Delfi-C³ Thin Film Solar Cells Payload
Thin Film Solar Cells (TFSC), developed by Dutch Space, are tested onboard Delfi-C³. It's performance over time is verified by measuring two key characteristics of photovoltaic cells: the IV-curve related to the temperature. In total four solar cell assemblies are measured by two electrical boards.
The Thin Film Solar Cell is an innovative development by Dutch Space (www.dutchspace.nl). The cells consist of a CIGS photovoltaic layer which is deposited by evaporation on a titanium base layer of 25 micrometers. The aim of this new type of solar cell is to create a light-weight and low-cost product for future space applications. The target is a 50% cost reduction of solar arrays, while improving the power to mass performance with 50% compared to conventional solar cells. Cost is projected to be lower than 350 Euro per Watt at solar array level, and the power is expected to be more than 100 Watt per kilogram. The cell will have no need for a cover glass, but it will have an emissivity‑enhancing and encapsulating dielectric coating. The efficiency is about 12 % under AM0 light conditions.
A total of eight measurement points are taken of each TFSC assembly to reconstruct the current-voltage (IV) curve. First the short circuit current is measured. From this first measurement, the other 7 points are measured by taking a percentage of this measurement through switching resistors with fixed values. In order to measure the temperature of the TFSCs a strip is used as an RTD temperature detector.
A paper has been published on the results of the TFSCs in the proceedings of the IEEE Photovoltaic Specialist Conference in 2010.