Abstract

We have developed a setup for measuring differential spectral responsivities of unifacial and bifacial solar cells under bias light conditions. The setup uses $30$ high-brightness LEDs for generating a quasi-monochromatic light source covering the wavelength range $290–1300~\text{nm}$. Halogen lamps are used to generate bias-lighting conditions up to the irradiance level of $1000~\text{W}/\text{m}^2$. The setup has been fully characterized for spectral irradiances and spatial uniformities of all light sources. Validation measurements carried out using a reference cell of $2\times2~\text{cm}^2$ area from Fraunhofer ISE demonstrated an agreement better than $2\%$ over the wavelength range of $425–940~\text{nm}$, with an expanded uncertainty of $2.6\%$. In the UV and IR regions, the discrepancies are higher but still within estimated uncertainties. The setup is also tested in measuring spectral responsivities of large $15\times15~\text{cm}^2$ bifacial solar cells. The associated problems are discussed.

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