Data Sources
SolarScope's analysis engine integrates three authoritative data sources to provide comprehensive, high-quality solar resource data. This page explains each source, its coverage, methodology, and how it contributes to your analysis.
NASA POWER
The Prediction of Worldwide Energy Resources (POWER) project from NASA's Langley Research Center provides satellite-derived surface meteorological and solar energy parameters.
Coverage: Global, including all land areas and most ocean regions
Spatial resolution: 0.5° × 0.5° (approximately 55 km at mid-latitudes)
Temporal resolution: Monthly and annual averages, with daily data available
Historical period: 1981 to present (20+ years of data)
Data type: Climatological averages derived from satellite observations and GEOS atmospheric modeling
Parameters used:
- ALLSKY_SFC_SW_DWN (GHI — All-sky surface shortwave downward irradiance)
- ALLSKY_SFC_SW_DNI (DNI — Direct normal irradiance)
- ALLSKY_SFC_SW_DIFF (DHI — Diffuse horizontal irradiance)
- T2M (Surface air temperature at 2m height)
- WS10M (Wind speed at 10m)
NASA POWER data is the primary data source for all SolarScope analyses worldwide. It's freely available and widely validated against ground measurements globally.
NREL NSRDB
The National Renewable Energy Laboratory's National Solar Radiation Database (NSRDB) provides high-resolution hourly solar resource data for the Americas, India, and parts of Europe and Asia.
Coverage: Continental US, Alaska, Hawaii, Canada, Mexico, Central America, South America, India, and select other regions
Spatial resolution: 4 km × 4 km (significantly higher than NASA POWER)
Temporal resolution: Hourly time series data
Historical period: 1998 to present (Physical Solar Model, PSM)
Data type: Satellite-derived irradiance using GOES-16/17 satellite data
For locations within NSRDB coverage, SolarScope supplements NASA POWER data with NSRDB values for higher spatial accuracy. NSRDB data is particularly valuable for complex terrain sites where the 0.5° NASA POWER grid may not capture local topographic effects.
ArcGIS
Esri's ArcGIS platform provides two services used by SolarScope:
Geocoding: ArcGIS World Geocoder converts street addresses to precise GPS coordinates for project location entry.
Basemap: ArcGIS provides the satellite imagery basemap used in Site Studio for site mapping and array layout.
Data Quality and Validation
All three data sources are extensively validated against ground measurement networks. NASA POWER validation studies report mean bias errors of ±5% for monthly GHI averages. NREL NSRDB achieves ±3–4% mean bias error for monthly GHI in well-covered areas.
SolarScope does not apply site-specific corrections for local shading, soiling, or aerosol loading. For bankable energy assessments, consider supplementing SolarScope analysis with site measurements and PVsyst or equivalent detailed modeling.