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Solargis s.r.o. http://Solargis.info/index.html provides climate data for the study of Solar Energy systems in the form of full historical time-series and TMY.
 

It provides namely solar radiation required for the simulation within PVsyst, from 01/1994/1999/2007 (depending on region) up to present, with a spatial resolution of approx 3km.:

•Global horizontal irradiance (GHI or GlobHor)

•Diffuse horizontal irradiance (DIFF or DiffHor)

•Air temperature (T): time coverage: 01/1991 up to present

•Direct normal irradiance (DNI or BeamHor)  are also available for concentrating systems.

•Aerosol Optical Depth (AOD) - to be used in the future by PVSYST

•Precipitable water (pw)  - to be used in the future by PVSYST

 

Refer to https://solargis.com/products/evaluate/tech-specs for more details on coverage.

 

In the Solargis irradiance dataset, please note that :

•with hourly files ordered from climData: the effect of far shadings from mountains at sunrise and sunset is not included, unless explicitly requested, which means there in mountainous regions an horizon mask must be applied in the project area of PVSyst.

•with Monthly files available from Prospect: the effect of far shadings from mountains at sunrise and sunset is included.

•the diffuse circumsolar radiation is included in the DHI component (diffuse horizontal), which means that the data is compatible with the use of the Perez-transposition model.
 

The Solargis data are available for a fee.

 

 

 

Details of the Method   (from https://solargis.com/docs/methodology/solar-radiation-modeling)
 

The solar radiation retrieval in Solargis is basically split into 5 steps :

1.First, the clear-sky irradiance is calculated using the clear-sky model SOLIS, which needs Aerosols, water vapour and Ozone inputs

a.Aerosols are represented by Atmospheric Optical Depth (AOD), which is derived from the global MACCII database. The model uses daily variability of aerosols to simulate more precisely the instantaneous estimates of DNI and GHI. Use of daily values reduces uncertainty, especially in regions with variable and high atmospheric load of aerosols.  

b.Water vapour is also highly variable, but compared to aerosols, it has lower impact on magnitude of DNI and GHI change. The daily data are derived from CFSR and GFS databases for the whole historical period up to the present time.

c.Ozone has negligible influence on broadband solar radiation and in the model it is considered as a constant value.
 

2.Second, the satellite data are used to quantify the attenuation effect of clouds by means of cloud index calculation. The data elaboration uses the best available data sources (METEOSAT © EUMETSAT, ERA Interim © ECMWF), NCEP GFC and CFS (Information about GOES satellites, information about MTSAT satellites. Read also PVSyst main page on satellites.)
The Cloud model estimates cloud attenuation on global irradiance. Data from meteorological geostationary satellites are used to calculate a cloud index that relates radiance of the Earth’s surface, recorded by the satellite in several spectral channels with the cloud optical transmittance. A number of improvements are introduced to better cope with complex identification of albedo in tropical variable cloudiness, complex terrain, at presence of snow and ice, etc. Other support data are also used in the model, e.g. altitude and air temperature.
 

3.Third, the clear-sky irradiance is coupled with cloud index to retrieve Global Horizontal Irradiance (GHI) (all-sky irradiance).
 

4.Fourth, the other solar irradiance components - direct, diffuse - are calculated From GHI:

a.Direct Normal Irradiance (DNI) is calculated by modified Dirindex model.

b.Diffuse horizontal irradiance is derived from GHI and DNI.
 

5.Last, irradiance may be further corrected for shading effects from terrain. The model for simulation of terrain effects (elevation and shading) is based on the SRTM3 elevation data. Model by Ruiz Arias is used to achieve enhanced spatial representation – from the resolution of satellite (3 to 4 km) to the resolution of digital terrain model. Considering the shading from terrain, the spatial resolution of data products is enhanced up to 3 arc-seconds (which is about 90 metres at the equator, less towards the poles). Direct, circumsolar and isotropic diffuse components are corrected for terrain shadowing.
For full historical time series or TMY hourly files ordered via Solargis climData, the shading is by default not applied. It can be applied if explicitely requested by users.
For longterm monthly averages aggregated data ordered via Solargis iMaps, the shading is applied.
The horizon in Solargis can be edited and copied into a text file from the tool Prospect.

 

All Inputs to Solargis Model are summarised here.