Techno-economic Analysis Of Residential Solar Water Heaters In South China

Solar energy has the advantages of popularization, environmental friendly and sustainable for uitilization. Solar energy utilization is the important contents of sustainable development and the mainly technology means of improving energy consumption structure in many countries. In addition, the energy consumption of residential hot water in China is far lower than that in developed countries, and the level in rural is lower than that in town. With the constantly raising of people's living standard, water heater is becoming a necessity for most families, and the hot water demand will keep rising.Based on the viewpoint of energy saving, environmental protection and sustainable development, it is necessary to popularize the use of solar water hater. In comparison with conventional water heaters, the competitiveness of solar water heater depends mainly on its techno-economy. In this paper, for the hot water supply in a typical residential building with three people, the thermal performance of natural circulation solar water heaters in South China which has relatively poor solar energy resource has been hourly simulated based on hourly meteorological data of typical meteorological years, then a techno-economic analysis of solar water heater is conducted. Research results have provided important reference for optimizing the design of solar water heater, improving energy saving, popularizing the use of solar water hater, along with guiding the technical progress and market development of water heaters. The specific contents include the following work:(1) Based on hourly meteorological data of typical meteorological years in Fuzhou, the thermal performance of flat plate solar water heater has been hourly simulated. The effect of collector area and the instantaneous efficiency curve of collector on the thermal performance and economy of flat plate solar water heater are analyzed. An economic comparison between flat plate solar water heater and conventional water heaters is conducted; also the effect of energy price system on the economy of different types of water heaters is discussed. The results show that under the current energy price system, for flat plate solar water heater, the minimum present value of synthetic energy price of 0.283 RMB/(kWh) has been obtained when the collector area is 4 m2, with the annual average solar fraction of 62.25%. Flat plate solar water heater has great synthesized competitiveness, and its present value of synthetic price is significantly lower than that of conventional water heaters. In addition, it can be seen that with the increase of energy price, the economic superiority of solar water heater is more significant.(2) Based on hourly meteorological data of typical meteorological years in Fuzhou, the thermal performance of flat plate and all-glass evaculated tube solar water heater has been hourly simulated. The effect of collector area on the economy of all-glass evaculated tube solar water heater is analyzed,also an economic comparison between flat plate and all-glass evaculated tube solar water heaters is discussed. The results show that under the current energy price system, for all-glass evaculated tube solar water heater, the minimum present value of synthetic energy price of 0.330 RMB/kWh has been obtained when the collector area is 3 m2, with the annual average solar fraction of 61.81%. In comparison with all-glass evaculated solar water heater, flat plate solar water heater has more competitiveness, but in comparison with conventional water heaters, all-glass evaculated solar water heater has good economic superiority.(3) Based on hourly meteorological data of typical meteorological years in forteen cities in South China, the thermal performance of flat plate solar water heaters has been hourly simulated. An economic comparison of the thermal performance and economy of flat plate solar water heater in different cities is conducted. The results show that flat plate solar water heater has good thermal performance and economic potential in Southern China. Under the current energy price system, when the collector area is 4.0 m2, the annual average solar fractions are over 50% and the minimum present values of synthetic energy price are obtained at almost all over Southern China.(4) Based on above analysis, by converting the annual energy consumption of different types of water heaters to standard coal (primary energy consumption), a comparison of the energy saving and environmental benefit of solar water heater and conventional water heaters in Fuzhou is conducted. The results show that solar water heater has significant energy saving and environmental benefits.