Solar Thermal Air Collectors: What they are and why they matter!

The clean energy industry is constantly growing. As demand grows for clean alternatives to fossil fuels, there is a rising focus on hydro, wind, solar, and nuclear power alternatives. Using clean energy has financial benefits for the industry and individual households. Additionally, clean energy helps reduce pollution, furthering the promise of a healthier future for all Canadians. With hydro leading Canada’s clean energy sector, there are many opportunities for wind and solar energy to expand. The evolution of solar energy continues to create opportunities for research and development into related technologies. Canada leads the global field in one of these categories: solar thermal air collector development.

For more in-depth information, check out the in-depth article by Brooke Cupelli at Solar Thermal Air Collectors: Form, Function, and Current Capacities in Canada.

So, What are Solar Thermal Air Collectors? 

Like traditional solar panels, solar thermal air collectors capture sunlight and convert that sunlight into energy. Unlike traditional solar panels, which conduct electricity by utilizing photovoltaic cells, solar air collectors use fan mechanisms to harness the solar energy gathered and circulate air to generate heat. Generally, solar air collectors operate in four steps. 

• Step one: The solar air collector captures and absorbs sunlight.

• Step two: The sunlight gets transferred into heat, heating the air within the collector. 

• Step three: Air circulates the heat to move it out of the collector using a fan mechanism. 

• Step four: The energy in the form of heat becomes outputted air. 

Installing solar air collectors vertically on a south-facing wall is most efficient and successful. Vertical installation allows the dark absorber plate to collect as much solar energy as possible, including lower light times (ex. winter). Heating, drying, and building energy stores are the most frequent functions of solar air collectors.

Three Main Types of Solar Thermal Air Collectors 

Solar air collectors can be categorized into three different types: the flat-plate solar air collector, the evacuated tube solar air collector, and the concentrated solar air collector.

Flat-plate solar air collectors have a plastic or an untreated/ exposed metal plate. These collectors have the lowest temperature applications, but the highest usage in Canada. 97% of solar air collectors in Canada are flat-plate collectors. These collectors are most commonly used for heating residential pools, as well as heating commercial buildings.

Evacuated tube solar air collectors come in two variations. One is a flat-plate collector with a coated absorber plate (glazing) or a glass cover over the plate. The other variation has multiple glass tubes running the length of the device, where the internal structure of the tube is the absorber. With midrange temperature production, evacuated tube collectors are suitable for domestic water and space heating/ cooling.

Concentrated solar air collectors use mirrors or lenses to focus the sunlight on a smaller surface area, allowing them to have the highest temperature application. These collectors execute more complicated applications such as industrial process heat, absorption cooling, and steam generation.

 A Future Powered by Solar Energy 

CanmetENERGY is responsible for the majority of Canada’s research and development of solar thermal technologies. With many research efforts looking at how to add more solar energy to Canada’s power grid, the solar energy sector will continue to grow. In 2022, solar electricity accounted for less than 1% of Canada’s total electricity production. There is great potential in the solar energy sector, especially in the production of stored energy. Solar thermal air collectors can help in the continued transition to clean and sustainable energy, positively powering our collective future. 

References

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2. Canada (Natural Resources). (2024, December 20). About Renewable Energy Canada. Natural Resources Canada. https://natural-resources.canada.ca/energy-sources/renewable-energy/about-renewable-energy-canada 

3. Canada (Natural Resources). (2025, May 7). Solar Thermal. Natural Resources Canada. https://natural-resources.canada.ca/energy-sources/renewable-energy/solar-thermal 

4. Canada (Services). (2025, March 14). Canada’s Clean Electricity Future. Canada.ca. https://www.canada.ca/en/services/environment/weather/climatechange/climate-plan/clean-electricity.html 

5. Ikem, I., Ibeh, M., & John, U. (2017, January). Estimating the efficiency of okra drying mixed-mode solar dryer. International Journal of Engineering Research. 6. 250. 10.5958/2319-6890.2017.00013.7.

6. Mund, C., Kumar Rathore, S., & Kumar Sahoo, R. (2021, September 25). A review of solar air collectors about various modifications for performance enhancement. ScienceDirect. https://doi.org/10.1016/j.solener.2021.08.040 

7. Zhang, J., & Zhu, T. (2022, November 18). Systematic review of solar air collector technologies: Performance evaluation, structure design and application analysis. ScienceDirect. https://doi.org/10.1016/j.seta.2022.102885