What material is used for the SPRING panel heat exchanger?


It is important to distinguish between our two generations of SPRING currently available:

  • The SPRING3, with its polymer exchanger, sold from July 2022 in the following versions:

    • SPRING 425 Shingle Black insulated - DSTI425M12-B320SBB7

    • SPRING 425 Shingle Black non-insulated - DSTN425M12-B320SBB7

  • The SPRING4 with its aluminum exchanger, marketed from May 2024 in the following versions:

    • SPRING4 425 TOPCon insulated - DSTI425-108M10TB-03

    • SPRING4 425 TOPCon non-insulated - DSTN425-108M10TB-03

    • SPRING4 425 TOPCon with fins - DSTF425-108M10TB-03

For more details on the specifications of the models, you can refer to the dedicated article:

What material is used for the SPRING panel heat exchanger?



The heat exchanger of the SPRING4 TOPCon solar panel is made of Aluminum, in an alloy specially dedicated to thermal solar panels. We chose this material because it allows a constant operating pressure in the system, and optimal heat exchange with the external environment of the panel, which allows better efficiency in the case of coupling with the evaporator of a heat pump.

It is made up of

  • 304 channels of approximately 3 mm in diameter,

  • Two collectors of diameter 35.4mm which are used to distribute the water in these channels.

This DualSun specific design is protected by international patents.



The heat exchanger of the Spring panels is made of PolyPropylene (more precisely we use a Block-Copolymer).

On the one hand, this material has been designed and tested to last 40 years in solar heating applications, which has been confirmed by a theoretical ageing study carried out by the CNRS PIMM laboratory, as well as by accelerated ageing tests at TÜV Rheinland.

On the other hand, this material has already been used for decades in similar types of applications.

For example, there are already thermal collectors for swimming pool heating that have been using the same material as the DualSun SPRING exchanger for decades. 

That said, the DualSun exchanger is much more protected than a pool heating collector, so its longevity will be greater: 

  • The exchanger is positioned behind the photovoltaic laminate which constitutes a very effective anti-UV barrier (glass, EVA, backsheet, etc.).

  • The temperatures in the DualSun SPRING exchanger are limited by the photovoltaic system, which also recovers energy. The DualSun heat exchanger thus achieves a lower stagnation temperature than the exchanger in full sunlight without PV laminate,

  • Our recommendations on pressure are clear: if the panel does not exceed 1.5 bar in operation it will have an exceptional longevity.

What pressure test are DualSun SPRING panels subjected to before they are installed?

Each DualSun SPRING panel is tested at 1.5 times the maximum allowable operating pressure (see module data sheet in the DualSun documentation area) to verify their tightness.

  • The protocol and test tools are standard and certified in the solar thermal industry.

  • The measurement performed is a measurement of pressure variation in the panel over a given time, which is then converted and communicated as a leakage rate.

  • The pressure variation allowed over the duration of the test corresponds to zero, +/- the detection threshold of the test bench, of the order of one ten thousandth of the atmospheric pressure in the heat exchanger (i.e. a high threshold equivalent to 3ml/min after conversion by PV=nRT in the test).


>To go further : What tests are performed on DualSun SPRING panels at the end of production?