Performance Evaluation of a Hybrid Photovoltaic Solar Thermal System

Abstract

Hybrid photovoltaic/thermal (PV/T) system consists of a solar photovoltaic panel and a heat extraction unit, which are mounted together. These systems can simultaneously provide electrical and thermal energy, thus achieving a higher energy conversion rate of the absorbed solar radiation than the conventional photovoltaic systems. In this study a hybrid PV/T system was designed and manufactured, both air and water circulation was considered with modifications in the air channel. First modification was to place a thin flat metallic sheet (TMS) inside the air channel and second one was to use painted black ribbed surfaces at the bottom of the air channel. To observe the variations of heat transmittance with different shape of the ribs four experimental setups with a trapezoidal, saw tooth forward, a saw teeth backward ribbed surfaces and a flat plate were used. Natural convection was applied instead of forced convection to increase the system’s net electrical output & thereby the overall system efficiency. All setups were of the same capacity, projected area, average depth and water heat extraction method. The experiment was carried out during the months of February to June, 2018. Significant improvement in the performance was observed with the above stated modifications. In an intense sunny day of March, the maximum temperature of water was found to be 45°C for Trapezoidal, 44°C for Saw teeth forward, 43°C for Saw teeth backward and 41°C for flat plate setup. Maximum temperature of air inside the air channel was found to be 39°C for Trapezoidal, 38°C for Saw teeth forward, 37°C for Saw teeth backward ribbed surfaces and 36°C for flat plate in an intense sunny day of march 2018 with an ambient temperature of 34°C. The average efficiency from all calculated values is found to be 64% for Trapezoidal, 62% for Saw teeth forward, 61% for Saw teeth backward and 58% for flat plate setup.