Preheating of Fresh Air : Calento SL

Calento SL : Solar Heating of Outside Air

The solar air collector Calento SL uses a surface that has a very low emissivity (3% versus the 95% for black paint) for an optimal heating of the air. Thanks to its certified maximum efficiency of 90.1%*, the Calento SL enables the air to be heated up to a maximum of 50°C above the ambient temperature.

Always being connected to a heating or ventilation system, the Calento SL can be applied to a multitude of HVAC system configurations to generate tangible energy savings, year after year, over several decades.

 How the Solar Collector Works 

General function
Operation with Different HVAC Configurations
Connected to a Make up
Connected to a rooftop unit
Connected to stand-alone system
Air to water heat pump assistance
Air-source heat pump assistance
Connected to dessicant or heat recovery wheel regeneration
Cooling with Collectors
Self-cooling in summer time
Nighttime sub-cooling
Collector Manufacturing
Collector manufacturing

Technical Data

Technical Sheet

Calento SLSI Units [IP Units]
Technical Data
Solar air collector typetranspired, open loop, unglazed
Working fluidair only
Main use and purposePreheating of outdoor air
Peak solar efficiency, rated90.1%
Maximum power output901 W/m2 [285 BTU/hr per ft2]
Maximal air throughflow per collector surface185 m3/h per m2 [10 pcm/ft2]
Pressure drop @ maximum throughflow125 Pa [0.5 in H2O]
Maximum temperature rise above ambient50 °C [90 °F]
RETScreen simulation model performance factor1.35
Absorber panel
Panel materialAluminum alloy 99.8, Temper H18
Absorber panel thickness0.7 mm [0.028 in]
Panel surface treatmentHighly selective VDP coating
Available colors, selectiveblue, black
Absorbtivity in thermal spectrum94%
Emissivity in thermal spectrum≤3%
Panel porosity1-4%
Mounted collector system, on site
Plenum cavity depth, standard10 to 20 cm [4 to 8 in]
Framing parts, steel1.31 mm [18 ga]
Weight per surface area, including framing5 kg/m2 [2 lbs/ft2]
Maintenance requirementnone
Freeze protectionunnecessary
Overheating protectionunnecessary
Ratings & certifications
Solar Rating Certification Corp. certificate noSRCC 10002111
Solar Keymark certificate no.011-7S3104 L
Test laboratoryFraunhofer ISE, Germany

Efficiency Curve of the Solar Collector

More details


Over the years, Trigo has developed a series of surface finishes, perforation patterns and profiles to maximize the thermal output the Calento SL series and answer the most stringent needs of engineers and architects.

For engineers, rated performances allow for a maximum temperature increase of 50°C above ambient, regardless of exterior temperature or time of the year. This enables the integration of the Calento SL in applications like outside air preheating, space heating, heat pump assistance, drying, dessicant wheel regeneration, process heat and any application where warm air is needed.

For architects, selective colors include blue (the natural optical outcome of our vapor deposition process) and black, which was created specifically for building integration. Three different perforation patterns are available, as well as four different standard profiles. For special projects, a further selection of about 20 profiles is available. We exclusively use aluminum as substrate material for its superior thermal conductivity and properties against corrosion, as perforations cause the metal to be exposed.

Installation Videos (In French)

Project Photos