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The Energy Experts Say

Transpired solar collectors are not an invention - they are a "a law of nature". Done correctly they cannot not work.

The Fabric Transpired solar collector and Solarwall collectors work the same. Both flavors are tested using the same protocols and procedures.


The simplicity, elegance and scientific acknowledgements of the original transpired solar collector, Solarwall cannot be over-stated. The American Society of Mechanical Engineers authored a book and created a museum to substantiate this fact. In 2014 they titled a book,


"Engineering the Everyday and Extraordinary, Milestones in Innovation"

In the category of “Energy Innovations” the ASME authors picked 9 energy/power technologies, from the past 200 years. They are:


Jet Engine | Incandescent Light Bulb | Itaipu Dam | Transformer | SolarWall | Electric Generators | Internal Combustion Engine | Alta Wind Energy Center | Steam Engine


Now please, re-read the list. This is an extraordinary statement about the transpired solar collector. And now you have the ability to be a part of bringing this technology to the market place after you have taken Sunreps training.

Dr. Charles Kutscher and Dr. Craig Christensen

NREL scientists who invented the fabric transpired solar collector

How the Solar Plenum works

  • 1. Solar Preheat Mode (≤ 54°F)

    When outdoor air is 54°F or colder (or below the RTU’s free-cooling setpoint), the plenum's actuator damper remains closed. The system delivers preheated air from the solar collector directly into the RTU economizer hood.

  • 2. Transition Mode (55–60°F)

    Actuator arm starts opening the plenum damper at 55 F. to allow ambient in and starts shutting off the solar. At 60 F the plenum damper restricts solar air while allowing 100% ambient air to enter the RTU.

  • Service Access

    HVAC techs can remove the solar plenum as easily as removing the standard RTU leaf guard filter —because the filter is incorporated into the plenum.

Transpired Collector Principle

  • While the building is occupied, the RTU fan continuously pulls in fresh air — creating constant airflow from the collectors to the rooftop unit.
  • Sunlight heats the black absorber surface of the collector.
  • A thin boundary layer of warm air (1–3 mm thick) forms on the surface.
  • That solar-heated air is immediately drawn through the absorber's perforations before it can escape, delivering warm, preheated air directly into the HVAC system.
  • When 100% ambient air is needed for momentary "air conditioning" the pressure relief panel opens allowing for 100% volume of air to enter the intake hood.