Economic and environmental life cycle analysis of solar hot water systems in the United States

This paper evaluates the solar water heating systems for the U.S. typical residential buildings, from the energetic, economic and environmental perspectives, and includes two different types of solar collectors (i.e. flat-plate and evacuated-tube solar collectors), two types of auxiliary systems (i.e. natural gas and electricity), and three different locations (i.e. Los Angeles, Atlanta, and Chicago). The performance of solar water heating systems is also compared with conventional systems that use either natural gas or electricity. The results showed that the flat-plate solar water heating systems using natural gas auxiliary heater has the best performance among all the types and at all locations. The energetic and environmental payback periods for solar water heating systems are less than half of a year, and the life cycle cost payback for solar water heating systems vary from 4 to 13 years for different cities and different configurations when using the conventional electrical water heating system in each city as the benchmark. For a representative case, i.e. flat-plate solar water heating system with natural gas auxiliary heater in Atlanta, sensitivity analysis shows that the daily hot water use has the most significant effects on energetic, environmental and economic performance.

► This manuscript compares water heating systems with different solar collectors and auxiliary fuels.
► This study examines the energy, economic and environmental performances of the water heating systems.
► The comparison was conducted in three locations in the U.S.: Los Angeles, Atlanta, and Chicago.
► Natural gas fired flat-plate system has the best performance among all options.
► The daily hot water use is the most sensitive parameter for the life cycle analysis.