The average thermal efficiency as modelled in TRNSYS was 22%. This value for thermal efficiency agrees with values for thermal efficiency as illustrated in graphical results of Tonui and Tripanagnostopoulos [10] for a PVT system with a channel depth of 0.15m. The convective top heat loss coefficient of the PVT system varies with wind speed according to the equation used by Cox and Raghuraman [11],

hg = 1.247 x[ — Ta)x cos#] + 2.658 x Vw (5)

where hg is the convective top heat loss coefficient from the glass cover, Tg is the temperature of the glass cover, Ta is the ambient temperature, 0 is the tilt angle and Vw is the wind velocity. The simulated values for the convective heat loss coefficient were reasonably high as inspection of the Sydney TMY2 weather data revealed an annual average wind speed of 5 m/s.

2. Conclusion

The PVT and building energy modelling and simulation shows promising potential for PVT systems to be integrated into well insulated residential houses in the Sydney climate. The results presented in this paper illustrate that a covered PVT system could feasibly provide adequate thermal comfort for occupants while also achieving the aims of eliminating the need for heaters, increasing the electrical output from the photovoltaic system and further reducing the energy requirement of the household. Further investigations into the pressure drops and required fan power to operate the PVT system and also the use of the building integrated PVT system with an air/earth heat exchanger for both winter heating and summer cooling will continue on from this work.

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