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NASA POWER irradiation data
Calculation3 min readUpdated: 2025-06
SolarDim Pro automatically retrieves real solar irradiation for the site via the NASA POWER API. Data is averaged over 9 years of satellite measurements (2015–2023) at the exact GPS coordinates of the project.
| Parameter | Value | Source |
|---|---|---|
| Granularity | Monthly (12 values/year) | NASA POWER API |
| Time horizon | 2015–2023 (9 years) | Satellite measurements |
| Variable retrieved | ALLSKY_SFC_SW_DWN (GHI) | Global Horizontal Irradiance |
| Geographic precision | Exact GPS point | lat/lon of project |
If auto-detection fails (no coverage zone), SolarDim Pro uses a local database of 60+ African and European cities with reference irradiation values. You can always adjust manually with the slider.
Common mistakes
- Using a rough guess for irradiation instead of NASA POWER data for the exact site
- Using the annual average instead of the worst month to size the PV array
- Not manually adjusting when NASA coverage fails for a remote area