Solar panels in Tokyo

Modelled output of a 6 kWp system at 35° facing south (towards the equator), from PVGIS climate data (PVGIS-ERA5, 2005 to 2023).

• Best month: March (706 kWh). Weakest: November (533 kWh), a 1.3x difference.
• March, April, May produce 28.1% of the year; June, October, November produce 21.8%.
• Year-to-year variation: about 303 kWh (4.1%, one standard deviation).
• Sunlight reaching the panels: 1,619 kWh per m² a year.

Rules set by the city or its region, on top of the national scheme. Each one was checked against the official source on the date shown.

• Tokyo Metropolis

  Tokyo residential PV subsidy (FY2026)

  Tokyo's FY2026 household solar subsidy, run by Cool Net Tokyo, pays 150,000 yen per kW (max 450,000 yen) for systems up to 3.75 kW on existing homes, and 120,000 yen per kW above that; new homes get 120,000 yen per kW up to 3.6 kW (max 360,000 yen) and 100,000 yen per kW above. The programme showed as accepting applications on 25 September 2026.

  Source: クール・ネット東京 (Tokyo Metropolitan Center for Climate Change Actions), 令和8年度 家庭における太陽光発電導入促進事業 (checked 2026-09-25)

• Tokyo Metropolis

  New-build solar mandate from April 2025

  Since April 2025 Tokyo requires large house builders (those supplying 20,000 square metres or more of floor area a year in Tokyo) to install solar on new buildings under 2,000 square metres. Existing buildings are not covered.

  Source: 東京都 (Tokyo Metropolitan Government), 太陽光パネルの設置を義務付ける制度が2025年4月から始まります (checked 2026-09-25)

Tokyo ranks 2 of 2 for yield among the cities we model in Japan, and 23 of 41 across every country on Solar Figures. Within one country the prices are the same, so a payback gap between these cities comes from sunshine alone.

Closest yield abroad: Lyon (1,239 kWh per kWp), São Paulo (1,293 kWh per kWp), Milan (1,298 kWh per kWp).

Power you use yourself is worth the retail price (¥31 per kWh); power you export earns ¥14.58. So the share you use at home, by running appliances in daylight or adding a battery, changes the payback. The system cost stays the same in every row (a battery would add to it).

• Net system cost after incentives: ¥1,500,000 for 6 kWp.
• Incentive modelled: No national capital grant -- support is the FIT export tariff (municipal subsidies vary, not modelled).
• 25-year net savings at our default: ¥3,321,674.

At latitude 35.68°N, PVGIS finds the fixed tilt and direction that maximise yearly output. Our figures use a common 35° roof; the table shows what the optimum adds.

In Tokyo a 35° roof is already at the optimum. Most of a roof's value comes from its direction: a roof facing away from the equator loses far more than a few degrees of tilt.