Optimization model for evaluating on-site renewable technologies with storage in zero/nearly zero energy buildings

This study develops, tests and applies an optimization model to evaluate on-site renewable energy technologies with storage in buildings and assess optimal configurations for zero or nearly zero energy buildings. The proposed model is a single-objective hourly-basis mixed integer linear programing model developed in GAMS and solved by CPLEX. The model considers the rooftop availability for installing solar PV and mini wind turbines and the available volume constraint for installing battery. It was tested for different assumptions of electricity prices in a virtual case. Then, a case study for a real building in Portugal was performed, according to scenarios taking into account the current grid-electricity tariffs. Feed-in tariffs in different schemes were also analyzed, as well as the cost evolution of the technologies and the implementation of a bi-hourly tariff. Findings show that the developed model is suitable to evaluate options to implement zero or near zero energy buildings (nZEB), based on renewable technologies. However, for nZEB become competitive, some conditions should be met, especially in terms of the price differentials between the tariffs to purchase electricity from the grid and sell it back.