Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
Thermal models and correlations for the convection heat transfer coefficients are mainly for isothermal or constant beat flux surfaces and can result in discrepancies of up to 50% in the prediction of surface temperatures or heat fluxes on Photovoltaic (PV) panels. An experimental investigation was conducted to develop the thermal models and correlations for natural convection on a vertical PV module with non-isothermal surfaces. The paper also reports on the PV configuration with the maximum electric efficiency and natural convection cooling. A proximity mobile probe with two K-type thermocouples was developed to measure simultaneously local surface and air temperatures on the PV surface at a fixed distance. Thermocouples, anemometers, voltmeter, ampere-meter and Lux-meter were interfaced to a computer and sampled at a rate of 6 samples per minute (one every 10 second). The electric energy conversion efficiency and the natural convection cooling were quantified for the dimensionless channel spacing of s/h=0.015, 0.0.3, 0.045, 0.06 and 0.075 on a PV with a single glazing. An optimum configuration for a PV with single-glazing and the channel spacing of s!h 0.06 was selected for its maximum efficiency and natural convection cooling and proposed to be retrofitted on the existing UTS buildings.