Performance > Solar Attic Fan Venting Capacity and Sizing Chart
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 |
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.
| 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
| 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
| 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 |
