Experimental Study of the Spectral and Angular Solar Irradiance

We developed an experimental set-up and procedure to measure spectral and angular solar irradiance to accurately predict and optimize solar power plant performance. The set-up is comprised of a fiber coupled spectrometer mounted to a rotational stage which allows for 360⁰ light capture. The lightweight and flexible design enables irradiance measurements at any location. Measurements were taken in Enschede, Netherlands and in Phoenix, AZ, USA. We find a strong dependence of spectro-angular irradiance on the location, surroundings and cloud coverage which needs to be considered when modelling and optimizing location dependent solar power plant output. Index Terms — Bifacial solar cells, spectral albedo, spectral and angular irradiance, solar irradiance measurements.