Application of a Calibrated Building Energy Model for the optimal sizing of a photovoltaic plant: An approach from self-consumption

In the context of the decarbonization transition, the use of building-integrated photovoltaic systems has become a popular strategy. A critical challenge to be faced when designing them is their adequate sizing. A feasible approach to address this issue is to ensure that the photovoltaic plant provides the maximum possible autonomy to the building, covering its energy needs but without producing large surpluses that are fed into the grid. In essence, the objective of that approach, which is explored in this study, consists of sizing the building integrated photovoltaic system to achieve the highest levels of self-consumption and self-sufficiency. To illustrate this sizing methodology, an in-depth analysis on a real building located in Lavrio, Greece, is conducted, employing a calibrated Building Energy Model. The analyzed data corresponds to the building operation during 2019. First, this study assesses the impact that models with different levels of calibration have within the proposed PV plant sizing approach. Results indicate that non or partially calibrated building energy models differ significantly from reality. Then, based on the fully calibrated model, the optimal plant for the case-study is analyzed. In this particular test-site, the actual photovoltaic plant is significantly undersized to meet the building's energy needs. Finally, leveraging the calibrated building energy model, a straightforward optimization strategy that involves storing excess photovoltaic production in the building's thermal mass is implemented, which leads to an interesting increase in self-consumption and self-sufficiency. This approach not only determines the appropriate size for the photovoltaic system but also maximizes its operational efficiency.