Design tool KOLEKTOR 2.2 for a detailed solar thermal flat-plate collector modelling

Authors: Tomas Matuska, Vladimir Zmrhal


Short outline of KOLEKTOR tool

User-friendly software tool KOLEKTOR has been created in Visual Basic Studio. Detailed geometrical and physical parameters of individual collector elements are entered via tool cards (general, glazing, absorber, frame, calculation and results). Results are collector thermal output and efficiency curve for given temperature range and climatic conditions, stagnation temperature, mean temperatures and heat transfer coefficients at individual collector surfaces). Tool KOLEKTOR is universal for performance modelling in wide range of flat-plate solar collectors esspecially with:

  • different internal air pressure in collector (atmospheric, evacuated collector)
  • different slopes
  • separate installation or building envelope integration (with given thermal resistance)
  • different heat transfer fluids (water, water-glycols mixtures)

The software tool KOLEKTOR 2.2 is oriented esspecially for design and virtual prototyping of new solar flat-plate collectors resulting in efficiency curve determination, for parametric analysis to obtain information on different parameters influence on collector performance and esspecially for investigation of thermal performance of advanced solar collectors (building integrated, evacuated collectors, etc.).

The core of the program, a mathematical model, is based on energy balance of heat flows from absorber surface to ambient environment (outer energy balance of absorber) and to heat transfer fluid (inner energy balance of absorber). Heat transfer calculation (convection, conduction, radiation) in collector and temperature distribution for main collector surfaces (outer glazing surface, inner glazing surface, absorber surface, heat transfer fluid, inner frame surface and outer frame surface) is processed in iteration loops.

More information can be found in mathematical reference handbook.

and in

Matuska, T., Metzger, J., Zmrhal, V.: Design tool KOLEKTOR 2.2 for virtual prototyping of solar flat-plate collectors, Proceedings of Eurosun 2008.



Software tool is developed in Visual Basic.NET platform. To start the tool, the distribution pack for Microsoft NET. Framework has to be installed first.

  1. Download and install Microsoft.NET Framework 3.5
  2. Download pack to Program Files folder and unzip it. Folder Kolektor with installation files will be created.
  3. Start setup.exe and tool KOLEKTOR 2.2 will be installed into your computer and ready for first use. You can find it as an icon in Programs Menu under Kolektor or you can use the setup.exe (previously used for installation) for launching the program.


Note: Local setting of windows using dot in decimal values (e.g. Great Britain) should be used to run KOLEKTOR program.


NOTIFICATION: The tool is under development. Every important change will have a new version number. The comments are welcome on email bellow.


SOLNET course on Solar Thermal Collectors at Universitat des Illes Balears, Palma de Mallorca

Files to download:

Default parameters for solar collector reference example: default.kol

Excel sheet for evaluation of efficiency curve coefficients: evaluation.xls

Solar domestic hot water system – studio file with weather data for TRNSYS in zip file:

Presentation (lecture) in pdf