Simulation and Performance Analysis of a Solar Domestic Hot Water System Controlled by Weather Forecast Information

Abstract

The main goal of the present paper is to propose the use of a two-reservoir solar domestic hot water system (SDHWS), to reduce the electric energy peak due to the extensive use of electric showerheads (ESH) in dwelling. The proposed SDHWS is designed for low-income dwelling in Brazil. The electric energy demand profile due to these houses are obtained from data collected from a fully monitored sample of ninety houses, in the frame of a two years long experiment reported in previous papers. The SDHWS is designed with the help of software TRNSYS, by using typical meteorological year (TMY) data available for Brazilian capital cities. The TMY data is available at the SWERA database. The TMY data are modified so that the meteorological data profile of any day is used as the forecast data for the day after. The auxiliary energy is supplied to a backup tank in the early hours of the day whenever the solar radiation distribution is expected to have low availability for the solar system. The backup tank volume is optimized in order to get the maximum reduction of the electric energy peak. The paper reports characteristic plots of the frequency of days the energy peak demand in the critical time between 6:00PM and 9:00PM is required, against the energy peak reduction fraction, for different overloads in comparison to a reference fixed load distribution.