Study of Hybrid Photovoltaic Solar Thermal systems during summer months in Bangladesh

Abstract

A hybrid photovoltaic (PVT) solar system combines a simultaneous conversion of the absorbed solar radiation into electricity and heat. In this study the design of an experimental PVT/dual system, both air & water circulation with modifications in the air channel is presented. First modification is to place a thin flat metallic sheet (TMS) inside the air channel & second one is to use painted Black ribbed surfaces at the bottom of the air channel. To observe the variations of heat transmittance with change of the shape of the ribs four experimental setups with a Trapezoidal, a Saw tooth forward, a Saw tooth backward ribbed surfaces and a flat plate have been used Natural convection is applied instead of forced convection to increase the system net electrical output & thereby the overall system efficiency. All setups of the same capacity, projected area, and water heat extraction method and average depth. Performance study is carried out during the months of February to June, 2012 at IUT campus, Gazipur, Bangladesh. Significant performance has been observed with the above stated modifications. In an intense sunny day of March, the maximum temperature of water is found to be 45ºC for Trapezoidal, 44º C for Saw tooth forward, 43ºC for Saw tooth backward and 41ºC for flat plate setup. Maximum temperature of air inside the air channel is found to be 39ºC for Trapezoidal, 38ºC for Saw tooth forward, 37ºC for Saw tooth backward ribbed surfaces and 36ºC for flat plateȠ in an intense sunny day of march 2012 with an ambient temperature of 34ºC. The average efficiency from all calculated values is found to be 64% for Trapezoidal, 62% for Saw tooth forward, 61% for Saw tooth backward & 58% for flat plate setup.