Large-area Suns-Voc Tester for Thin-film Solar Cells on Glass Superstrates

Abstract

The Suns-Voc characterisation technique, introduced by Sinton and Cuevas in the 1990s, measures the light intensity (in Suns) versus the quasi-steady-state open-circuit voltage (Voc) of the solar cell under test. The commercially available Suns-Voc tester is limited to sample sizes of about 15×15cm2. In this work, a Suns-Voc tester capable of measuring samples with a size of up to 25×35cm2 is introduced and tested. A good uniformity of the light intensity over the 25×35cm2 area is realised using transparent plastic foils onto which appropriate dot patterns were printed. The optical transmission of these filters is measured and the results are shown to be similar to those of commercial neutral density filters, for the wavelength range 400-1100nm. The 1-Sun and 0.1-Sun light intensity non-uniformities are determined via measurements of the short-circuit current of a calibrated silicon wafer solar cell and are found to be about 3%. We then demonstrate the capabilities of the tester using a large-area polycrystalline silicon thin-film solar cell on glass.