Typical Meteorological Year

Historical and TMY

Typical Meteorological Year (TMY) data for solar energy simulations and yield analysis

A collation of historical weather data derived from a multi-year time series selected to present the unique weather phenomena with annual averages that are consistent with long term averages.

Typical Meteorological Year
CLOUD AND IRRADIANCE TRACKING

Tracking the world's clouds in the finest detail

Designed for Solar, from the ground up. Never rely on generic weather model data again. Solcast's real time and forecast data tracks and forecasts real clouds at a resolution of 1-2km and 5 minutes. Our irradiance data and PV power data is updated every 5 to 15 minutes, downscaled to 90 metre resolution. Aerosol and albedo effects are explicitly treated.

Integrate

Integrate directly with your PV software, or upload with multiple file format options

Solcast data is available directly in PVSyst, SAM, PlantPredict and PV*Sol. Support for other softwares via industry standard data formats.

Data Access

Multiple probabilistic scenarios available for due diligence and solar resource assessment

Direct API download for TMY P50 data. TMY PXX scenarios (P75, P90, P95) downloads through the Solcast API Toolkit. Multiple file types supported (CSV, PVsyst, TMY3, SAM).

Data Accuracy
Low Uncertainty

Validation

Dataset supported by independent global validation

The data has low uncertainty and a quantified error range, making the data suitable for resource assessment, yield analysis, financial modelling, and any application requiring precision irradiance data.

TMY Data Specifications

Geographic coverage

Global (note: far ocean and polar regions are coarser resolution)

Temporal coverage

15, 20,30 or 60 minutes (period-mean values)

Spatial resolution

90 meters (irradiance, PV power, snow soiling, cloud parameters, and other parameters across all regions)

Pxx (Probability of exceedance)

P50, P75, P90, P95

Data parameters

The following data parameters are available.

  • Global Horizontal Irradiance (GHI) (W/m2)^
  • Direct Normal Irradiance (DNI) (W/m2)^
  • Diffuse Horizontal Irradiance (DHI) (W/m2)^
  • Global Tilted Irradiance (GTI) (W/m2)^
  • Advanced PV Power Output (MW)^
  • Rooftop PV Power Output (kW)^
  • Cloud Opacity (%)
  • Air Temperature (°C)
  • Solar Zenith Angle (°)
  • Solar Azimuth Angle (°)
  • Albedo (%)
  • Wind Gust (m/s)
  • Wind Speed (10m) (m/s)
  • Wind Speed (100m) (m/s)
  • Wind Direction (10m) (°)
  • Wind Direction (100m) (°)
  • Relative Humidity (%)
  • Precipitation Rate (mm/h)
  • Surface Pressure (hPa)
  • Precipitable Water (kg/m2)
  • Dewpoint Temperature (°C)
  • Snow Depth Water Equivalent (cm)
  • Snow Depth (cm)
  • Snowfall Rate (cm/h)
  • Snow Soiling Loss - Rooftop (%)
  • Snow Soiling Loss - Ground Mounted (%)
  • Thunderstorm Potential - CAPE (j/kg)

^ Clear-sky scenarios also available for these parameters

Data access

API or Web download

Download wait time

No wait time

Data formats

CSV, JSON, PVsyst, SAM, TMY3

Time zone

UTC (default for Solcast), longitudinal (default for SAM, PVsyst, TMY), or user-set

Commonly Asked Questions about TMY Data

TMY, or Typical Meteorogical Year, data is a synthetic dataset that represents average weather conditions in a specific location. In solar applications, accurate, bankable TMY data representing typical irradiance years are used for modeling and simulating the performance of assets under average weather conditions.

TMY data is calculated by analysing and combining real periods from a multi-year dataset based on statistical criteria to create a synthetic year that reflects typical weather conditions. Solcast’s TMY API selects representative periods to match the average historical irradiance, and includes key weather parameters including multiple solar irradiance measures, temperature, overall climate conditions, and even albedo and aerosol. Check our irradiance methodology.

TMY data is preferred for project financing, and is useful for representing weather conditions that vary every single day. Historical time series data is best when analysing long term weather trends (like snow soiling), correlation of weather with other circumstances (like energy prices) or variation and risk over time. TMY data is ideal for designing and optimising assets, bankable energy assessments for project financing, and performing long-term energy yield projections.

While a viable solar project may be feasible and potentially profitable, a bankable solar project meets stricter criteria required by financiers, including extensive risk assessments and credible performance data. Being bankable means that a project is considered reliable and financially sound to secure funding from investors or lenders. So, it’s important to choose globally validated, bankable TMY and historical data when doing solar resource assessment. Check the recent DNV bankability study of Solcast data, and see how it compares with other historical irradiance data providers.

P50 and P90 are probabilistic scenarios, used for managing and understanding the risk of variable weather conditions, where the number denotes the percentage of years that will exceed that value. For due diligence and solar resource assessment, having multiple probabilistic scenarios is beneficial for better decision making and risk management. TMY P50 represents the median or average conditions, reflecting typical long-term weather patterns while TMY P90 represents a more conservative “low end” scenario, indicating conditions that are exceeded 90% of the time, used to understand the downside risk of a “bad year”. Solcast offers probabilistic scenarios for TMY at any “Pxx” level.