The Low Carbon Partnership

Evacuated Tube Solar Collectors

There is diffuse and direct sunlight in the UK all through the year. Solar panels can absorb this light and convert it into heat. The problem is in the colder months most is lost to the environment. Vacuum is the perfect insulator as heat cannot travel through it. That’s why thermos flasks have a vacuum jacket to keep their contents hot or cold.

Modern evacuated tubes encase the solar absorber in a vacuum coat eliminating the problem of heatloss. This means that the tubes work purely on sunlight and are not affected by the outside temperature.

Evacuated solar heating panelsEvacuated solar heating panels work in cold, cloudy and windy conditions - unfortunately too common in the UK and Ireland. The higher efficiency of evacuated solar heating tubes mean less area is covered on the roof by the solar heating panels - a desirable feature appreciated by most customers.

Having less solar heating panel area on the roof reduces the fluid content of the solar heating system enabling quicker response to solar radiation.

Vacuum is the best possible insulation for a solar heating panel. It safeguards the collector from moisture, condensation and pollutants - resulting in improved durability and all-year-round performance.

Summary of advantages of the Thermomax  vacuum tube

  1. High efficiency even at low light intensities (e.g. cloudy days)
  2. Ability to achieve high temperatures
  3. The solar heating panels are easy to install due to its lightweight design
  4. Improved aesthetics - Modern and elegant design
  5. Covers less roof area - Less visually intrusive
  6. Durable – Tried and tested for over 25 years, the evacuated tube collectors continue to maintain their vacuum and effectiveness
  7. Each tube on the solar heating panel is individually replaceable allowing for easy repair in case of damage.
  8. Longer life span providing an improved return on investment
  9. Local Manufacture and support _ Thermomax is manufactured in Bangor in Northern Ireland and Blackwood in South Wales.

Download Thermomax brochure

Thermomax Collectors
Thermomax with is part of Kingspan Group PLC is the only evacuated tube registered with the Low Carbon Building Program Phase 2. Thermomax is one of the oldest solar companies in the world and has won many awards throughout the twenty five years is has been in existence.

Direct Flow Solar Collectors
A direct flow solar collector consists of a row or solar tubes and a highly insulated manifold. Heat transfer fluid is circulated in a coaxial manner through the manifold and tubes. The are two panel sizes, 20 tubes (2m2) and 30 tubes (3m2).


  • Unique “plug and play” design of Thermomax solar collectors provides fast and simple installation.
  • Usually installed facing south or east/west, and fixed to the roof using easy fit brackets.
  • Designed for flexible building integration:
installed on sloping roofs, flat roofs or facades
Can be installed on sloping roofs, flat roofs or facades.
Individual tubes can be angled up to 20 degrees
Individual tubes can be angled up to 20° to achieve best performance for building orientation.

  • There is no need for heavy lifting equipment as tubes can be carried onto the roof individually
Model Df100-2M2
Number of tubes 20
Dimensions (gross) (mm) 1996 x 1418 x 97
Aperture Area [m2] 2.153
Weight (kg) 54.8
Fluid Content [Ltr] 3.8
Max. Operating Pressure [bar] 8
Flow Rate [l/min/tube] 0.10-0.25
Vacuum level [mbar] 10-5
Glass Specification Low Iron Solar Glass
Efficiency (Absorber) n0 0.830
a1 [W/m2K] 1.53
a2 [W/m2K2] 0.0063
Heat Capacity [KJ/m2/K] 9.3
Test/Approval (Solarkeymark) EN12975-2
Manufacturers datasheet
Model DF100-3M2
Number of tubes 30
Dimensions (gross) (mm) 1996 x 2127 x 97
Aperture Area [m2] 3.228
Weight (kg) 81.4
Fluid Content [Ltr] 5.6
Max. Operating Pressure [bar] 8
Flow Rate [l/min/tube] 0.10-0.25
Vacuum level [mbar] 10-5
Glass Specification Low Iron Solar Glass
Efficiency (Absorber) n0 0.832
a1 [W/m2K] 1.14
a2 [W/m2K2] 0.0144
Heat Capacity [KJ/m2/K] 9.2
Test/Approval (Solarkeymark) EN12975-2
Manufacturers datasheet


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