Weather Data
Because meteorological data are often important input parameters in the simulation of energy systems, weather data can be processed in TOP-Energy. Weather data play an important role in calculating heating and cooling demands and energy generated by solar and wind. For example, a heat demand is determined as a function of ambient temperature, and the output of a wind turbine is calculated based on wind speed.
Weather data are stored in a separate form in the Project Master Data and are transferred by default to the Simulation form Reference condition and the forms of the weather-dependent components, such as Solar Radiation and Wind. If required, this master data link can also be removed.
Adding and Removing a Weather Data Set
In the project master data, you can add several weather data sets. To do this, use the 
Add weather data set icon (see following figure). In this way, for example, you can include for Germany not only a DWD Test Reference Year for an average year, but also the Test Reference Years with extreme winter and extreme summer.
Rename the added part in the following dialog.
Using the pop-up menu called by the 
button you can remove any additionally inserted data set (see following figure).
One weather data set must be kept at least. When trying to delete the last set, a message appears with the option to overwrite the set with the default data.
Simple Import Into TOP-Energy
Via an integrated interface in the form Weather data of the project node, you can easily import weather data into TOP-Energy: for Germany from DWD and for other countries from PVGIS. To do this, select the desired source from the drop-down list and then Perform (see following figure).
Before that, you determine the Location for which the weather data will be loaded, also in the project master data (see the following figure).
During import, the reference year is shifted to the Start year specified in the Project ribbon and the time zone also specified there (see the following figure).
When executing the import of the weather data, the existing data of the data set are overwritten. Existing master data links are retained, which means that the respective data are also overwritten in the linked components.
German Weather Data From DWD
Prerequisite for the import of the weather data from DWD is your registration with DWD and the input of your personal login data for the DWD. You store these in the Extras ribbon in the settings group with the 
DWD settings button. To register with the DWD for the first time, you can follow the link from the input window.
The Deutsche Wetterdienst (DWD, Germany’s National Meteorological Service) provides a separate Test Reference Yeardata set for each square kilometer in Germany. A Test Reference Year (TRY) represents an average but characteristic weather pattern for the year. The location-accurate Test Reference Years of Germany are available for average, extreme, and future weather conditions. Test Reference Years with the reference periods 1995-2012 and 2031-2060 are available. Detailed information on the TRY data sets is available from DWD.
To load the data, first select whether to import an average year, a year with an extreme summer, or a year with an extreme winter (see the following figure).
The data sets for an Average year include averaged weather conditions typical for a year.
The data sets for years with Extreme summer/winter include a real annual period from the period under consideration with a very warm summer half-year or with a very cold winter half-year.
In the next step, select the Reference period (see the following figure).
The basis of the data sets for the Reference period 1995-2012 are measurement and observation time series of the period 1995 to 2012.
Climate models with relevance for a time horizon from 2031 to 2060 form the basis for the data sets of the Reference period 2031-2060. Using these data, the expected future climate conditions can be considered in the simulation.
Click the Perform button to import the data sets from the DWD (see the following figure).
If you have not yet stored any login data for the DWD, the following window will open and give you the opportunity to do so.
Otherwise, the weather data import is started immediately (see the following figure).
After successful import you can close the window (see the following figure).
The imported weather data are now stored in the master data of the project (see the following figure) and can be used throughout the project.
If the weather data do not load, please connect to the Internet, use your correct username, and follow the instructions for the error message.
International Weather Data From PVGIS
If your project has a Location outside Germany, you can import the weather data of PVGIS for it (see following figure).
The Photovoltaic Geographical Information System (PVGIS) provides a typical meteorological year for sites worldwide for the period 2005 to 2020 (PVGIS 5.2). A typical meteorological year (TMY) is a set of meteorological data with data values for every hour in a year for a given geographical location. The data are selected from hourly data for the full time period available. PVGIS generates a TMY following the ISO 15927-4 procedure. The methodology is further described in the open access publication:
Huld, Thomas; Paietta, Elena; Zangheri, Paolo; Pinedo Pascua, Irene: Assembling Typical Meteorological Year Data Sets for Building Energy Performance Using Reanalysis and Satellite-Based Data, Atmosphere 2018, 9, 53; doi:10.3390/atmos9020053.
The solar radiation database (DB) used is the default DB for the given location, either PVGIS-SARAH, PVGIS-NSRDB, or PVGIS-ERA5. The other meteorological variables are obtained from ERA-Land reanalysis data for PVGIS 5.2.
Some parameters provided by DWD for Germany are not available from PVGIS: Irradiance of atmospheric heat radiation, Cloud amount, and Water vapor content. For these parameters, „Not available in PVGIS“ null … is displayed (see the following figure).
Direct solar irradiance (on the horizontal surface) is also not included in the raw PVGIS data, but is automatically calculated by TOP-Energy as the difference between global irradiance and Diffuse solar irradiance.
When moving the time series imported from PVGIS to the Start year selected in the Project ribbon, a conversion between the time zones may be necessary. To facilitate the conversion, one day (24 h) is automatically added to the front and back of the time series. The resulting excess data points are ignored in a subsequent simulation. This is indicated by the Simulator message 8277 (see following figure):
The time steps of the input time series do not coincide. Altogether . . . data points were ignored. The following time series are partially outside the simulated time period: …
As an alternative to the automatic import, you can also download the PVGIS data individually from the PVGIS website: https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html and then import it into the ETA.
Weather Data in the ETA
With the supplied software tool for time series ETA, you can process weather data and use supplied standard weather data.
Germany Weather Standard Time Series in ETA
The ETA has also default time series with meteorological data from Germany. These include test reference years based on 2010 observational data (measurements 1988-2007: Testreferenzjahre_Beobachtungsdaten_2010) and a 2035 climate simulation (2021-2050: Testreferenzjahre_Klimasimulationen_2035) for 15 climate regions.
Importing More Weather Data Into the ETA
You can import weather data into the ETA like other time series.
The DWD offers further weather data for the years from 1951 onwards, broken down by cities and the elements of soil, wind, precipitation, sunshine duration, temperature, and humidity. You can download these data from the DWD website and import them into the ETA with the following import settings.
When importing data from sources with other date formats, you can open the help with a click on the blue question mark behind the input field (see figure above).
