SEIDO2 series Direct Flow Vacuum Tube Solar Collector

Higher efficiency
Direct flow heat transfer
High vacuum with long-term stability
Flexible installation angle

Elegant design for aesthetic appearance
Reliability and durability
Easy integration into buildings

The SEIDO2 series collector module is a kind of direct flow solar collector, which system consists of vacuum tube, inner tube of vacuum tube, manifold and inner manifold. The inner tube is connected with the inner manifold and the vacuum tube. The heat-transfer fluid flows through the inner manifold, inner tube, vacuum tube and manifold in turn. The effective heating position is the space between inner tube and vacuum tube. This system allows any installation angle of the module between 0° and 90° allowing the absorber surface being adjusted to the optimum position towards the sun.

Technical data

Module type



Tube construction

SEIDO2---Direct flow vacuum tube with flat absorber


EN 12975

Angle of inclination

0 ° to 90 °

Number of collector tubes



Absorber area

1.39 m²

2.77 m²

Aperture area

1.47 m²

2.93 m²

Gross area

2.04 m²

4.08 m²

Length x width x height (mm)

2126x960 x150



50 kg

100 kg

Efficiency curve

Pressure drop per module

<7 mbar (100L/h)

<20 mbar (200L/h)

<7 mbar (100L/h)

<20 mbar (200L/h)

Fluid content per module

1.3 L

2.6 L

1.3 L

2.6 L

Glass material

Borosilicate glass

Glass tube diameter


Wall thickness




High vacuum, long-term stability

<10-5 mbar

Absorber material


Selective coating

Aluminium nitride





Header box material


Header box size






Polyurethane foam

Max. Operating pressure

6 bar

Stagnation temperature, module


Stagnation temperature, pipe


Assembling components

Stainless steel vertical supports and bottom supports, aluminum header box, 30 mm thickness polyurethane insulation


Compression fitting , 22mm


Customization and convenience

SEIDO2 solar collectors apply direct-flow which even increases their efficiency. The heat transfer fluid in the concentric tubes of the absorber transfers the heat. All SEIDO2 collector tubes are connected in parallel. This allows any arrangement of the module at tilt angles between 0° and 90° with the absorber surface adjusted to the optimum angle. Each tube can individually be arranged to the optimum position towards the sun to receive the maximum solar irradiation throughout the year. Due to these characteristics, the collectors can meet special customer demands as integration into facades or horizontal installations on flat roofs.

Top performance and versatility

An important asset of SEIDO2 solar collectors is their versatility. One of the application areas for SEIDO2 solar collectors is domestic water heating. Therefore, installation requires remarkably little space making it practically applicable at any domestic place. Despite their little size, the collectors still cover over 70% of the hot water needs of an average household. Their excellent efficiency makes them also suitable for the operation of larger systems for commercial or public use. In addition, SEIDO2 solar collectors are also applicable for space heating and air-conditioning.

A circuit and a system

A self-contained heating circuit transports the heat from the collector to the inhouse hot-water storage tank (approx.300L). There the heat is passed on to the inhouse hot-water storage tank by a heat exchanger and the water for domestic use is heated. When the heat supplied by the collector is not sufficient to attain the desired temperature, a conventional heating system takes over and completes the heating process. An electronic control unit (different-temperature regulator) constantly checks whether the temperature at the collector opening is greater than the temperature in the inhouse hot-water storage tank. If this is the case, the control unit switches on the heating circuit.