Solargis Comparison

Solcast is independently validated as the lowest uncertainty solar resource dataset
Historical and Tmy

Compared with Solargis, Solcast has similar or lower uncertainty, is faster to access, and is generally cheaper and easier to use.

Model inputs

The Solargis and Solcast methodology is relatively similar. Both are semi-empirical and are satellite-derived. Both rely on validated, published models to build a clear sky model, and use proprietary cloud detection models.

The input satellite imagery is similar, with Solargis using approx. 3-4km grids and Solcast using approx. 2km grids. Both datasets downscale solar irradiance parameters, Solcast to 150m and Solargis 250m.

Accuracy and validation

Both Solcast & Solargis models have been independently validated using multiple locations globally. Solcast’s model has been validated at over 70 measurement sites, available in the public domain. You can request a copy of Solcast's validation report, and for further reading see error statistics for live and forecast data, and also for historical data and statistics.


Satellite coverage

Solargis and Solcast both offer near-global data coverage (polar and remote ocean regions are excluded or have lower data quality).

Data access + availability

Solargis products are available via web apps, with some API access available. Solcast products are available via the easy to use with API access for all products. Both offer historic and forecast data, including Timeseries & TMY data.

Solargis and Solcast make data available to download in formats ready to upload to common PV modelling software, including PVsyst, Helioscope, SAM, Homer, Plant Predict and more. Solcast has direct integrations with PVsyst and SAM, where Solcast data can be accessed directly from within those PV modelling software packages.

Historical record

The Solargis database is compiled using high-resolution new satellites, and lower-resolution, pre-21st century satellites. Data coverage begins at 1994/1999/2006 depending on location.

Solcast only uses data from recent generation geostationary meteorological satellites (GMS). For this reason, we do not use data prior to 2007 due to climate change and satellite data quality issues. This maximises data quality and validity, while still providing 15+ years of data history from which to sample for interannual variability. Users can be sure our accuracy and validation statistics apply to all our data, not just the most recent half of it!

Data types + granularity

Solargis and Solcast both offer hourly TMY data and Timeseries data at various time granularities.

Solcast Solargis
Timeseries 1, 5, 10, 15, 30 & 60min 1, 5, 10, 15, 30 & 60min
TMY P50, P75, P90, P95, Pxx P50, P90, Pxx

Parameters available

Solcast Solargis - Basic Solargis - Pro
Global horizontal irradiance (GHI)
Direct normal irradiance (DNI)
Diffuse horizontal irradiance (DHI)
Global tilted irradiance (GTI/POA)
Direct (Beam) horizontal irradiance
Cloud Opacity
Albedo Add-on
Wind direction
Wind speed
Precipitable water
Relative humidity
Surface pressure
Dew point
Snow depth
Clear-sky irradiances

Elevation and altitude

Solcast maps altitude and elevation with a grid size of 150m2, compared with a 250m2 grid used by Solargis. In regions of extreme local topography, Solcast maps small elevation changes at a finer level than Solargis.

Additional Services/Tools available

Solargis has supporting simulation software (pvPlanner, PVspot and iMaps) that assists users in prospecting and pre-feasibility PV modelling. If you need PV simulation tools and features, you may be better with Solargis - Solcast is a data provider rather than a tools provider.

Price and access

Solcast Solargis
Price $$ $$$$
Free data for evaluation Prospect app only
Free data for academics and students

Historic Data Products

Time Series
The complete suite of irradiance and weather data required for effective monitoring, operation, and forecasting at your large-scale solar farm.
Typical Meteorological Year (TMY)
The complete suite of irradiance and weather data required for effective monitoring, operation, and forecasting at your large-scale solar farm.