ABSTRACT
This chapter introduces a Microsoft Excel program which predicts the savings and payback period for domestic hot water solar systems. This program is in the Microsoft Excel file, Domestic Hot Water. There are several variations of solar hot water systems. For cold weather locations, either non-toxic antifreezes are used for the collectors’ working fluid, or the systems are set up to drain the water from the collector when the fluid temperature approaches freezing. This latter approach is called a drain back system. Monthly weather data used in the program include the average daytime temperature, the percent of possible sunshine, and the atmospheric clearness number of the location being analysed. The weather data are given in the Microsoft Excel file Weather Data-F. The chapter discusses an overall approach for estimating the energy cost savings realized from a solar domestic hot water system.
