Sundra 5-16 solar collector - Seido 5 Evacuated Tube

The Seido5 solar collecting tube contains a convex absorber plate encases in a 100 mm x 2000 mm vacuum tube. Originally developed for thermal control in satellites, the heat pipe vacuum tube absorbs up to 92% of the incoming irradiation.

Sunlight heats the dark blue absorber plates that transfer their heat to a heat pipe in the middle of the glass tube. The heat pipe consists of two meters of copper tubing with an evaporator section, a capillary wick structure, a condenser section and a small amount of vaporizable water. The evaporator section is tightly bonded to the absorber plate, where it captures the heat from the absorber and evaporates the water. The evaporated water moves up to the condenser section. The condenser protrudes out from the evacuated tube and is inserted into the heat exchanger manifold. Here, the water vapor is cooled and condensed into liquid form, transferring its heat to the fluid flowing through the manifold (anti-freeze, in our case). The liquid water is then pulled down the tube by gravity and this cycle begins again.

The lifespan of the tube is determined by how well the vacuum remains sealed. With wear, the seal breaks down and the system becomes less and less efficient over time. However, an inefficient tube will still produce hot waterallowing you to keep it past its estimated 10 year life. Moreover, modular nature of the tubes allows you to replace the tubes one at a time and with relative ease.

Technical Specifications

Type	SEIDO5
Specification	Heat pipe vacuum tube with bent absorber
Configuration
Absorber area	0.225 m²
Weight	4.7 kg
Installation tilt angel	35° – 90°
Dimension	Ø100mm x 2000mm
Collect heat pipe	Heat pipe copper Ø 8 mm
Absorber material	Copper- Aluminium sunstrip, 0.47 mm thickness
Selective coating	Aluminum nitride Al-N-O selective coating; Absorptance: a > 0.92; Emittance: e <>
Glass tube material	Borosilicate glass Thickness: 2.5 mm Transmittance of glass: 91%
Vacuum	<>
Min. ambient tem.	-45°C
Stagnation temp.	247°C
Resistance to hail	Ø35mm

Source: Sundra SEIDO5 series Heat Pipe Vacuum Tube Solar Collector