Investigation of bias radiation effect on PV cell measurement

Abstract

Photovoltaic (PV) cells are photo-electrical devices that convert light energy directly into electricity through the photovoltaic effect. PV cell assemblies are used to make solar modules employed in a variety of ways ranging from space applications to domestic energy consumption. Characterisation and performance testing of PV cells are critical to the development of PV technologies and growth of the solar industry. As new solar products are being developed, its energy conversion efficiency and other critical parameters must be accurately measured and tested against globally recognised metrological standards. The differential spectral responsivity (DSR) measurement is one of the primary methods for calibrating reference PV cells. This is done by calculating its spectral responsivities through measuring the AC short-circuit current produced by a PV cell under a modulated monochromatic radiation and different levels of steady-state broadband bias light radiation. It is observed that different types of bias light source will produce different signal-to-noise levels and significantly influence measurement accuracy. This paper aims to investigate the noise sources caused by different types of bias light sources (e.g. xenon arc and tungsten-halogen lamps) and the relevant measurement uncertainties so as to propose a guideline for selection of bias light source which can improve the signal-to-noise level and measurement uncertainty. The DSRs of the PV cells are measured using a commercial DSR measurement system under different levels of bias radiation from 0 to 1 kWm-2. The data analysis and uncertainty evaluation are presented in this paper using experimental data and mathematical tools. © 2013 SPIE.