Future office buildings are expected to be integrated with energy intensive, inherently DC components such as photovoltaic panels (PV), electric vehicles (EV), LED lighting, and battery storage. This paper conceptualizes the interconnection of these components through a 750 V DC nanogrid as against a conventional three-phase 400 V AC system. The factors influencing the performance of a DC-based nanogrid are identified and a comparative analysis with respect to a conventional AC nanogrid is presented in terms of efficiency, stability, and protection. It is proved how the minimization of grid energy exchange through power management is a vital system design choice. Secondly, the trade-off between stability, protection, and cost for sizing of the DC buffer capacitors is explored. The transient system response to different fault conditions for both AC and DC nanogrid is investigated. Finally the differences between the two systems in terms of various safety aspects are highlighted.

The paper provides a comparison of four PV-battery architectures with dc and ac backbones, in terms of autarky, energy efficiency, battery size and reduction of annual electricity cost. The comparison is conducted based on the residential load and irradiation data from the Netherlands. The effect of different PV generation is also analyzed by comparing the results with irradiation data from Costa Rica. The results show that the ac coupled architecture gives the best performance.