Impact of Shunt Resistance on the Performance of Curved Thin-Film Photovoltaic Modules With Series-Connected Solar Cells

Abstract

Curved photovoltaics (PV) is gaining widespread application in modern energy-efficient infrastructure, wearable electronics, and vehicles. Due to the different orientations of the solar cells in curved PV modules, current mismatch between solar cells is more prevalent in curved PV than conventional flat PV. In this article, we investigated the effect of shunt resistances, which can mitigate current mismatches in series-connected solar cells, on the performance of curved thin-film PV modules. A flexible 85 × 80 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> Cu(In,Ga)Se <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> mini-module composed of 17 series-connected solar cells on a curved surface was characterized experimentally and theoretically. We found that the short-circuit current of the curved PV module is affected by all the solar cells connected in series and is not simply determined by the current-limiting solar cell. The current-voltage characteristics of a curved PV module are well described by a simple model that includes low shunt resistance. The power generated from normal irradiance decreases with shunt resistance; however, the power for tilted illumination is higher than that of a module without shunt resistance. This indicates that the low shunt resistance can suppress the power loss due to current mismatch. In addition, curved PV modules cause self-shading under highly tilted illumination but curved PV modules with low shunt resistances provide power even when some solar cells are not illuminated. Furthermore, sudden current mismatches in solar cells, which generate detrimentally high reverse biases can be eliminated by the shunt resistance. This confirms the protective effect of the shunt resistance to enhance the durability of curved PV modules.