A general sizing methodology of grid-connected PV systems to meet the zero-energy goal in buildings

Abstract

This work expresses the most general definition of zero-energy building through a set of equations based on measured energy consumption and electricity generation predictions. This helps determining the optimal size of grid-connected photovoltaic systems for upgrading any highly efficient or conventional building into a zero-energy building. Opposed to previous works, which consider only electrical consumptions, this article includes consumption from fossil fuels and district heat and cooling networks. The study also covers environmental parameters and an economic study adaptable to any electricity market structure, contributing to deciding the best electricity tariff to hire.The methodology was applied to passive and conventional single-family houses in Spain. Results showed that the performance of a grid-connected photovoltaic system depends critically on the energy sources imported by the building. In particular, the performance improves in buildings where the electricity represents most of the imported energy. The required minimum size of the photovoltaic system in the conventional house (14 kWp) is far greater than in the passive house (9 kWp). After the recent global increase in electricity prices, annual economic savings of 70.12 % and 49.71 %, and payback periods of 6 and 13 years for the passive and conventional houses, respectively, make the investment profitable.