Economic optimization and comparative study of solar heat pumps

In this paper, an economic study of solar heat pumps and an investigation of differences between solar heat pumps and conventional heat pumps—based on their performances and energy consumption—are conducted for a residential apartment located in Austin, Texas, USA. Heating in the apartment is provided via a solar heat pump during the cold months of a year. Solar collectors are used to meet the domestic hot water requirement of the apartment during the other months. In order to carry out a rational comparison, the base system comes with an air-to-air domestic heat pump and a boiler to provide domestic hot water. The comparison includes both energy consumption (fuel and power) and economic aspects. The simulation is performed through the commercial software TRNSYS, in which optimization offers a collectors’ surface of 28 square meters. The proposed configuration requires almost half of the electrical energy that the conventional system consumes. Its fuel consumption is about a quarter of the non-solar system, which offers a double value of COP in comparison with the traditional system. The economic calculations reveal that the payback period is about two years.