Solar on the roof with EV batteries could meet the majority of Japan’s Power
A new analysis from the University of Tohoku shows that combining solar panels on the roof with battery storage of electric vehicles up to 85% of Japan’s electricity needs could be satisfactory and at the same time cut the carbon emissions by 87%. The study underlines a practical path for the local authorities of Japan to reach CO2 neutrality using existing roofs and vehicles instead of investing in expansive centralized systems.
With limited land and growing demand for clean energy, Japan stands for unique limitations. Yet his vast area on the roof of 8,000 km2 and a rapidly expanding EV fleet offers unused potential. The integrated system, called “PV + EV” or “Solarev City”, offers both environmental and economic benefits, making municipalities self-dependent.
Researchers performed a detailed techno-economic analysis of all 1,741 municipalities in Japan. Based on 70% roof coverage with 20% efficiency solar panels and EVs equipped with 40 kWh batteries (half used for griders services), the team that only PV could only be produced on the roof found 1,017 TWH-Exchants of the 2022 electricity output of Japan annually. On average, solar zon on the roof could supply 45% of the local electricity, but the integration of EV batteries increased to 85%. Moreover, the system could lower the energy costs by 33% by 2030.
The study found a strong potential in both national and urban areas. Rural regions can generate much more electricity than they consume, while despite spatial limits, cities such as Tokyo can improve grid stability with the help of EV -battery integration. The system also improves peak demand management and reduces dependence on fossil fuels.
“To realize this system and go to a greener society, we need policy support at the end of the day,” said Takuro Kobayashi of the University of Tohoku. The research is intended to inform the policy by emphasizing regional potentials and challenges.
The most important policy reasons include stimulating support for vehicle-to-home (V2H) and Vehicle-TOT-GRID (V2G) technologies, tackling energy-specific capacity in low-solution areas and increasing public consciousness. The current subsidies from Japan for EVs and PVs on the roof are a basis, but further investments are crucial to enable full system integration.
Research report:On the carbon tube potentials of PVs on the roof integrated with EVs as a battery for all municipalities of Japan
