The UVAC 90-7G is our first large aparterture trough receiver. Based on the RS-UVAC 70-7G technology, this large diameter receiver enables more energy absorption, hence increasing the energy output per unit.

The UVAC 90-7G has been developed by Rioglass based on more than 20 years of proven track record of developing HCEs for the solar thermal industry by Solel.

The UVAC tubes are built and tested for extreme environmental conditions and complies with strict standards and quality for Power Piping as well as for Boiler & Pressure vessel (e.g.: ASME B31.1, ASME VIII)

RIOGLASS RS-UVAC 70-7G benefits at a glance:

  • Extremely high solar absorption
  • Reduced heat losses
  • Larger active area
  • Increased thermal heat production
  • No fluorescent phenomena
  • Long-term hydrogen prevention
  • Based on over 20-years of field-proven experience


The Rioglass UVAC 90-7G heat transfer fluid (HTF) receiver is part of our sixth generation of technologically advanced vacuum tubes. This tube was designed and built based on the technology used by the UVAC 6G model.

Using the most state-of-the-art HCE designs and concepts, Rioglass Solar has made the UVAC 90-7G a trusted solar energy application component, employed by concentrated solar power plants (CSP) around the world.

All Rioglass HCE tubes are built and tested to withstand extreme environmental conditions and comply with strict quality standards for Power Piping as well as for Boiler & Pressure vessels (e.g., ASME B31.1 and ASME VIII).


Stainless steel tube:

  • Length: 4,061mm, ±1mm
  • Outer diameter: 88.9mm, ±0.38mm
  • Wall thickness: 2.5mm, ±0.25mm
  • Selective coating at THTF (HTF temperature): 20℃
  • Coating technique: sputtered, selective
  • Average solar absorptance by spectrophotometer after annealing (according to ASTM G173): α ≥ 96.2%
  • Emissivity Factor (by FTIR): ε≤ 9.5% at temperature 400˚C

Glass tube:

  • Outer diameter (Borosilicate A.R.): 135mm, ±1.8mm
  • Wall thickness: 3mm, ±0.5mm
  • Means solar transmittance along 100% of the glass envelope (Air Mass 1.5 according to ASTM G173): τ ≥ 96.4%
  • Active area (bellow shadowing) at THTF of 350℃: ≥ 96.4% of bulk length
  • Number of bellow convolutions: 3
  • Net weight (without HTF): 34 kg
  • Maximum absolute design pressure (at 350˚C): 40 bar
  • Vacuum pressure: ≤ 10-4 mbar
  • Getter Hydrogen absorber: Designed for 25 years product lifetime
  • Design for maximum HTF temperature of 400°C (450°C for 10% of the accumulative operation time)


The RS-UVAC 90-7G Components:

  1. Coated Stainless Steel Absorber tube
  2. Coated Glass Sleeve Enclosure
  3. Glass to Metal Joints
  4. Bellows
  5. Getter & Barium Getters
  6. External shields
  7. Internal shield