Performance of the first flight experiment with dedicated space CIGS cells onboard the Delfi-C3 nanosatellite

In this paper we analyze and explain the performance of CIGS on Ti cells which have been mounted in the Dutch Delfi-C³ nanosatellite that was launched in April 2008. The CIGS experiment includes several novel technologies for thin film solar cells in space. A new interconnect method based on pressure contacts between the cells was developed to minimize stresses between the electrical contacts. A thin protective coating was developed especially for a high emissivity. An electrical model is presented to predict the electrical characteristics. The thermal properties of the cells have been modeled and simulated. Effective cell temperatures in space were in between -100°C and 82°C. The following measurements were taken: IV-curves, indirect cell temperatures and irradiance in the array plane. The monitoring fraction was 1.4 %. The efficiency at 25°C was 10.3 % at 700 W/m² irradiance. The performance in space has been compared to solar simulator measurements in the laboratory. The performance after three months in space is equal to laboratory measurements for all four solar arrays. There has been no indication of degradation during the first three months.