Enhancement of daily and monthly electrical power of off-grid greenhouse integrated semi-transparent photo-voltaic thermal (GiSPVT) system by integrating earth air heat exchanger (EAHE)

•The daily electrical power is increased due to cooling effect of semi-transparent PV module roof of greenhouse integrated semi-transparent photo-voltaic thermal (GiSPVT) by earth air heat exchanger (EAHE).•Mathematical thermal modeling of off-grid greenhouse integrated semi-transparent photo-voltaic thermal (GiSPVT) system by integrating earth air heat exchanger (EAHE) is carried out under quasi-steady state condition.•Analytical expressions for solar cell temperature and its electrical efficiency, room air and plant temperatures is derived.•An overall daily exergy of GiSPVT system has been calculated. In this communication, an attempt has been made to evaluate daily and monthly electrical power of off-grid greenhouse integrated semi-transparent photo-voltaic thermal (GiSPVT) system by integrating with earth air heat exchanger (EAHE) under quasi-steady state condition which has not been considered earlier. The analysis is based on basic energy balance equations which are function of climatic and design parameters. Analytical expressions for solar cell temperature and its electrical efficiency, room air and plant temperatures have been derived. Numerical computations have been carried out for a typical day by MATLAB program. The results have also been compared with respect to without earth air heat exchanger (EAHE). Based on outcome of numerical computation, the daily electrical power is increased by 7.5% due to cooling effect of semi-transparent PV module roof of GiSPVT by EAHE. An overall daily exergy of GiSPVT system has been found to be 4.60 × 107 Wh for a packing factor of 0.22. The monthly output of off-grid GiSPVT system is obtained as 861.28 kWh. Finally, the theoretical model has also been validated by experimental results of a typical winter climatic condition without earth air heat exchanger (EAHE) for climatic condition of Ballia (UP), India.