Multi-objective and multi-parameter optimization of solar domestic hot-water systems for reducing on-peak power consumption

Solar Domestic Hot-Water Systems can be a useful tool to reduce the energy consumption and on-peak power demand. This is particularly important in the case of Brazil where water heating in most cases is done using electrical showerheads with high installed power and low load factor. Consumers and utility companies have conflicting interests: reducing the electricity bill and shave the on-peak consumption. In the present work, these two interests were weighted and put together in the same objective function in order to find the trade-off curve with the optimized design parameters (collector area, storage volume and set point temperature) of the solar system. The analysis is carry out by considering two different policies: rebate program and time-of-use tariff (TOU). The results of the first policy show the existence of a trade-off curve between the initial investment and the yearly electricity consumption, which can be used to size the monetary incentive used for rebating the initial cost of the SDHW system. On the other hand, the results of the second policy shows a trade-off curve between the annualized life cycle cost of the system and the yearly on-peak electricity consumption, which can be used to size the TOU tariff as a function of the commitment of the utility company on reducing the on-peak electricity consumption.