The cell doctor: A detailed ‘health check’ for industrial silicon wafer solar cells

By Armin Aberle, CEO, SERIS, National University of Singapore; Bram Hoex, Director and Group Leader of Silicon PV Cluster, SERIS, National University of Singapore; Ian Marius Peters, Head of the Simulation Group, SERIS, National University of Singapore; Rolf Stangl, Senior Research Scientist, SERIS, National University of Singapore

In principle solar cells are very simple: they convert sunlight to electricity and can be characterized by a single number – the solar cell efficiency. Manufacturers obviously want to achieve this efficiency at the lowest possible cost, so it is critical that the efficiency/cost ratio be optimized. To this end, knowledge of where the biggest gains can be achieved is key. This paper presents an in-depth loss analysis method developed at the Solar Energy Research Institute of Singapore (SERIS) and details how various losses in a silicon wafer solar cell can be quantified, which is not done in the case of a conventional solar cell measurement. Through a combination of high-precision measurements, it is shown that it is possible to fully quantify the various loss mechanisms which reduce short-circuit current, open-circuit voltage and fill factor. This extensive quantitative analysis, which is not limited to silicon wafer solar cells, provides solar cell researchers and production line engineers with a ‘health check’ for their solar cells–something that can be used to further improve the efficiency of their devices.