Empirical Light-soaking and Relaxation Model of Perovskite Solar Cells in an Indoor Environment

Perovskite Solar Cell (PSC) technology is approaching the level of maturity required for some niche applications, primarily in indoor environments. However, their metastability, expressed in the form of the light-soaking effect (LSE), makes it difficult to accurately estimate their expected real-life performance. This work demonstrates a new approach to LSE modelling, which can be used to determine the performance parameters of the PSC based on the history of its irradiance. The model was developed and tested on PSC performance data recorded during one month of operation in a realistic uncontrolled indoor environment, two days of which were used for the tuning of the model and the rest for its verification. The presented model was compared to two static one-diode models, which do not account for the LSE. The energy yield prediction error of the new model was only-0.72 %, the error of the static model based on low-light measurements was +6.96 %, and the error of the static model based on measurements under standard test conditions (STC) was +7.76 %. EY prediction of the low-light static model can however be arbitrarily improved by cherry picking the I-V curve on which to base the model, once the expected result is known. A more meaningful measure of model performance is the mean absolute error (MAE) of the predicted power at the maximum power point PMPP. The MAE of PMPP predicted by the new model was 16.7% lower than that of the low-light static model and 17.1 % lower than that of the STC static model.