Solar Potential Calculator
Annual energy yield, optimal tilt, and monthly breakdown for any location.
About
The calculator returns the annual energy a PV array of given peak power would produce at your coordinates, plus the optimal tilt and the monthly breakdown. Backed by satellite-derived irradiance data, not regression models — accurate to within ±5% in most regions.
How it works
- Pick or enter latitude and longitude. Use a preset for a major city if you just want to explore.
- Set system size (kWp). 1 kWp ≈ 2.5 modern solar panels.
- The calculator queries PVGIS or NREL PVWatts and returns annual kWh, optimal tilt and a monthly chart.
Frequently asked questions
How accurate is this PV potential calculator?+
PVGIS and NREL PVWatts are the same data sources commercial installers use. Long-run accuracy is ±5% for typical residential installs. Year-to-year variation can be ±10–15% depending on weather.
What's a typical annual yield in kWh per kWp?+
Northern Europe (UK, Germany, Netherlands): 850–1,100 kWh/kWp. Southern Europe (Spain, Italy, Greece): 1,300–1,700. US Sun Belt (Arizona, California, Texas): 1,500–1,900. Australia: 1,300–1,800. Coastal northwest US: 950–1,200.
Why does the optimal tilt differ from my latitude?+
The classical 'tilt = latitude' rule maximises annual yield assuming flat horizon. PVGIS optimises against your actual horizon and seasonal demand profile, so optimal tilt is usually 5–15° flatter than latitude in cloudy/diffuse climates.
Does it account for shading?+
No. PVGIS uses far horizon shading from terrain only. Tree, chimney and neighbour shading need a manual derate (typically 5–25%) or a dedicated tool like Solmetric / SunEye / Aurora.
Can I use this for a balcony solar kit?+
Yes — set system size to your kit's panel total in kW (0.6–1.6 kWp typical). The result is upper-bound; real balcony output is 70–90% of this due to vertical mounting and partial shading from the building.