TestLab Solar Thermal Systems

At our TestLab Solar Thermal Systems, we test solar collectors, components and complete systems. In addition, we provide support to our clients in developing their products.
Our test center is authorized by DIN CERTCO and fully accredited by the German Association for Accreditation (DAkkS). We provide services worldwide. Our facilities include a large outdoor test field and our laboratories are equipped with state-of-the-art facilities for carrying out our testing services. Our team of experienced engineers and scientists has already measured and characterized well over 500 collectors and systems.

We look forward to working with you!

On this topic from our research blog »Innovation4E«:

Fully accredited and accepted worldwide: Solar collectors from all over the world are being tested in the TestLab Solar Thermal Systems at Fraunhofer ISE in Freiburg

Blog post by Korbinian Kramer

Dr. Korbinian KramerAccredited testing institutions play a significant role to ensure the quality of solar collectors and other thermal heat generators, such as heat pumps, and to provide transparency on the international market. How a testing institution acts in such an environment and continues to reinvent itself...

Read more on blog.innovation4e.de

Certification paths

  • Solar Keymark® (ISO 9806)
  • SRCC® (ICC 901/SRCC 100)
  • GSCN (Global Solar Certification Network)

Monitoring und in-situ testing

  • Certification and acceptance
  • System and Plant monitoring
  • Data visualisation
  • Customer-specific analyses

Factory Inspections

  • Solar Keymark Factory / Physical Inspections
  • Sampling (also Remote Sampling)

Mechanical load tests

  • Compressive, tensile and thrust load tests
  • Graded load imposition (e.g. unevenly distributed snow load)
  • Variable environmental conditions (-40 to 60 °C)
  • Testing of assembly and fastening systems
    (max. 12 m2 at 6000 Pa)



Collector Testing

We are testing all types of thermal energy converters, including:

  • Solar thermal collectors (FPC, ETC)
  • Photovoltaic thermal collectors (PVT)
  • Solar air collectors (SAHC)
  • Solar air heat exchangers (SAHE)
  • Process heat and concentrating collectors (PTC, LFC, CPC)

Infrastructure and testing methods

  • Indoor – solar simulator for performance and function tests
  • Outdoor – test stands for performance and function test
  • Mobile air collector test stand for performance and function tests (indoor and outdoor)
  • MPP-Tracker of various power classes (PVT)
  • Mobile measuring equipment for system monitoring, performance and function tests
  • Testing according to EN 12975-1 / ISO 9806



Additional Offers

  • Real-ice hail impact test (25 mm, 35 mm, 45 mm)
  • Measurement of optical parameters (absorption, transmittance, emission, reflection)
  • Thermographic investigations
  • Outdoor weathering in different climatic zones
  • Heat pipe performance characterisation
  • Measurement of the shape fidelity of mirrors
  • Determination of heat losses of receivers
  • Long-term monitoring
  • Corrosion testing
  • Customised accelerated ageing testing
  • Ray tracing tests
  • Fluid dynamic simulations
  • Component and system simulation and modelling

Upon request, we are glad to provide a customized offer for you.

Logo Global Solar Certification Network

Contact Press / Media

Sekretariat TestLab Solar Thermal Systems

Office hours: 9-12 Uhr

Fraunhofer ISE
Heidenhofstr. 2
79110 Freiburg

Phone +49 761 4588-5354

Korbinian Kramer

Contact Press / Media

Dr. Korbinian Kramer

TestLab Solar Thermal Systems

Fraunhofer ISE
Heidenhofstr. 2
79110 Freiburg

Phone +49 761 4588-5139

Contact Press / Media

Stefan Mehnert

TestLab Solar Thermal Systems

Fraunhofer ISE
Heidenhofstr. 2
79110 Freiburg

Phone +49 761 4588-5354

Contact Press / Media

Konstantin Geimer

TestLab Solar Thermal Systems

Fraunhofer ISE
Heidenhofstr. 2
79110 Freiburg

Phone +49 761 4588-5354

Team of TestLab Solar Thermal Systems
© Fraunhofer ISE
Team of TestLab Solar Thermal Systems (f.l.t.r.): Christoph Thoma, Korbinian Kramer, Christian Schmidt, Sven Fahr, Arim Schäfer, Stefan Mehnert and Konstantin Geimer.

Selected Projects of the TestLab Solar Thermal Systems



Cost Optimization in Solar Thermal Energy by Means of Standardized Components and Interfaces


SpeedColl 2

Service life estimation for solar-thermal collectors and their components



Development and measurement of novel solar air-heating collectors and investigation of suitable energy usage concepts



Field test with highly efficient vacuum tube air collectors for solar back-up heating

Solar Air Heating Collector Field Calculator and Optimizer for instantaneous Working Points - Aircow

parameter study using “Aircow"
© Fraunhofer ISE
A small parameter study using “Aircow”. Individual diagrams visualize the simulation results.

For covered solar air heating collectors, a thermo-hydraulic curve model was developed and implemented in an Excel tool at Fraunhofer ISE. The core feature is to calculate and optimize air collector field dimensions and mass flows at instantaneous working points in the system context.
The tool is used within the Solar Keymark certification. It converts the thermo-hydraulic air collector parameters in a way that they can be compared to each other and can be used for a simulation of the collector annual output in ScenoCalc.

The Excel tool can also be used to determine the thermo-hydraulic air collector parameters based on measurement results according to EN ISO 9806.
The tool is ready for system planning, which means that collector fields can be dimensioned and results can be used to choose fans. It supports air collector development, and it is conveniently structured for scientific studies.



Important remark: The basis for Aircow is a measurement of the solar air heating collector in closed loop operation according to EN ISO 9806. The results of a measurement in open to ambient operation is not sufficient to be calculated in Aircow. However, open to ambient solar air heating collectors can also be calculated with Aircow if a measurement in closed loop operation was performed according to EN ISO 9806.

Information on validity:
Aircow has been approved for official use by the Solar Keymark Network in January 2017.


Aircow_v3.00.xlsm Format: *.xlsm (MS Excel 2010 or later with macros)
Size: 876.7 kB
Developed by: Christian Welz
Download version 3.00 (2016-09-30)
Aircow_v3.00_Manual.pdf Documentation / manual 53 pages, english
Format: *.pdf
Size: 3.6 MB
  Version history:
See last worksheet of modus "B. System Planning, Scientific Studies" within Aircow