one of the critical concerns among all the current reliability assessment issues. PID accelerated tests have been performed on pre‐commercial CIGS modules to investigate reduction in electrical performance. We report the severe reduction in electrical performance after PID is correlated to the microstructural and chemical properties of the constituent materials. Under extreme PID stress, the cell surface reveals various defects including crater formation. The aim of this article is to explore the consequences of PID induced craters on the efficiency of CIGS solar cells by investigating material degradation kinetics. In this perspective, we present the root cause of PID in CIGS thin‐film modules in relation to microstructural defects by detailed investigation using J‐V analysis, field emission scanning electron microscope (FESEM), Raman spectroscopy, X‐Ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL). This analysis can provide more effective and sustainable research strategies to cultivate more efficient and reliable CIGS technologies in the long run.

A round robin test was carried out in four PV laboratories to compare accelerated lifetime testing. Twenty commercial non-packaged CIGS solar cells of similar performance were spread and exposed to damp heat conditions (85 °C and 85% RH) for approximately 500 h. Their JV performance was monitored during the damp heat exposure. After the test, three of the labs reported average efficiency losses of 87 ± 4%, 89 ± 5% and 92 ± 1%, which are close to median degradation rates found in literature. A higher degradation rate (efficiency loss of 97 ± 3% after only 143 h) was observed in the fourth lab. This was attributed to a poorly designed ceiling window sealing, which caused liquid water pooling on the samples. After modifying the climate chamber, the experiment was repeated with similar samples and an efficiency loss of 72 ± 6% after 475 h was observed for this lab.

Recent research has shown that bifacial PV modules with a glass/glass packaging are prone to different PID mechanisms occurring simultaneously on the front and the rear side of the solar cell. With this in mind, researchers investigating the impact of PID on each side of the bifacial solar cell separately apply PID stress to one side of bifacial PV modules according to stress method (b) as described in the IEC TS 62804-1, that is, contacting the surface with a conductive electrode. Yet, in this paper, we show that such practice of PID testing might result in an unintended development of an electric field between the environmental chamber and the nonstressed side of the solar cell. Through our experimental study, we reveal that this electric field results in unintended bifacial PID stress of bifacial solar cells, which goes along with misleading interpretations of the evolving PID mechanisms and susceptibility of bifacial PV modules. Next to the methodology concerns, we discuss three possible solutions to prevent such unintended PID mechanisms from occurring.

Potential-induced degradation (PID) of photovoltaic (PV) modules gets a lot of attention since 2010 when Solon published their findings about a degradation mechanism in their PV modules caused by high potential differences between the solar cell and the grounded frame [1]. Module level efficiency drops of 30% and more caused by PID have been reported [2], [3]. A stress test for PID according to IEC 62804 and a recovery test in the same conditions were conducted on a set of 49 commercially available PV modules. In this paper we report the irreversibility of highly affected (i.e. over 85% PID) PV modules. From this point of view, it is important to detect and recover PID before the point of no return. Furthermore, the impact of PID on the different parameters of a PV module and their relevance in order to detect PID in the field are reported.

An interlaboratory test involving four PV laboratories was carried out to compare performance measurements using nonencapsulated CIGS solar cells. 15 samples were sorted according to their electrical parameters measured in the first lab and distributed to the three remaining ones, where the cells were remeasured. The comparison of the cells performance showed significant differences between the tested institutions, with variances in Voc, Jsc and FF. The method for contacting the cells, as well as the hardware and software used, were identified as the probable causes for the differences, suggesting that improvements in methodology and equipment, as well as constant monitoring, are necessary to assure the reliability of the measurements.

The combination of increasing operational voltages beyond 1000 V in photovoltaic (PV) installations and the emergence of new PV technologies requires a critical assessment of the susceptibility to potential-induced degradation (PID). Since this failure mode can trigger significant and rapid power losses, it is considered among the most critical failure modes with a high financial impact. Insights in the physical mechanism of the performance loss and its driving factors are critical to develop adapted characterization methods and mitigation solutions. PID in p-type solar cells is triggered by sodium (Na) that diffuses into stacking faults of the silicon lattice, causing shunt paths through the pn-junction. In addition, it is hypothesised that for bifacialp-PERC solar cells positive charges, such as Na+, accumulate in/on the negatively charged AlOxrear passivation layer due to the potential difference between the glass and the rear cell surface. This significantly increases surface recombination. However, the degradation behaviour observed in bifacial monocrystallinep-PERC solar cells under PID stress from both sides (bifacial PID stress) does not match with just one of the degradation mechanisms. A comprehensive test matrix was carried out to understand the physical origin of PID in front emitter bifacialp-PERC solar cells in a glass/glass packaging. The results show that bifacialp-PERC solar cells under bifacial PID stress suffer from both shunting of the pn-junction and increased surface recombination at their rear side. Hereby, we prove that the glass/glass packaging in combination with bifacial solar cells can significantly increase the severity of PID.

This study has received funding from the project PV OpMaat, financed by the cross border collaboration program Interreg V Flanders-Netherlands with financial support of the European Funds for Regional Development. B.C. is a postdoctoral fellow of the Research Fund Flanders (FWO).

Microwire arrays are a powerful tool for the exertion of localized thermal stress on cellular networks. Combining microwire arrays with a set of orthogonal axon-guiding microchannels on-chip allows for the positioning of neurites, as well as control over their polarity. In this paper, we present a new fabrication approach, based on standard clean room fabrication and sacrificial layer etching, for the integration of microwire arrays into neurite guiding structures. The system permits the application of strong temperature gradients, enabling localized thermal stimulation inside microchannels.