Performance > Solar Attic Fan Venting Capacity and Sizing Chart

Mountain home with solar attic fan

Solar attic fan reduces temperature up to 40 degrees Black solar attic fan installed on home 10 watt roof mounted solar attic fan installed on an steep roof of a cedar shingle home.

How Many Solar Attic Fans Do I Need?

Several factors can affect the amount of attic ventilation a home needs. Variables such as vaulted ceilings, amount of existing venting (soffit, ridge, gable), attic shape, pitch and obstructions must all be taken into account when calculating the amount of attic venting needed. Your Natural Light dealer will determine the correct size unit or units needed for your specific installation. The output chart below reflects the average venting capacity and cfm output for each solar panel size available.

Natural Light Solar Attic Fan Output Chart

Solar Panel Size Venting Capacity CFM Output
10 Watt Model up to 1,200 sf up to 850 cfms
20 Watt Model up to 2,000 sf up to 1,275 cfms
30 Watt Model up to 2,500 sf up to 1,550 cfms
50 Watt Model up to 3,100 sf up to 1,900 cfms
CFM refers to cubic feet of air moved per minute. The higher the cfm number, the greater the capacity to move air.

Solar Attic Fan Residential Unit Estimator

The charts below should be used as a general guideline for how many Solar Attic Fans are needed for residential installations based on square footage and roof pitch. Download Solar Attic Fan Estimator Sheet pdf.

4/12 Roof Pitch diagram
Attic Size Attic Fans Needed
800 sf (1) 10 watt
1,200 sf (1) 10 watt
1,600 sf (2) 10 watt OR
(1) 20 watt
2,000 sf (2) 10 watt OR
(1) 20 watt
2,400 sf (3) 10 watt OR
(2) 20 watt OR
(1) 30 watt
3,000 sf (2) 20 watt OR
(1) 50 watt
8/12 chart
8/12 Roof Pitch diagram
Attic Size Attic Fans Needed
800 sf (1) 10 watt
1,200 sf (2) 10 watt OR
(1) 20 watt
1,600 sf (2) 10 watt OR
(1) 20 watt
2,000 sf (3) 10 watt OR
(2) 20 watt OR
(1) 30 watt
2,400 sf (2) 20 watt OR
(1) 30 watt
3,000 sf (2) 20 watt OR
(1) 50 watt
12/12 Chart
12/12 Roof Pitch diagram
Attic Size Attic Fans Needed
800 sf (2) 10 watt OR
(1) 20 watt
1,200 sf (2) 10 watt OR
(1) 20 watt
1,600 sf (3) 10 watt OR
(2) 20 watt OR
(1) 30 watt
2,000 sf (2) 20 watt OR
(1) 30 watt
2,400 sf (2) 30 watt OR
(1) 50 watt
3,000 sf (3) 20 watt OR
(2) 30 watt
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Our most popular residential model for flat or sloped roofs. Learn more about roof mounted solar attic fans

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Cool your hot garage by adding a solar attic fan garage vent kit. Learn more about garage exhaust vent kit

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Solar attic fans are available in several models for all roofs. More Info About Solar Attic Fan Models