Photovoltaic Warm Façades with Phase Change Materials in European Climates

Abstract

Since façade-integrated photovoltaic (PV) modules heat up greatly, which reduces the efficiency of the PV, façade panels with PV and phase change materials (PCM) were developed. PCMs absorb a significant amount of thermal energy during the phase transition from solid to liquid, while maintaining a specific melting temperature. This cools down the PV and increases the electrical yield. Numerical studies on PV-PCM warm façades without rear-ventilation have so far been missing. Therefore, a thermal and an electrical simulation model for PV-PCM warm façades were developed and validated. They were then used to analyse the yield increase of two PCM-types and -quantities in PV warm façades facing east, south, and west in Athens, Potsdam, and Helsinki. An annual yield increase of 1.2% to 8.5% for monocrystalline PV modules was determined. The maximum monthly yield increase is 8.0% in Helsinki, 11.4% in Potsdam, and 11.3% in Athens. The study shows that a case-specific selection of the appropriate type and quantity of PCM is necessary. Using the models, a design tool for PV-PCM warm façades will be developed. It will be validated with real monitoring data from PV-PCM façade test rigs at the Technische Universität Dresden and the National Technical University of Athens