Solar driven water heating systems for medium-rise residential buildings in urban mediterranean areas

Abstract

International Energy Agency reported that buildings are accountable for one-third of the global final energy demand in 2017. On-site renewable energy generation can reduce buildings' grid electricity consumptions. Medium-rise buildings located in urban areas have limited available rooftop or facade surfaces, thus solar driven technologies such as solar thermal, photovoltaics (PV) or photovoltaics/thermal (PV/T) are in competition for the available space. This investigation aims to compare available solar driven water heating systems in the market, suitable to replace the conventional electric water heater for a multi-residential building. Under the present study, solar PV electric water heating system (S1), solar thermal water heating system with electric boosting (S2), solar PV/T water heating system with electric boosting (S3) and integrated solar PV and heat pump water heating system (S4) are investigated. The performance parameters compared are the annual net electricity consumption from the grid and the net present value of life-cycle cost (LCC) for 20 years life. Results reveal that S3 and S4 have ‘net’ positive electricity production but higher initial costs, compared to the other systems. For buildings located in colder climates, S2 has lower LCC compared to S3 but for warmer climates the LCC of S3 is the lowest.