Feasibility study of using domestic solar hot water systems as alternative to reduce the electricity peak demand in Brazil

摘要

Brazil is one of the few countries where the water heating for bath is performed by using electric showerheads. The widespread use of these devices is the mainly responsible for the high peak on the electricity demand of the residential sector, observed between 18:00 and 21:00 hours. As a consequence of that, costs and service quality are undermined, affecting consumers and the electricity sector in general. In attempt to deal with this issue, solar hot water systems have been proposed as an option to reduce the electricity consumption of the showerheads. However, despite of the high incidence of solar radiation on the Brazilian territory indicates a significant economy, currently there is no technical assessment quantifying the economic benefits on the region. The present study estimates the economic impacts resulting by the deployment of solar hot water systems in Brazilian households. Hence, the feasibility study allows assessing the potential of solar water heating as alternative to reduce the peak on the electricity demand in Brazil. In order to perform the proposed analysis, long-term performance simulations were performed on an hourly basis using the TRNSYS software as computational tool and typical meteorological year (TMY) files as input data. The TRNSYS component (Type 45) relating the solar water heating equipment had been experimentally validated, whereas the weather data was obtained from the SWERA database. Also, a time dependent profile of the heating demand is considered, according the measurements collected in previous studies. The thermal performance is evaluated in terms of solar fraction. On the other hand, the economic impacts are quantified in terms of three criteria for economic feasibility, such as payback period, internal rate of return and life cycle savings. In order to explore the benefits arising from different policies, four tariff scenarios are considered. The economic evaluation is positive over all scenarios analyzed, showing savings for both, the consumers and the electricity sector. The results of this analysis can be used as support tool for target setting the adoption or spread the use solar water heaters, or even to create policies for its diffusion.