PVGIS · SolarMapped
Solar potential in Japan
These figures are the unweighted mean of the city locations listed below, not a national average. Two urban points do not represent an entire country, its roofs or its solar installations.
Explore on the solar map ↗Sampled-city benchmark
PV output is estimated electricity from 1 kWp of installed solar panels. Irradiation is sunlight energy received per square meter on the optimally tilted panel plane; it is not electricity.
For a 5 kWp system, multiply the electricity values by five. This simple scaling does not account for roof-specific shading or equipment constraints.
Range across these cities: 1,284–1,348kWh/kWp/year. Panel tilt and direction are location-specific; see each city.
Monthly solar irradiation and PV output
Highest-output month: March · 127.6kWh/kWp/month. Lowest-output month: June · 96.7kWh/kWp/month.
The chart and table use the mean of the listed cities for each month.
| Month | Estimated PV output (kWh/kWp/month) | Solar irradiation (kWh/m²/month) |
|---|---|---|
| January | 116.8 | 138.6 |
| February | 110.4 | 132.2 |
| March | 127.6 | 157.1 |
| April | 122.6 | 154.9 |
| May | 119.8 | 155.4 |
| June | 96.7 | 128.2 |
| July | 101.1 | 136 |
| August | 114.9 | 154.5 |
| September | 99.6 | 131.5 |
| October | 101.4 | 129.8 |
| November | 98.3 | 121.9 |
| December | 107.5 | 128.9 |
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Data and methodology
PVGIS 5.3 (European Commission Joint Research Centre), crystalline silicon, fixed free-standing installation, 1 kWp, 14% system losses, equator-facing panels with optimized tilt and the terrain horizon. Long-term climate estimates are not a forecast or a roof survey. Nearby buildings, trees, roof constraints, snow and local conditions can change actual output.
- Tokyo — Reference coordinates: 35.68, 139.69; Climate dataset / years: PVGIS-ERA5 / 2005–2023; Data retrieved: .
- Osaka — Reference coordinates: 34.69, 135.5; Climate dataset / years: PVGIS-ERA5 / 2005–2023; Data retrieved: .
PVGIS methodology · Sources and assumptions (English) · Download the underlying data (JSON)