Optimization of renewable energy for buildings with energy storages and 15-minute power balance

Abstract

When planning renewable hybrid energy solutions in buildings, it is important to consider both investment and operating costs. This study develops a novel building optimization model based on the coming 15 min power balance settlement. It utilizes multiple energy storages, including hot water tank and flow and lead-acid batteries. We apply the model to plan the retrofitting of an office building in Helsinki and a residential building in Tallinn, with photovoltaics and a ground source heat pump. The model is a large dynamic linear or mixed-integer linear programming model (LP/MILP) for an entire year. The results determine both the optimal dimensioning and the optimal operation of the different production and storage technologies for each building. The optimized configurations caused significant savings in energy costs for both buildings while reducing non-renewable primary energy consumption. Heat storage is highly cost-efficient, but power storages are not. Photovoltaics is cost-efficient in the Helsinki building but slightly unprofitable in the Tallinn building. Power and heat storages do not interact strongly, even in the presence of the ground source heat pump. The heat storage operates in concert with district heating and the ground source heat pump, while power storages operate together with photovoltaics and power trade.