Japan’s renewable-energy transition is shaped by high energy-import dependence, limited flat land, mountainous terrain, densely populated cities and deep surrounding seas. The country has already built one of the world’s largest solar markets, but the easiest phase of deployment is ending. Future growth must come from a more complex mix of rooftop and next-generation solar, offshore wind, upgraded hydropower, geothermal development, biomass and a stronger national grid.
Renewables accounted for 22.9% of Japan’s electricity generation in fiscal year 2023. The Seventh Strategic Energy Plan, approved in 2025, raises the long-term ambition considerably: renewables are expected to supply 40% to 50% of electricity in fiscal year 2040. Achieving that range will require more than repeating the policies that drove the first solar boom. Japan must now solve problems of location, cost, grid congestion and local consent.
Solar Built the First Stage, but Available Land Is Tightening
Solar power became Japan’s leading modern renewable source after the feed-in tariff introduced in 2012 created a strong investment market. By fiscal year 2023, solar supplied about 9.8% of the national electricity mix. Japan now has one of the highest levels of photovoltaic capacity per unit of land among major economies.
That success has created a new constraint. Easily developed flat land is becoming scarce, while some projects built on slopes have raised concerns about drainage, landslides, landscape damage and weak consultation with nearby communities. Solar remains central to national plans, but its physical form must change.
The 2040 outlook expects solar to provide 23% to 29% of electricity. Rooftops, factories, logistics facilities, public buildings, car parks and other built surfaces will therefore become more important. Corporate power-purchase agreements can also support projects outside the traditional subsidy system by connecting renewable generation directly to long-term commercial demand.
Japan is placing particular emphasis on perovskite solar cells. These cells can be lighter and more flexible than conventional silicon panels, allowing installation on walls, curved surfaces and roofs that cannot support heavy equipment. The technology also has an industrial-policy attraction because iodine, an important input, is available domestically. Government-backed work aims to move perovskite technology toward practical use before 2030.
Repowering older sites, improving panel efficiency and pairing projects with batteries can also raise output from existing locations. The next solar market will be more urban, distributed and technology-intensive than the land-based expansion of the previous decade.
Offshore Wind Is Japan’s Largest Untapped Power Opportunity
Wind supplied only about 1.1% of Japan’s electricity in fiscal year 2023. The government wants wind’s share to rise to 4%–8% by 2040, with offshore development carrying much of that increase.
Japan’s offshore wind strategy targets 10 GW of projects by 2030 and 30–45 GW by 2040. By the end of 2024, around 5.1 GW of projects were under development. Ports in Akita and other coastal regions have begun supporting early commercial activity, while a national zoning and auction system gives developers a route to secure long-term use of designated sea areas.
The industrial opportunity extends beyond electricity. Offshore wind requires foundations, floating platforms, towers, cables, ports, maintenance vessels and engineering services. Japan could use its experience in heavy industry, shipbuilding and marine engineering to build a domestic supply chain.
Yet the sector faces serious delivery risks. Japan has no domestic manufacturer of the largest modern offshore turbines, leaving projects exposed to foreign suppliers and global equipment costs. Inflation and higher financing costs have weakened project economics. Fishing rights require detailed negotiation, while typhoons, earthquakes and difficult seabed conditions raise technical standards.
Deep coastal waters also limit areas suitable for fixed-bottom turbines. Floating offshore wind may therefore be necessary for large-scale development. Floating systems can reach stronger winds farther from shore, but costs must fall and mass-production methods must mature. Delivery will depend on auction design, bankable prices, port investment, grid access and local participation.
Geothermal Potential Meets Hot-Spring and Conservation Concerns
Japan sits on one of the world’s most active volcanic regions and has substantial geothermal resources. Geothermal power can operate continuously, making it valuable in a system with rising solar and wind generation. Despite this potential, it supplies only a small part of national electricity.
Development is slow because promising resources are often located near national parks, protected landscapes or hot-spring communities. Onsen operators may fear that drilling could affect water temperature or flow. Exploration is also expensive and uncertain because companies may drill without finding a commercially useful resource.
The government plans to use the Japan Organization for Metals and Energy Security to lead or support surveys that reduce early-stage risk. New drilling methods may eventually broaden the number of usable sites. However, projects also need credible monitoring, transparent data and long-term agreements with local governments and hot-spring businesses.
Hydropower faces a different form of maturity. Japan already has a large fleet, and opportunities for major new dams are limited. The most realistic gains may come from modernising turbines, improving control systems and adding capacity at existing facilities. Pumped-storage plants can also help balance variable output.
A Fragmented Grid Limits the Value of Renewable Resources
Japan’s best renewable resources are not always near its largest centres of demand. Hokkaido and Tohoku have strong wind potential, while Tokyo, Nagoya and Osaka account for major electricity consumption. Moving power between these regions remains difficult because the national system developed through separate regional utilities with limited interconnection.
Japan also operates two electricity frequencies: 50 hertz in the east and 60 hertz in the west. Frequency-converter capacity has increased, but this division still complicates nationwide balancing.
The planned reinforcement of the Hokkaido–Honshu connection is especially important. High-voltage direct-current links can carry northern wind power toward larger markets on Honshu. Wider upgrades between Tohoku and Tokyo, and between other regional systems, are also necessary.
Without stronger transmission, curtailment will rise. Solar-rich regions can produce more electricity than local demand during sunny, low-consumption periods. Batteries, pumped storage and demand response can reduce waste, but they cannot fully replace long-distance transmission. Grid construction must therefore become part of renewable policy rather than a separate infrastructure issue.
Support Is Moving from Rapid Expansion to Market Discipline
Japan’s feed-in tariff successfully created a large renewable market, but it also locked in high purchase prices and contributed to a surcharge on electricity consumers. The renewable surcharge reached 3.98 yen per kilowatt-hour in fiscal year 2025. The government is now trying to reduce costs through competitive tenders, the Feed-in Premium system and projects that sell more directly into the market.
Authorities have also acted against approved projects that failed to begin operation. Around 80,000 FIT or FIP certifications had been invalidated by late 2025. New rules place greater emphasis on legal compliance, community meetings, safety and equipment disposal.
This shift matters because public acceptance is becoming a scarce resource. Poorly planned solar sites, weak explanations to residents or uncertainty over end-of-life waste can create resistance that affects the entire industry. Offshore wind and geothermal projects face similar risks if communities see national targets but few local benefits.
Japan’s renewable expansion will be strongest where projects are linked to regional development, local revenue, jobs and disaster resilience. Its 2040 path will not be dominated by one technology. Solar must move onto buildings and advanced surfaces, offshore wind must become commercially deliverable, geothermal must earn local trust, and the grid must connect remote resources to urban demand. Success will depend on whether Japan can turn its engineering strengths into projects that are affordable, connected and accepted where they are built.
