Energy rating based on thermal modelling of five different PV technologies

Abstract

Minute by minute outdoor measurements of five commercial PV modules including multi c-Si, HIT, a-Si/μc-Si, CIS, CdTe over one year were used to develop a model for predicting the individual module temperatures. The simulated module temperatures over a whole year in minute interval correspond to the outdoor measured values within a RMSE of 1.5°C. Input of the model includes irradiance measurements, which are extracted from the measured short circuit current ISC, the measured wind speed and the ambient temperature. The measured energy weighted module temperature for Zurich was found to be between 33.3°C and 38.0°C for the different module types with a maximum difference of 0.8°C relative to the simulated average module temperature. Due to the high module temperature, the annual average efficiency was reduced relative to the STC values by only 2.6% (HIT) and 5.6% (CIS). Another reduction of the STC efficiency could clearly be attributed to the efficiency at low ISC values which classify low irradiance values. The value is a decrease of the annual energy output of 4.7% and an increase of 1.1%. A further loss analysis was performed to separate spectrum related losses resulting in a relative difference of 2% for the tandem compared to the multi c-Si module