Renewable energy (RE), hybrid electric vehicles (HEVs), and electric vehicles (EVs) are expected to become increasingly widespread alongside efforts toward carbon neutrality. In Japan, photovoltaic (PV) power is the most widely deployed RE source, but its output is highly dependent on weather and exhibits significant short-term fluctuations. The target region of this study, Hokkaido, is Japan’s northernmost prefecture, characterized by vast land, cold climate, and extensive dairy farming. As a result, biogas (BG) generation using fermented cattle manure is widely adopted; however, BG output cannot be flexibly adjusted in the short term and is generally used as a baseload power source. Combining highly variable RE with power sources that have limited adjustability makes it difficult to maintain a supply-demand balance. Introducing microgrids in small regions and integrating RE with batteries is an effective solution to stabilize supply and demand. However, in kW-scale systems, deploying new batteries remains economically challenging.

The authors have previously proposed an emergency-oriented microgrid model that utilizes EVs as virtual power lines and combines reused EV batteries with RE to stabilize power supply. However, the application of such systems for normal daily operation has not been sufficiently investigated.

In this study, an extended microgrid model for daily operation was developed based on the previous emergency-oriented model, targeting a small municipality in Hokkaido. The microgrid integrates PV and BG generation and includes a V2X system to provide supply-demand regulation.

To construct EV operation patterns, municipal gasoline vehicles and EVs were equipped with GPS loggers to collect multi-day driving and parking data. Two consecutive EV operation patterns with different driving and parking behaviors were employed to design the V2X control strategy.

The microgrid load consists of three public facilities—a hospital, a welfare center, and a town hall—assumed to be connected via the municipality’s distribution network. The V2X system comprises five EVs and stationary batteries utilizing reused lithium-ion batteries (LIBs) from EVs, with capacities of 62 kWh and 59 kWh, respectively. Under V2X control, the EVs and LIBs perform charge-discharge operations to maintain supply-demand balance, with power exchange with the commercial grid if additional regulation is needed. In addition, high-output reused nickel–metal hydride batteries (Ni-MH) from HEVs, with a capacity of 8.7 kWh, are installed on the PV side to smooth short-term PV output fluctuations and supply a combined output to the microgrid.

Simulations using MATLAB/Simulink over five weekdays were conducted to evaluate the RE utilization ratio. The results confirmed that the RE utilization ratio exceeded 99.9% for both EV operation patterns. These findings demonstrate that the V2X system can effectively coordinate EV and LIB operation to stabilize the microgrid’s supply-demand balance under normal daily conditions.