Analysis of a roof-top combined photovoltaic / solar thermal plant at Christchurch

Abstract

[Abstract]: This paper presents an economic perspective of rooftop solar systems consisting of a 1kWp grid-connected photovoltaic (GC-PV) and an evacuated tube solar collector (ETC) water heater (1.37m2 unit) as a case study at Christchurch, New Zealand. The study considers the case that both systems are partially covering the energy demand of a one-family house. According to the average availability of solar radiation at Christchurch the expected year ac energy yield of the 1kWp GC-PV system has been found to be 1018 kWh/year and that of the solar thermal collector 851 kWh/year. Economic analysis has been carried out on the basis that PV electricity is fully used, either directly at user premises or by feeding the utility grid whereas the thermal energy made available by the solar collector is assisting the usual electrical water heating system to supply the necessary hotwater demand. The assumption made in this analysis is that the energy provided by the solar water heater is entirely replacing the otherwise used electricity for heating water. The final electrical energy demand after installing the solar system is then calculated. The presented analysis can be applied for larger capacities for commercial and industrial users considering that repetitive units of the here presented modules can be considered.