Rooftop solar and EV batteries could supply 85% of Japan’s electricity needs

A brand new examine led by Tohoku College has revealed that rooftop photo voltaic panels, when mixed with electrical autos (EVs) as batteries, might provide 85% of Japan’s electrical energy demand and cut back carbon dioxide emissions by 87%. The analysis offers a promising pathway for Japan’s native governments to realize carbon neutrality by making the most of current infrastructure—rooftops and autos—moderately than relying solely on large-scale vitality programs.

Because the urgency of local weather change accelerates, cities and municipalities world wide are exploring methods to decarbonize their energy systems to decelerate these modifications. Japan, with its mountainous terrain and restricted out there land for photo voltaic farms, faces distinctive challenges. Nevertheless, the nation has greater than 8,000 km² of rooftops and a quickly rising EV market.

The mix of rooftop photovoltaic (PV) programs and EV batteries—known as the “PV + EV” system or “SolarEV City”—provides a sensible and cost-effective resolution to assist transition to renewable vitality and vitality self-sufficiency.

The examine, published in Utilized Vitalityaimed to reply three important questions: What’s the decarbonization potential of PV + EV programs throughout all municipalities in Japan? What regional elements affect their effectiveness? How can these findings inform nationwide and native vitality coverage?

To seek out solutions, the analysis crew carried out a complete techno-economic evaluation for all 1,741 municipalities in Japan. They assumed that 70% of rooftops could be fitted with 20%-efficiency PV panels, and that EVs with 40 kWh batteries would function family storage, utilizing about half their battery capability for grid flexibility.

Their findings had been placing: rooftop PV might generate 1,017 TWh yearly—greater than Japan’s complete electrical energy era in 2022. On common, a PV-only system might provide 45% of municipal electrical energy wants, whereas the PV + EV system boosted this determine to 85%.

Along with drastically lowering CO₂ emissions from each electrical energy and driving, the system might decrease vitality prices by 33% by 2030.

These outcomes carry broad implications not just for Japan, however for nations worldwide that face related constraints. Rooftop PV + EV programs are significantly promising for city and rural areas the place centralized renewable vitality programs might not be possible.

In rural areasthe examine discovered that some municipalities might generate a number of instances their electrical energy demand by way of rooftop PV alone. Whereas extremely urbanized areas like Tokyo face better limitations resulting from smaller rooftop areas and fewer autos, they nonetheless profit from the combination of EV batteries to extend vitality flexibility and cut back peak demand.

“To make this system a reality and move toward a greener society, we need policy support at the end of the day,” remarks Takuro Kobayashi from Tohoku College. “A major goal of this study was to provide a wealth of scientific information that policymakers can refer to when making decisions about implementation.”

When making these insurance policies, there are lots of elements to think about. Policymakers should handle regional disparities, particularly for northern areas with decrease photo voltaic potential, the place vitality poverty could possibly be exacerbated throughout the transition interval. Moreover, whereas Japan at present provides subsidies for EVs and rooftop PV programs, stronger help is required for bidirectional charging infrastructure (V2H and V2G), battery integration applied sciences, and public consciousness. This analysis exploring the potential of PV + EV programs is an important step nearer towards decarbonization.

The analysis was led by Tohoku College in collaboration with the College of Tokyo, the Nationwide Institute for Environmental Research, Radboud College (Netherlands), and the Meteorological Analysis Institute.