Performance Evaluation of Photovoltaic Modules by Combined Damp Heat and Temperature Cycle Test

Abstract

Standard damp heat (DH), temperature cycle (TC), and combined DH-TC tests were performed using monocrystalline Si 72-cell modules with a conventional ethylene vinyl acetate (EVA) encapsulant, and their module performance and electroluminescence images were investigated. During the DH test, a significant drop (~20%) in the maximum output power of the module was noticed, primarily because of the degradation of fill factor and an increase in series resistance at 5500 h of DH testing (DH5500), presumably due to the corrosion of metal electrodes by moisture ingress. Conversely, it was revealed that temperature cycling did not seriously degrade module performance until 1400 cycles. However, the combined DH5000-TC600 test suggested in this study, with a sequence of DH1000-TC200-DH1000-TC200-DH1000-TC200-DH2000, was confirmed to provide harsher conditions than the DH-only test by causing a 20% decrease in maximum output power (Pmax) after DH3000/TC400. Promisingly, we confirmed that the module with a polyolefin elastomer encapsulant showed better durability than the module with EVA even in the combined DH-TC test, showing a limited decrease in Pmax (~10%) even after the DH5500/TC600 test.

Analysis of Accelerated Damp Heat Test for Degradation Analysis and Recovery Method of Photovoltaic Module

“…Table 2 and Figure 1 demonstrate the statistical analysis of degradation characteristics of module performance parameters such as V oc , I sc , FF, and P max after 1000 h of DH testing at 85 °C/85%RH with measurement intervals of 300 h and 400 h. The P max value of the testing module was maintained at ≈90% of its initial value (i.e., a loss of less than 10%) until 1000 h. It can be assumed that the encapsulant effectively prohibited moisture penetration through the 1000 h DH test because the FF decreased by only ≈2.6%. In this testing condition, the P max is degraded from 19.55 ± 0.46 to 17.90 ± 0.16 after 1000 h. To degrade the P max of the module, the DH test should be extended to at least 3000 h to see noticeable degradation, [ 24 ] which consumes considerable time and resources.…”

“…[ 21 ] Furthermore, the EL images taken after 600 h at 120 °C/85%RH (presented in Figure 4c) confirmed that the dark regions were widely common throughout the entire module surface. This condition was equivalent to the DH test at 85 °C/85%RH for ≈6000 h. [ 24 ] The degradation is more at higher temperatures as incresases in temperature are imlicated in several failure or degradation modes of PV module, because elevated temperature increases stresses associated with the thermal expansion and also increases the degradation rates by a factor of about two for each 10 °C increase in temperature. Significant losses in PV module performance are caused by the corrosion of the cell, that is, the SiN x antireflection coating, or the corrosion of metallic materials, that is, solder bonds and Ag fingers.…”

Statistical analysis and degradation pathway modeling of photovoltaic minimodules with varied packaging strategies

“…In the same study, DH with temperature cycling (DH5000/TC600) revealed that POE showed better durability than EVA. In both the cases, the power loss followed a change point trend and the series resistance increased faster for EVA module than the POE one Park et al (2021). In another work by Oreski et al (2020) upon 3000 h of DH exposure, only EVA-based modules were seen to have corrosion at the silver grid as well as above the ribbons; modules with POE displayed no corrosive effects.…”

“…Even though our study does not consider packaged c-Si cells in particular, moisture ingress could be a possible explanation to why GB minimodules experience more power loss in our study. Moisture ingress is known to be initiated from edges of modules Poulek et al (2021); Park et al (2021). In another independent study by Kumar et al (2022) GB 10.3389/fenrg.2023 minimodules with EVA were seen to have increased series resistance at high humidity levels.…”

“…Many studies in literature implement DH as the predominant indoor exposure condition. In a study by Park et al (2021) DH test (for 5500 h) was performed on p-PERC GB modules with EVA; an increase in fill factor and series resistance was observed due to corrosion of metal electrodes by moisture ingress. In the same study, DH with temperature cycling (DH5000/TC600) revealed that POE showed better durability than EVA.…”