There are several options of renewable energy systems available in the market, in this study were considered the solar thermal (ST) and the photovoltaic (PV) systems. This two system were adopted, since they have shown to be effective in urban environments, special in southern european climates, where sun irradiation is high.

DHW represents a significant share of the overall energy demand, making it a preferential target for renewable energy use. Thus, a solar thermal system is used to supply the DHW. In adition we also considered the use of solar thermal to supply hot water to the washing machines (MHW) and the heating needs of the house. The auxiliary energy of the ST and the cooling (and heating in some scenarios) needs are supplied by a heat pump with an average COP of 2.5.The PV system is sized so that it supplies all the electric needs of the house, including the electricity needs of the heat pump on a net yearly basis.

2.3 Solar thermal system

The solar thermal system is composed by: a reservoir and a set of solar thermal panels with 50° inclination facing south, as discussed, a heat pump provides the auxiliary energy, needed to maintain the water in the reservoir above 43°C. The inclination of the thermal solar panels was optimized using the simulation software EnergyPlus. When the water in the reservoir reaches very high temperatures (80°C) a heat rejection system is used.