Electrical system architectures for building-integrated photovoltaics: A comparative analysis using a modelling framework in Modelica

Building integrated photovoltaic (BIPV) systems may be catalyzers of sustainable, near-zero energy buildings. To maximize the benefits of employing BIPV, it is important to integrate them properly into the grid of the building. The discussion on AC versus DC distribution for microgrid and nanogrid backbones is currently revisited as the level of penetration of renewable sources, electric vehicles and DC loads is constantly increasing. This paper tackles this question and provides guidelines using a validated simulation framework. The study compares DC (48 V and 380 V) and AC (230 V/50 Hz) topologies integrated into a ten-story office building with façade-integrated BIPV. Annual simulations are carried out for five locations with different climatic conditions and comparisons are made in terms of system- and component-level efficiency, system losses, self-sufficiency, self-consumption and CO2 emission. The analysis shows that the DC topologies perform better than the AC one, especially for the locations with high solar energy yield compared to the cooling and heating loads. Further, a parametric analysis is performed to determine the optimal sizing of the building grid components, DC and AC alike. Finally, different scenarios of battery energy storage system capacity are examined in order to test the sensitivity of the performed analysis.