The thermosiphon system consists of 2 concentric tubes of borosilicate glass. These tubes exist between a pressure below 0,001 atmospheres. When the tubes are manufactured in vacuum, the air within the space between the two tubes is removed, thus minimizing heat losses by conduction and convection.


Solar radiation passes through the glass outer tube, strikes the absorber tube and is converted into heat. The heat transfer fluid that flows in the tube is heated and transfers to the top of the collector, which is where the liquid primarily circulates. These sensors allow to heat the circulating fluid at elevated temperatures, which offers the use of heat distribution systems in conventional water heating applications. The vacuum tube collector remains more constant with variations in temperature or in the incidence of solar radiation.


Advantages of vacuum tube collectors over conventional flat collectors

The difference between the technology applied to flat plate collectors and the vacuum tube consists essentially in insulation: in the flat-plate collectors there are losses by convection, while in the tubes, being isolated in a vacuum, these losses are reduced to values of up to 35% less compared to flat panels, which allows for dramatically increased performance.


Vacuum tubes, compared with flat plate collectors, represent an advance in heat gain under unfavorable conditions (just when you most need the heat).


An added advantage of the tube is its major versatility in placement, both from the practical point of view and aesthetic, as being cylindrical, it tolerate variations on the ideal angle without loss of performance making them suitable for the vast majority of existing buildings. To this we must add that tubes need less surface area.


Other advantages of vacuum tubes:

  • Maximimizes the use of diffused light, optimizing performance and enabling the days of faint cloudiness to continue warming with a good yield.

  • The cylindrical shape of the tubes allow greater use of solar hours, appropriately taking advantage of solar radiation from early morning until late afternoon.

  • Simple to assemble, therefore reducing the cost of installation labor and future repairs. It is possible to install or repair this and compact systems with just one single installer, without using extra staff and expensive elevators or cranes.

  • Low wind resistance thanks to its cylindrical geometry avoiding complicated mounting structures and problems of anchorage covers.

  • Greater impact resistance. Due to the curvature of the glass tube, passing tests equivalent to a ball of hail up to 25 mm in diameter.

  • Low wind resistance thanks to its cylindrical geometry avoiding complicated mounting structures and problems of anchorage covers.

  • Given the low emissivity (90 %) and vacuum insulation, these high yields have not been overcome in the field of solar thermal energy.










  • The vacuum tube is concentric to 360º degrees, thereby providing a complete capturing of solar rays in the first rays of sunshine of the morning until late afternoon. Even the back of the tube absorbs direct radiation and diffuses through the metal reflector of the collector. The result is a captured energy field throughout the life of the collector.


  • A flat collector provides a total capture only once a day, usually at noon. In the morning and afternoon, the sun's rays hit perpendicular on the collector and the energy absorbed is less.


Technical Data



Concentric double-layer tube with  vacuum and selective coating AL-N/AL



Borosilicate glass 3.3


Transmission in the tube

≥ 91 %


Exterior diameter

Ø 47 mm


Exterior length

1500 mm


Exterior thickness

1.8 mm


Interior diameter

Ø 47 mm


Interior thickness

1.6 mm


Thermal expansion

3.3x10-6 K


Hail resistance

Up to 25 mm in diameter


Frost resistance

- 35º C


Wind resistance

+ 30 m/s



Vacuum (P < 0.005 Pa)



0.8 W/m2 (80º C)



Silicone: UV stabilized and resistant to high temperatures

Absorber in the tubes

Absorber material

Cu/AL/SS/N2 over borosilicate glass 3.3


Selective coating

Triple coat: ALN/SS-ALN/Cu


Absorption coeficient α

≥ 94 % (AM 1.5)


Emission coeficient ε

≤ 7 % (80º C)

Transfer sheet





2 mm



1.2 kg






  • 001001
  • 004004
  • 005005
  • 011011
  • 012012
  • 013013
  • 014014
  • 015015



Our manufacturing plants have been prepared in accordance with the ISO 9001:2008, in terms of Quality Management Systems.


Our manufacturing plants have been prepared in accordance with the ISO 14001:2004, in terms of Environmental Management System.


Our manufacturing plants have been prepared in accordance with the OHSAS 18001:2007, in terms of Occupational Health and Safety Management Systems.


We have a quality control divided into three elements:

  • Regular inspections allow us to guarantee the quality of the raw material.

  • Quality control in the process of our manufacturing procedures.

  • Quality control of finished products, we conduct through inspections and tests of reliability and performance.

The solar vacuum tubes from Solar Innnova have passed several international certification requirements and continue to improve the quality and performance of our products of proven technologies. Quality is one of our core principles and the pursuit of quality is the engine of the company's future, in their desire to continually offer better products.


Our solar vacuum tubes are certified by internationally recognized laboratories and are proof of our strict adherence to international safety standards, long term performance and overall quality of products.


ISO 9001:2008





ISO 14001:2004





Defectos de Fabricación

  • 10 years.




Container 20’


Container 40’



Technical Data Sheets