Technology Focus: Photovoltaics

Crystalline silicon is the workhorse of the photovoltaic power industry, making up about 95% of the modules sold in 2017. There are only two significant companies supplying anything else, as of December 2018: US-headquartered First Solar Inc making cadmium telluride modules, and Japanese Solar Frontier KK making copper indium gallium selenide (CIGS) modules. Both are considered ‘thin film’ technologies, i.e. the process of making the modules involves depositing the semiconductor onto glass as a vapour and letting it crystallise in place in a layer a few microns thick. This is in contrast to the standard crystalline silicon type, where the semiconductor (silicon) is first crystallised into a block (ingot) and then cut it into slices at least 100 microns thick, a batch process with significant wastage (Table 18.1)…