Documentation

Documentation Accuracy and comparisons

Independent comparisons

Several independent comparisons of solar radiation databases have been performed in recent years. In all these comparisons, Solargis has been identified as the best performing database. Results of two of these comparison studies are available publicly and are summarised below.

IEA satellite data validation study 2014 - by Pierre Ineichen, University of Geneva

This study presents results of a validation in the European and Mediterranean region of satellite-derived irradiation databases in hourly, daily and monthly values. GHI and DNI data from 6 satellite-irradiance-models were compared with high quality measurements from 18 locations. Up to 16 years of continuous measurements have been used for the validation. The locations chosen for validation cover different climate conditions - from desert to oceanic, the latitude varies from 20°N to 60°N, and the altitudes from sea level to 1580 metres.

Solargis has been identified as the data source with the lowest overall bias, lowest mean bias deviation, and lowest RMSD. A summary of the validation results in presented in the table below.

 

 

Solargis Helioclim 3 Solemi Heliomont CM-SAF IrSOLaV
GHI Mean bias 0% 1% 2% 1% 0% 1%
Standard deviation of biases 2.1% 5.1% 4.8% 3.6% 3.7% 4.2%
DNI Mean bias -2% 6% -11% 0% 2% 0%
Standard deviation of biases 5.9% 13.9% 14.5% 9.3% 9.1% 12%

The IEA SHC Task 36 data inter-comparison study 2011 - by Pierre Ineichen, University of Geneva

In this study, GHI and DNI data from five satellite derived irradiation database are compared with high quality measurements from 23 locations across Europe, Middle East and Africa for the year 2006 (365 days). The models validated in this study include:

  • Solargis
  • SoDa Helioclim
  • 3Tier (Vaisala)
  • IrSOLaV
  • University of Oldenburg (EnMetSol-Solis and EnMetSol-Dumortier)

The Solargis database demonstrated the lowest bias and RMSD values amongst all data sources.


Comparison of Annual Global Horizontal Irradiation Maps for Australia - by Jessie K Copper and Anna Bruce, University of New South Wales

This study undertook a cross comparison of the annual global horizontal irradiation data sources available for Australia. The models validated in this study include: Solargis, Meteonorm 7.2, NASA POWER, Vaisala, MERRA-2, Australian Bureau of Meteorology (BoM) gridded solar data.

Besides other conclusions also this study found that Solargis database demonstrated the lowest bias and RMSD values amongst compared data sources.

Solargis NASA POWER MERRA-2 Australian Bureau of Meteorology
GHI Mean bias 0.0% -0.9% 5.9% -0.4%
Standard deviation of biases 1.50% 3.72% 4.46% 2.23%

Other studies

Solar Resource Assessment over Kuwait: Validation of Satellite-derived Data and Reanalysis Modeling by Majed AL-Rasheedi, Christian A. Gueymard, Alaa Ismail and Salem AL-Hajraf, EuroSun 2014 Conference Proceedings, 16-19 September 2014