Koumi Kogen is a 10 MW solar power plant in Nagano, Japan. Based on its capacity (estimated), it can supply roughly 4,339 homes (estimated). It ranks #504 of 659 Japan power plants by installed capacity. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, solar supplies about 9.8% of Japan's electricity; the national grid averages 477 gCO₂/kWh (32.7% low-carbon) (2025).
Plant data: WRI Global Power Plant Database (CC BY 4.0), id WKS0073956.
Installed capacity (MW), WRI Global Power Plant Database (CC BY 4.0).
This solar plant converts sunlight directly into electricity with photovoltaic panels. It sits in a warm-summer humid continental climate (Köppen Dfb) — Northern Hemisphere, latitude 36.1°N — which shapes how much energy it can produce and how its output varies through the year.
Monthly mean temperature
Heating degree-days here run 67% above the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.
Climate heat-demand index: 85/100 — this site sits in the top third of the power plants we cover by heating degree-days.
In colder climates, uninsulated hot equipment (boilers, turbines, valves, steam lines) loses proportionally more heat to ambient air — exactly the loss Inzonex modular insulation is designed to cut.
Solar PV loses ~0.35%/°C above 25°C cell temperature — roughly 0.0% at warm-season highs here (estimate).
Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.
The #182 largest solar power plant of 324 in Japan by capacity.
Japan has 324 solar power plants in this dataset, together about 5,687 MW of capacity.
Coordinates 36.077, 138.423 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.
