EFFECT OF PHOTOVOLTAIC COMBINED HEAT PUMP SYSTEM ON ENERGY PRODUCTION: AN EXPERIMENTAL OPTIMIZATION

This study addresses the efficiency decline in photovoltaic (PV) systems due to increased cell temperature. The aim is to find solutions to this fundamental problem in electricity generation from solar energy, which is a pressing concern in the field of renewable energy. The electrical efficiency of the PV system reaches its peak at a cell temperature of 25°C, at which it operates with a yield of around 13% under 1000 W/m<sup>2</sup> irradiance. As the cell temperature increased from 25°C to around 34°C, there was a significant and constant decline in electrical efficiency. At steady-state conditions, the electrical efficiency of PV cells was observed to have decreased from approximately 13% to approximately 8% under 1000 W/m<sup>2</sup>, which corresponds to a decline around 38%. In order to cool down the PV panel to prevent this decline and to supply heat to the heat pump system, an industrial heat pump system that operates on a closed cycle using R-134a refrigerant was coupled with the PV system as having its evaporator in tight contact with the back of a 100-W PV panel to set up a photovoltaic thermal heat pump system (PV/T-HP). The PV/T-HP system performance was investigated for three levels of three system parameters (irradiance, condenser mass flow rate, and capillary tube length) through the utilization of the response surface method (RSM), seeking to identify the parameter that had the greatest impact on the heat pump's coefficient of performance (COP). The capillary tube length was found to have the greatest impact, yielding highest COP with 2-m tube length. A remarkable decline in electrical efficiency was observed when the cell temperature rose from 25°C to around 34°C, dropping from approximately 13% to about 8%. The highest COP of 2.61 and the highest efficiency of 0.12 were achieved at optimum conditions.