Dark and illuminated characteristics of photovoltaic solar modules. Part I: Influence of dark electrical stress

Abstract

International audienceThe main idea is to study the effect of reverse stress current on solar cells under illuminated conditions. More specifically the characteristics (I-V) and parameters were studiedin dark and illuminated conditions at room temperature for several common periods of time. For the numerical analysis of this work a double exponential model is used. The changes in characteristics which are caused from the effect of a reverse current introduced for different stress levels simulated the effect of accumulated extreme reverse currents that can occur in the solar cells and modules as result of shading and other different reasons. The paper originally contributes to the research on the adverse effects of reverse currents on the normal functioning of cells and solar modules

Confirmation of the Degradation of Single Junction Amorphous Silicon Modules (a-Si:H)

“…This also relates to the recombination current within the module. The presence of a hot spot is believed to create weak regions in PV modules; this forces the electrons to flow in the reserve path of the p-i-n junction [40,72]. The third region of the semilog I-V curve extends from 15 V to 25 V, which is the range of a nominal operation voltage, and this region is associated with a high Figure 12, the combined semilog I-V is presented; the semilog of the short current I sc was extracted from the respective figures.…”

“…This is confirmed by the breakpoints in the curves. The I-V curve characteristics in Figure 4 show that module 3 had slightly mismatched cells in its series circuit connection [38][39][40][41]. However, the slope of each curve, judging from point V = 0, indicates a slight difference in their series resistance.…”

Analysis of defects of PV solar modules using deep level transient spectroscopy. Feasability and limits

“…In this experiment, we use commercial solar modules 4x4 (16 cells) 2V, 60 mA and 0.12W, collected from the local consumer market. The DLTS was measured in dark condition for different temperatures levels between 140-291K, before and after stresses (electrical, thermal) [4,6] by adjusting 10 min for each dose of stress.…”

“…This DLTS technique is a complementary performant method of indirect measurements of semiconductor junction defects, as for example, techniques used in the Ref. [4][5][6] and [7,8] based on I(V) and C(V) characterizations. Thus, the DLTS technique is one of the most performant techniques for characterizations of internal defects in semiconductor juntions [9][10][11].…”

Enhanced model of photovoltaic cell/panel/array considering the direct and reverse modes

“…[1][2][3][4][5][6] and by Zaraket et al in Ref. [7][8][9][10] who have experimentally studying the influence of electrical and thermal stresses on cell efficiency, shadow induces the PV cell to act as load and to consume the power delivered from other un-shading cells, thus inducing a rising of its temperature reaching creation of hot spot. Therefore, the authors in [11] have originally proposed a direct and reverse mode model (named DRM model) able to describe I-V characteristics in both direct and reverse operating mode according to the experiments made on the reverse mode biasing of 60 polycrystalline silicon cells.…”