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 TMY | Extended TMY | Available on request |
| P50 | P50, P75, P90 | Pxx | |
| Coverage | Global, except for ocean and polar regions | ||
| Spatial resolution of satellite data | 1-2 km | ||
| Time granularity | 60 minute | ||
| Timespan of database used to generate TMY | January 2007 to 7 days ago | ||
| Parameters |
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| Files provided |
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| Time zone |
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| Database update frequency | Daily (recent months are considered in TMY senario) | ||
| Acccess method | Data can be ordered and downloaded via the Solcast API Toolkit | ||
| Download wait time | Typically 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 granularity | Basic time series | Extended time series | Available on request |
| 60 minute | 5, 10, 15, 20,30 or 60 minute, native satellite | 1 minute | |
| Coverage | Global, except for ocean and polar regions | ||
| Spatial resolution of satellite data | 1-2 km | ||
| Timespan of database | January 2007 to 7 days ago (for past 7 days to present time, or forecasts, use our Live and Forecast data) | ||
| Parameters |
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| Files provided |
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| Time zone |
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| Database update frequency | Daily (Live and Forecast data is also available) | ||
| Acccess method | Data can be ordered and downloaded via the Solcast API Toolkit | ||
| Download wait time | Typically 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
| Coverage | Global, except for ocean and polar regions |
| Spatial resolution of satellite data used | 1-2 km |
| Time granularity | Monthly |
| Timespan of database used to generate monthly averages | January 2007 to 7 days ago |
| Parameters |
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| Database update frequency | Daily (recent months are considered in monthly averages) |
| Acccess method | Data can be ordered and downloaded via the Solcast API Toolkit |
| Download wait time | Typically 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.
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