Data and specifications

Solar resource and weather data in time series, typical meteorological year (TMY) and monthly averages

Evaluating the solar resource is crucial for any solar energy investment decision. Project developers, technical consultants, and asset managers require reliable data to make informed, high-value, low-risk decisions.

Not all satellite-derived solar irradiance data is created equal. Solcast data has very low uncertainty, is delivered rapidly (in minutes), is available in multiple formats, and includes free credit to get you started.

Solcast produces three types of solar resource and weather data: Time Series, Typical Meteorological Year (TMY), and Monthly averages. Sign up using the Solcast toolkit and get free credits so you can download some sample data, that’s relevant for you, for free, right now.

TMY

A TMY, or Typical Meteorological Year, is a collation of historical weather data for a specified location for a one year period. The dataset is derived from a multi-year time-series specifically selected so that it presents the unique weather phenomena for the location, and provides annual averages that are consistent with long term averages. All TMY files contain exactly 8760 rows of data, each corresponding to an hourly period in an ‘average’, or ‘typical’ year. TMY data is frequently used by solar engineers, as a data input to energy system simulations.

Solcast offers two variants of TMY: Basic (P50 only) and Extended (P50, P75 & P90). See details on the Solcast pricing page

tmy data specifications

Pxx (Probability of exceedance)Basic TMYExtended TMYAvailable on request
P50P50, P75, P90Pxx
CoverageGlobal, except for ocean and polar regions
Spatial resolution of satellite data1-2 km
Time granularity60 minute
Timespan of database used to generate TMYJanuary 2007 to 7 days ago
Parameters
  • Global Horizontal Irradiance (GHI, W/m2)
  • Direct Normal Irradiance (DNI, W/m2)
  • Diffuse Horizontal Irradiance (DIF, DHI, W/m2)
  • Temperature (TEMP, °C)
  • Wind Speed (WS, m/s)
  • Wind Direction (WD, °)
  • Relative Humidity (RH, %)
  • Surface Pressure (AP, hPa)
  • Precipitable Water (PWAT, kg/m2)
  • Snow Depth (SWDE, cm)
  • Dew Point (DWPT, °C)
Files provided
  • Solcast standard CSV
  • PVsyst
  • SAM
  • TMY3
Time zone
  • UTC (default for Solcast)
  • Longitudinal (default for SAM, PVsyst, TMY)
Database update frequencyDaily (recent months are considered in TMY senario)
Acccess methodData can be ordered and downloaded via the Solcast API Toolkit
Download wait timeTypically 1 to 9 minutes

Time Series

Time series data is a historical record of weather data for a specified location. Time series of solar radiation and meteorological variables are used during the simulation of energy production of solar power plants to understand expected year-to-year variability, seasonal or intra-day energy generation profile, and for calculation of energy estimates for P90 or other probabilistic scenarios. Recent time series data can be used to understanding how much solar radiation was reaching a site over previous months, to determine how much energy your solar panels should have generated, or to calibrate equipment, or to update energy models.

Solcast offers two variants of Time Series: Basic (hourly granularity only) and Extended (all time granularities from hourly down to 5 minute). See details on the Solcast pricing page

TIME SERIES DATA SPECIFICATIONS

Time granularityBasic time seriesExtended time seriesAvailable on request
60 minute5, 10, 15, 20,30 or 60 minute, native satellite1 minute
CoverageGlobal, except for ocean and polar regions
Spatial resolution of satellite data1-2 km
Timespan of databaseJanuary 2007 to 7 days ago (for past 7 days to present time, or forecasts, use our Live and Forecast data)
Parameters
  • Global Horizontal Irradiance (GHI, W/m2)
  • Direct Normal Irradiance (DNI, W/m2)
  • Direct (Beam) Horizontal Irradiance (EBH, W/m2)
  • Diffuse Horizontal Irradiance (DIF, DHI, W/m2)
  • Cloud Opacity (%)
  • Solar Zenith angle (°)
  • Solar Azimuth angle (°)
  • Temperature (TEMP, °C)
  • Wind Speed (WS, m/s)
  • Wind Direction (WD, °)
  • Relative Humidity (RH, %)
  • Surface Pressure (AP, hPa)
  • Precipitable Water (PWAT, kg/m2)
  • Snow Depth (SWDE, cm)
  • Dew Point (DWPT, °C)
Files provided
  • Solcast standard CSV
  • PVsyst
Time zone
  • UTC (default for Solcast)
  • Longitudinal (default for PVsyst)
Database update frequencyDaily (Live and Forecast data is also available)
Acccess methodData can be ordered and downloaded via the Solcast API Toolkit
Download wait timeTypically 1 to 9 minutes

Regarding time granularity, Native satellite times are 6-minute average estimates centered on the time of the satellite scan over the actual location.

Regular period averages (at 5, 10, 15, 30 or 60 minutes) are interpolations and averages derived from the native data. The shorter periods, particularly 5 minutes, may tend to result in estimates that are minimise error, but are smoother compared to corresponding measurements, due to interpolation from the less granular satellite scans. Contact us if you need synthetically generated 1 or 5 minute irradiance data with realistic cloud variability.

Monthly Averages

Solcast provides averaged monthly values of solar radiation data and other weather parameters. Monthly averages provide a high-level overview of the solar resource available at a particular site. They are useful during the early stages of solar site prospecting when a coarse energy estimate is acceptable.

See details on the Solcast pricing page

monthly averages data specifications

CoverageGlobal, except for ocean and polar regions
Spatial resolution of satellite data used1-2 km
Time granularityMonthly
Timespan of database used to generate monthly averagesJanuary 2007 to 7 days ago
Parameters
  • Global Horizontal Irradiance (GHI, W/m2)
  • Direct Normal Irradiance (DNI, W/m2)
  • Diffuse Horizontal Irradiance (DIF, DHI, W/m2)
  • Temperature (TEMP, °C)
  • Wind Speed (WS, m/s)
Database update frequencyDaily (recent months are considered in monthly averages)
Acccess methodData can be ordered and downloaded via the Solcast API Toolkit
Download wait timeTypically 1 to 9 minutes

Test now, free

Get free historical data credits when you sign up, so you can try our data for yourself. You can download data automatically within around 1 to 9 minutes of submitting your request.