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 access
  • Processor: 1.5 GHz Pentium PC
  • RAM: 512 MB
  • Free hard disk space: 820 MB
  • Monitor resolution: at least 1,024 x 768 pixels
  • Operating systems: Windows 8.1, Windows 10
  • Graphics: 64 MB, OpenGL support (Photo Plan)
  • Miscellaneous: Microsoft .Net Framework 4.7.2 Redistributable Package

Release Notes

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.
July 2nd 2020T*SOL 2018 Release 4

The following features and fixes are included:

  • Revised dialog for adopting the target solar fraction when designing the collector array
  • Updated climate data
  • Updated databases
  • The heating limit temperature can now be adjusted in the EnEV calculation

The following bugs have been fixed:

  • In the design assistant the design target for hot water coverage was limited to a maximum of 30%
  • In some cases, the savings in fuel were zero when comparing variants
  • In some cases no company systems could be selected
  • Missing translations added
August 28th 2019T*SOL 2018 Release 3

The following features and fixes are included:

  • Following a change of computer, the serial number can be deactivated and transferred to another computer.
  • Project reports in Dutch.
  • Updated databases.
  • Updated help contents.

The following bugs have been fixed:

  • The circulation in the reference system was not taken into account in EnEV calculations.
  • Heating circuit data in the reference system were not taken into account in EnEV calculations.
  • Fresh water stations and heat exchangers were displayed simultaneously in the same dialogue.
  • The registration was not changeable from inside the program.
  • Tanks were not editable when the program language was set to French or Spanish.
  • Missing translations added.
August 30th 2018T*SOL 2018 Release 2

The following bugs have been fixed:

  • In some systems a solar fraction over 100% was possible.
  • Missing translations added.

Further changes:

  • Updated databases.
May 7th 2018T*SOL 2018 Release 1

The following new features are included:

  • Custom tanks can now be created and saved in the database.
  • MeteoSyn with Meteonorm 7.2.

Further changes:

  • Updated database with new collectors and boilers.