Enhancement of Conversion Efficiency of Thin Film Photovoltaic Cells by Applying Forced Convective Cooling With Underground Cooled Air

Abstract

Photovoltaic (PV) cells also called Solar cells are electronic devices that convert sunlight directly into electricity. There are two prominent PV cell technologies viz. wafer-based crystalline silicon Solar cells and Thin Film Solar cells in the market today. The efficiency of wafer-based crystalline as well as Thin film Solar cells get reduced with increase of panel temperature. It is noted that the efficiency drops by about 0.5% for increase of 1° C of panel temperature. It is necessary to operate them at low temperatures to keep the PV module electrical efficiency at acceptable level. Therefore need for a low-cost cooling system for the Solar panels is felt. newlineThe cooling of Photovoltaic cells is a problem of great practical significance. It has the potential to reduce the cost of solar energy in three ways newline(a) The electrical efficiency of Photovoltaic cells decreases with temperature increase. Cooling can improve the electrical production of standard flat plate PV modules. newline(b) Cooling makes possible the use of concentrating PV systems. Cooling keeps the PV cells from reaching temperatures at which irreversible damage occurs. newline(c) Heat removed by the PV cooling system can be used for domestic or industrial applications. newlineThe various methods for cooling of panels are discussed briefly. newline(i) Hybrid PV-T systems: Here fluid is run through the rear of the panels which absorb the heat. This concept offers an opportunity to increase overall efficiency by making use of waste heat generated in the PV module. newline(ii) Natural /Forced convection of air : The transfer of heat between a solid boundary and moving air takes place by a combination of conduction and convection. newline(iii) Use of Heat Pipe: Heat Pipe is a device for transferring heat from a source to sink by means of evaporation and condensation of a fluid in a sealed system. newline(iv) Heat Sink: Fins are attached at the rear face of the panel.(v) Mist sprays (Evaporative cooling) : The Solar panels are cooled by spraying them with a mist of water. newline(vi) Micro-channel cooling :