ENERGY METERING OF SOLAR DOMESTIC HOT WATER SYSTEMS FOR INCLUSION IN GREEN POWER AND RENEWABLE PORTFOLIO STANDARD PROGRAMS

摘要

There are several reasons Solar Domestic Hot Water (SDHW) systems are not yet included in production based programs, but perhaps the most important is the lack of an agreed upon metering methodology. In this study, a drain-down SDHW system fitted with energy meters was monitored in both summer and winter. Two thermal energy meters (Btu meters) metered the energy sent to the house in the form of hot water and the energy collected by the solar system. TRNSYS simulations indicated that the hot water load, as measured with a thermal meter, minus the electric energy input, as measured by an electric meter, plus the amount of energy lost by the tank (based on a standard experimental daily loss) is equal to the amount of energy offset by the use of the solar system. Even with extreme hot water draw profiles, this methodology worked exceptionally well for metering the amount of electric energy offset by the solar energy gain.