The most basic information that is required for simulation are measured monthly values of:
Global Horizontal Irradiance (GHI)
Total irradiance from the sun on a horizontal surface on Earth.
Monthly average, in W/m².
Air temperature ~2m above the ground.
Monthly average, in °C.
Those monthly values can then be used to calculate other irradiances (e.g. DHI, DNI), if needed with a finer time step.
There are multiple sources for weather data in SimStadt. The source is usually described in the exported CSV files, e.g. from PhotovoltaicPotential or MonthlyEnergyBalance, since the weather data can obviously have a large impact on simulated results.
The currently available methods for data import in WeatherProcessor are:
Monthly global horizontal irradiance and ambient temperature from INSEL offline database. Averages have been calculated from 20-year measurements (1970-1990), in 2000 ground-based weather stations around the world. This data import is the standard one in SimStadt, since it does not require an Internet connection. This dataset is getting old, though, and average temperatures are now approximately 1K higher than in this database.
Monthly global horizontal irradiance and ambient temperature from PVGIS online database. An Internet connection is required in order to use this data import. Downloads are saved in cache, so that the same data is not fetched every time a simulation is run. PVGIS data come from satellite-measurements, which have been calibrated and validated with ground-based weather stations (see PVGIS Data sources and calculation methods). Measurements are more recent than in the INSEL database. Europe data is available from PVGIS-SARAH database, with measurements between 2005 and 2016.
Current API version used in SimStadt is v5.1.
- Hourly global horizontal irradiance and ambient temperature from local TMY3 file, which the user needs to provide manually.
- Monthly global horizontal irradiance and ambient temperature from local TMY3 file, which the user needs to provide manually.
It's possible to use custom data by pasting them inside a TMY3 file.
Those files can be edited in LibreOffice Calc, by opening them as CSV, with comma as delimiter (do not use
merge delimiters, it breaks the header!).
You can then edit:
- Location name (Cell B1)
- Latitude (E1)
- Longitude (F1)
- Elevation (G1)
- GHI, "Global Horizontal Irradiance", in column E
- DNI, "Direct Normal Irradiance", in column H
- DHI, "Diffuse Horizontal Irradiance", in column K
- Dry-bulb, "Dry-bulb ambient temperature", in column AF
Those values should be enough for every SimStadt simulation. The other columns can be left as-is or renamed NaN to indicate that they are not consistent anymore. They should not be deleted though, since that would change the column id of required data.
- Sky temperature
- Global Irradiance in Plane of Array
Hourly irradiance values
- Gordon, J. M., and T. Agami Reddy. "Time series analysis of hourly global horizontal solar radiation" Solar Energy 41.5 (1988): 423-429.
Auto-regressive model used to create synthetic hourly values from monthly values.
Used in INSEL
Diffuse horizontal irradiance
- Orgill, J. F., and K. G. T. Hollands. "Correlation equation for hourly diffuse radiation on a horizontal surface." Solar Energy 19.4 (1977): 357-359.
Model used to estimate Diffuse Horizontal Irradiance from Global Horizontal Irradiance.
Used in INSEL
- Swinbank, W. CQJR. "Long‐wave radiation from clear skies." Quarterly Journal of the Royal Meteorological Society 89.381 (1963): 339-348.
- Fuentes, Martin K. "A simplified thermal model for flat-plate photovoltaic arrays". No. SAND-85-0330. Sandia National Labs., Albuquerque, NM (USA), 1987