They are made up of rows of parallel, transparent glass tubes. Each tube consists of a glass outer and glass inner tube. The inner tube is covered with a selective coating that absorbs solar energy well but inhibits radiative heat loss. The air is withdrawn ("evacuated") from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss.

Because of the larger proportion of hot water than cold water, cold water flows downward and hot water goes upward.
Water will be heated continuously and the hot water will be kept in the storage tank.
As the tank is higher than the collector and higher than your shower or bath tub the thermosiphon system doesn't need a pump to supply your house with hot water.

• The round shape makes them collect sun rays optimally
• Unlike other types, vacuum solar heaters still provide excellent results on cloudy days: The tubes can absorb the energy of infrared rays that pass through the clouds
• Temperature and wind have less effect on the water temperature than for other types: This is due to the insulating property of the vacuum tubes
• They are absolutely maintenance free

• Different capacities are available: 180/200/240/300 Litres
• They can be connected to water boilers
• Water is heated to 65°C
• They keep water hot for 3 days in the insulated tank
• Outer tank: aluminium with zinc plating
  Inner tank material: stainless steel
• Support frame: steel plated anti-corrosive tube holder
• They have at least 10 year lifetime
• Optional: Back-up electrical system (connection on grid power in case of very cloudy days)