The design and simulation software for solar thermal systems

T*SOL is a dynamic simulation program for the design, optimization and calculation of solar thermal systems.
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T*SOL is the simulation program with which you can calculate the yield of a thermal solar system. No matter whether for domestic water heating, heating support, swimming pools or process heat, with T*SOL you can optimally design your planned solar thermal system, dimension storage and collector arrays (also east / west roofs) and determine the economic efficiency.

At the start of the design process, you have a large selection of all relevant systems for domestic hot water heating and heating support, as well as for swimming pools and process heat. During the design, you will be supported with dimensioning suggestions and can use a parameter variation to find the optimal combination, e.g. of storage size and collector area.

After the simulation you will receive a comprehensive and appealing project report with all system data as well as detailed simulation and profitability results. This report also contains all the data necessary to be recognized as evidence by BAFA.


Product highlights

More program details

Parameter variation

You can vary up to two parameters at the same time (e.g. collector area and storage volume) to find out the optimal values for the combination of target variables including "efficiency", "solar fraction", "additional energy" and "solar yield". </ p >

Energy label

Since September 26, 2015, it has been mandatory for all manufacturers, dealers and craftsmen in the EU to label heating devices for space heating and hot water systems in respect of their energy use. T*SOL simulates the energy efficiency of solar thermal supported heating systems and generates the composite system label for you.

Over 200 pre-configured solar thermal systems

All components can be parameterized in detail or selected from the database.

  • Domestic hot water
  • Heating
  • Swimming pool
  • Process heat
  • Large systems

Global climate data available

T*SOL provides you with the latest TMY data of the DWD (current state 2017, averaging period 1995-2012) for Germany and more than 8,000 further climate locations for the whole world based on Meteonorm 8.1. You can use the interactive map to conveniently select the climate data. Locations not included are interpolated using satellite data and neighboring ground measuring stations. The import of your own measurement data takes place via files in DWD, Meteonorm or WBV format.

Design and simulate solar thermal systems professionally


The optimization of solar thermal systems depends on many parameters. T*SOL helps to find the best possible combination of storage tanks, heat generators and collector areas. As control also has a major impact on efficiency, you can precisely set control parameters such as switching temperatures and sensor heights. The minute-by-minute simulation enables you to establish the solar yield as well as the exact requirments of the appliances.


Licensing and pricing


System requirements and release notes

System requirements

  • Internet connection
  • Processor: Intel i3, AMD Ryzen 3 or higher
  • RAM: 4 GB
  • Hard disk space: 1,1 GB
  • Resolution display: at least 1.280 x 768 pixels
  • Operating system: Windows 10 (64 bit, latest service pack required), Windows 11 (64 bit)
  • Graphics: 2 GB, OpenGL
  • Others: Microsoft .Net Framework 4.7.2 Redistributable Package

You can download our free trial version and test whether T*SOL can be run on your computer!

Release Notes

November 28th 2023T*SOL 2023 Release 2

The following new features and changes are included:

  • The database was updated.

The following bugs have been fixed:

  • In some cases, the solar irradiation used in the design assistant was too low.
  • In some cases, too large storage volumes were suggested in the design assistant.
July 05th 2023T*SOL 2023 Release 1

The following new features and changes are included:

  • MeteoSyn:
    • New climate data for Germany (Valentin Software TMY procedure with DWD data as basis, 1995 – 2012).
    • SolarAnywhere as additional climate data provider.
    • Revised Meteosyn interface in the "Generate climate data for new location" dialog.
    • Improvement of the location search in Meteosyn.
    • Check of the MeteoSyn database in four phases:
      • Checking the files and database entries for invalid data or data with reduced quality.
      • Search for duplicates in WBV files.
      • Search for duplicates in database entries.
      • Search for imports and updates.
  • The database was updated.

The following bugs have been fixed:

  • Design assistant:
    • Tank volume was 0 m³.
    • Boiler output and space heating buffer tank were not always transferred to the system.
    • Tank volume and tank name were displayed incorrectly under certain circumstances.
    • Tank could not be set back to default tank.
  • In system A14 the tank selection was empty.
  • Sometimes it was not possible to switch to other windows and programs when an editing window was opened in T*SOL.
February 24th 2022T*SOL 2021 Release 4

The following new features and changes are included:

  • New climate data:
    • Meteonorm 8.1
    • PVGIS
    • Solcast
  • The project report is now also available in Russian.
  • The database was updated.

The following bugs have been fixed:

  • The calculation of the rated power of the thermal collectors was wrong and approximately 10 % too high.
August 24th 2021T*SOL 2021 Release 3

The following bugs have been fixed:

  • The calculation of the installed collector power was faulty.
August 19th 2021T*SOL 2021 Release 2

The following features and fixes are included:

  • The collector power is now calculated according to the specifications of the SPF Institute for Solar Technology.
  • The filter of the system selection has been revised.

The following bugs have been fixed:

  • In some system schemes, no storage tanks could be selected.
  • After changes of the specifications (DHW, Space Heating, Location) not all variants were simulated in the variant comparison.
March 24th 2021T*SOL 2021 Release 1

The following features and fixes are included:

  • Updated water tanks of well-known manufacturers.
  • Updated climate data based on Meteonorm 7.3.
  • Updated databases.

The following bugs have been fixed:

  • If climate data were changed then they were not adopted in all variants.
  • The name of the climate data was unintentionally changed if a climate data record was set as default.
  • In some cases the arrow keys were no longer displayed in the component dialog.
  • Climate data were not saved in the project.
  • Images too small in the project report.
  • Error in calculating the distance between collectors.
  • Some manufacturer systems could not be loaded.