الفهرس 
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Abstract
Photovoltaic cells are produced by semi-conducting materials to convert the solar light energy into electricity and during this process heat is absorbed by the solar radiation. This heat causes a loss of electricity generation efficiencies. In order to solve this problem, several different cooling techniques can be utilised to more effectively dissipate heat from the PV module. In this study, an experimental setup was designed and established to test two separate photovoltaic module systems with alone PV and with water cooling system (PV/Thermal) to investigate the heat effect on PV systems. The absorbed heat energy behind the photovoltaic cell’s surface in insulated ambient is removed by means of water cooling system and the tests for both PV and PV/T systems were simultaneously performed along June 2014. It is found that without active water-cooling, the temperature of the PV module is higher during daytime and solar cells could only achieve around 8.1% electric efficiency. On the other hand, when the PV module was operated with active water-cooling, the temperature dropped significantly and leading to an increase in the electric efficiency of the PV/T module with cooling as much as 11.1% with maximum performance enhancement is 35% at 1.00 pm. The maximum thermal conversion efficiencies of the system are determined as 42.7%, 46% and 52% for three different volume flow rates. It is observed that water flow rate is effective on increasing the electric conversion efficiency as well as absorption and transition rates of cover glass in PV/T system. As a conclusion, the conversion efficiency of the PV system with water-cooling might be improved. Therefore, it is recommended that PV systems should be designed with most efficient type cooling system to enhance the efficiency and to decrease the payback period.
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In the second part of the experimental work, dual axis sun-tracking systems is designed whereby the movement of a PV module is controlled to follow the Sun’s radiation using a Programmable Logic Controller (PLC) unit. It is found that the daily output power of the PV is increased up to 13.27 % in comparison with that of a fixed module. Also, the concentration of solar radiation lead to increase in the movable module surface temperature up to 14 °C compared to the fixed module during the early hour of the day as a result of the significant increase in solar radiation during this period of the day. Hybrid cooling system combined between PV tracking and cooling systems reduces the movable module surface temperature up to 10 °C compared to the non-cooling movable module, with 7.53°C average daily reduction. Causing an increase in module daily output power up to 26% compared to non-cooling fixed module, with increased 9.8 % over than that produced from non-cooling movable module.
Keywords: Poly-crystalline cells, Solar cell parameters, Photovoltaic thermal systems, Conversion efficiency, Water cooling, tracking system, Hybrid, PLC.