Abstract:
The auxiliary requirement of a solar water heating system is an index of the end-user's cost and, thus, the feasibility of the system. Within this study several locations worldwide with high and low solar radiations and electricity prices in latitudes of 0, 15, 30, 45 and 60°N have been selected and the effect of employing a Compound Parabolic Collector (CPC) on the yearly auxiliary energy saving of a solar water heating system has been investigated numerically and compared with the energy performance of a typical flat plat collector. The yearly solar radiation in selected locations ranges from 2509 to 852 kWh/m2. Electricity prices also vary from 0.04 to 0.28 USD/kWh. According to results, in all selected locations, CPC shows an advantage over flat plate collectors in auxiliary power consumption. The yearly auxiliary heating rate decreased maximum by 27% in Shambat in Sudan and minimum by 5% in Chongqing in China. As solar radiation increases, the advantage of CPC becomes more meaningful. Regarding costs and economic feasibility of CPC, maximum net present values are all achieved in the locations with the highest electricity prices and not very high discount rates. Selected locations in Japan and Italy with maximum NPV values of 1,981 and 1,811 UDS, respectively, have the highest electricity rates of 0.28 and 0.27 USD/kWh, in respect. In both countries, the discount rate is relatively low and about 0.3. Moreover, among the selected locations, NPV of investment on CPC in Gabon, Guatemala, USA, Japan and Sweden with low levels of solar radiation, between 974 and 1,942 kWh/m2, is between 832 and 1,981 USD at the end of the project’s life time and justifies the employment of this type of solar collector in sites with high energy prices, even though not much solar radiation is available. It could be concluded that in locations with high electricity prices and not very much discount rates, even in cases of relatively low solar radiation, investment in CPC would yield the highest profits.
