This work presents a comparison of alternating current (AC) and direct current (DC) distribution systems for a residential building equipped with solar photovoltaic (PV) generation and battery storage. Using measured PV and load data from a residential building in Sweden, the study evaluated the annual losses, PV utilization, and energy savings of the two topologies. The analysis considered the load-dependent efficiency characteristics of power electronic converters (PECs) and battery storage to account for variations in operating conditions. The results show that DC distribution, coupled with PV generation and battery storage, offered significant loss savings due to lower conversion losses than the AC case. Assuming fixed efficiency for conversion gave a 34% yearly loss discrepancy compared with the case of implementing load-dependent losses. The results also highlight the effect on annual system losses of adding PV and battery storage of varying sizes. A yearly loss reduction of 15.8% was achieved with DC operation for the studied residential building when adding PV and battery storage. Additionally, the analysis of daily and seasonal variations in performance revealed under what circumstances DC could outperform AC and how the magnitude of the savings could vary with time.

This paper simulates the impact of battery sizing for an actual nearly-zero energy (NZEB) single-family house with solar PV located in Boras, Sweden. Simulations are done,° using measurement data as an input, for three different battery dispatch algorithms with two different purposes; (i) peak power shaving and (ii) maximising system self-consumption (SC) and self-sufficiency (SS) of the solar PV. The results show that the optimal battery storage size for this single-family house, given its measured electrical loads and existing solar PV system is around 7.2 kWh. System self-consumption and self-sufficiency from generated solar PV increased with 24.3 percentage points compared to a reference case without battery. Furthermore, results show that increasing the battery size beyond 7.2 kWh only results in minor performance gains.

In this paper, the performance of a direct current (DC) distribution system is modelled for a single‐family residential building and compared with a conventional alternating current (AC) system to quantify the potential energy savings and gains in photovoltaic (PV) utilisation. The modelling is made for two different climates to quantify the impact of the geographical location. Results show that the system losses are reduced by 19–46% and the PV utilisation increased by 3.9–7.4% when using a DC distribution system compared to an AC equivalent, resulting in system efficiency gains in the range of 1.3–8.8%. Furthermore, it is shown that the geographical location has some effect on the system's performance and PV utilisation, but most importantly, the grid interaction is paramount for the performance of the DC topology.