Evacuated Tube Technology

Research and development for the Seido line of evacuated tube using heat pipe technology was designed by the Daimler-Benz Aerospace Group.

An evacuated-tube collector contains several individual glass tubes, each containing an absorber plate bonded to a heat pipe and suspended in a vacuum. The pipe transfers the heat efficiently to a condenser through the top of the tube. The condensers are clamped to heat exchange blocks in a well-insulated manifold. The special coating on the absorber absorbs more than 92% of the arriving radiation, but radiates less than 8% back to the environment.

Heat transfer from the absorber to the fluid circuit is performed by the “heat pipe”. A heat pipe is a closed system, evacuated and charged with a small amount of water before it is sealed. The absorber imparts heat to this water, causing it to evaporate. The steam rises to the upper end of the heat pipe where it transfers heat to the fluid circuit via a metallic conduction bridge. Being a “dry” connection, fluid in the heating circuit does not flow through the collector.

The absorber and heat pipe are mounted in a sealed evacuated glass tube, cutting the heat looses via conduction and convection. The stable vacuum assures that the collector performs at low outside temperatures and protects the absorber against the environment.


Highly efficient vacuum tube collectors are the right choice when top performance is in demand – throughout the entire year. By preventing air circulation (convection), the vacuum provides efficient insulation and simultaneous protection from environmental influences. This offers constant high efficiency. Their maximum attainable temperature of 250°C, makes vacuum tube collectors an excellent option, and desirable to support traditional heating systems.

  • Reduces operational costs
  • Reduces air pollution
  • Offsets greenhouse gases
  • Utilizes renewable energy resources
  • Installs easily
  • Averages a 20 year life span
  • Provides high efficiency heat energy output
  • Offers dual use potential (hot water and air heating)

The Seido evacuated tube solar collectors come in many different types, optimized for different requirements and applications:

Product Certifications

The SRCC (Solar Rating and Certification Corporation) is the key solar collector certifying body for the US and Canada. The Sunda’s solar collectors have been tested in Canada and Florida and has obtained SRCC certification.

The Florida Solar Energy Center (FSEC) was created by the Florida Legislature in 1975 to serve as the state’s energy research institute. The main responsibilities of the center are to conduct research, test and certify solar systems and develop education programs.

The Institut für Solartechnik SPF is part of the Hochschule für Technik Rapperswil HSR. The Institute has been engaged in applied research and development on thermal solar technology since 1981.

Energy Profiles (Seido 1-16)

Energy profiles are provided below. The profile is based on SPF certification for Seido 1-16.

Energy profiles for other cities are available upon request.

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Solar Pump Station

Our available Solar Pump Stations allow for ease of installation, filling, and precise flow control. The pump station allows for connection to the solar collector and to the storage tank within a solar hot water heating system.

Solar Controller

Our available Solar Controllers provide the best control for your solar hot water heating systems. The Resol DeltaSol BS Pro controller has the ability to read the temperatures of the solar collectors and hot water tank, flow through the panels, as well as control the pump in order to optimize the solar system for the highest amount of heat energy gained even during cloudy periods.