The temperature of Photovoltaic (PV) module rises by absorbed incident solar radiation and causes subsequent drop off in electrical efficiency. To overcome this ill effect, an appropriate material must be used to absorb the heat and maintain the temperature of PV module. The purpose of present study is to review and understand various cooling techniques used to enhance cooling and electrical performance. The emphasis was placed on design and operating parameters like absorber configuration, flow pattern, flow rates, climatic conditions, radiation intensity, wind speed, thermal conductivity, glazing, concentration on the electrical and thermal characteristics. The reviewed papers include theoretical analysis, computer simulation, solar simulator and on-field experiments. The study states that the proper selection and utilization of cooling technology, design and process parameters are the key elements in the solar photovoltaic (PV) system to achieve optimum performance.

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In this paper, a novel thermal absorber based photovoltaic thermal system is presented. The thermal absorber is attached at the rear surface of photovoltaic, and water is re-circulated to extract heat. The outdoor experimentations are performed at Pune, India (18.7611?N, 73.5572?) on clear sky day, and water temperatures, surface temperature, radiation and flow rate are measured to analyze techno-economical performance at different operating conditions. The surface temperature of the photovoltaic module plummeted from 54.65?C to 47.9?C with the incorporation of a thermal absorber with flipside water cooling at a ranging flow rate of 0.03 to 0.06 kg/sec. The result shows an average enhancement of 4.2 % in the electrical power output of the photovoltaic thermal system. The maximum thermal and electrical efficiencies were 47.82 % and 9.88 %, respectively, at 0.06 kg/sec. The exergy efficiency was found in the range of 9.85-14.30%. Based on the experimental evaluation, uncertainty analysis was performed. The results revealed that the annual CO2 mitigation for photovoltaic and photovoltaic thermal system was 225.46 kg/annum and 464.8 kg/annum, while simple payback periods were 4.53 years 3.03 years, respectively. The analysis offers an efficient estimate of experimental features of photovoltaic and photovoltaic thermal systems from an energy-exergy, environmental and cost-benefit standpoint.

In Photovoltaic thermal (PVT) System, Nanofluid and its structure plays an important role in cooling photovoltaic panels. It is introduced as a non-conventional active/passive cooling method to improve the performance of the PVT system. A PVT system consists of several components such as solar panels to absorb and directly convert sunlight into electricity, ducting for fluid flow, supporting structure and accessories. A Nanofluid is a mixture of base fluid and nanometre sized particles such as metals, oxides and carbides. In the current work, attempt is made to review application of Nanofluid in the PVT system for better energy conversion efficiency. Keywords: Nanofluid; Hybrid PV/T System; Thermal conductivity; PV/T Performance; PV/T Cooling I. INTRODUCTIONThe energy from the sun can be converted into heat or electricity with the help of solar collector. With compare to low grade energy (heat) extraction in the form of high grade energy (electricity) is always preferred due to wide range of application and conversion efficiency. With the discovery of photovoltaic effect, solar energy can be easily converted into Electrical Energy with help of Photovoltaic cells. At present, the Photovoltaic cells have lower conversion efficiency which is less than 20% and remaining 80% of energy converted in the form of thermal energy. The thermal system has comparatively good efficiency but has lower grade of energy. The main reason behind the decrease in electrical efficiency of the PV panel is the increase in the module temperature of the PV. As due to Overheating of PV/T cells causes Reduction in Efficiency. The dissipation of heat can be done by supplying Nanofluid through duct or piping arrangement. NanoFluids are Solid-Liquid Composite materials which has the Ability to transfer heat across a small temperature difference. It enhances the efficiency of Energy Conversion. It contains Nanometer sized particles called Nano-Particles. Nanofluids are new generation Heat Transfer Fluids for various types of Applications.