Weak Light Performance and Spectral Response of Different Solar Cell Types

A large number of possible PV-powered products should be able to operate under indoor lighting conditions. In order to make good product designs of indoor operated PV-devices (ipv), a more extended dataset of PV characteristics than just standard test condition (STC) parameters is required. Within the SYN-Energy project framework, which aims to improve design methods for PV-powered consumer devices, this paper presents results of IV-curves measured for solar cells of different technologies at irradiance levels between 1...1000W/m. The resulting European cell efficiencies are calculated. In addition, measurements of the spectral responses at different bias light intensities and spectra were performed. By adopting the measurement findings to indoor irradiation scenarios, we outline the impact on ipv energy yields regarding spectral response and the efficiency decrease towards low light levels. This is performed by applying a simplified daylight factor approach to the measured characteristics of commercial available PV at lower/indoor light levels and implementing solar cells spectral response using de-rating factors.