# DIY Solar Attic Fan Installation – Steps, Tips, and Cost

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## How Many Solar Panel Attic Fans Do I Need for My Attic?

The number of solar attic fans you need for optimal attic ventilation depends on the attic size and the roof’s slope.

Generally, the larger the size of the attic and the steeper the slope of the roof is, the more fans you will need to keep the attic cool.

### How Do I Calculate the Size of My Attic?

1. Sketch your attic on paper. In this sketch, divide the attic into squares and rectangles. If there are triangular areas and areas with irregular shapes, mark them off too.
2. Measure the dimensions of every square and rectangle in the attic in feet. Jot the values down.
3. Calculate the squares and rectangles area by multiplying the value of the dimensions for the squares – length x length, and the rectangles – length x width. Note the products in square footage.
4. Measure the base and vertical height of the triangular areas in feet.
5. Calculate the area of the triangles by multiplying the base by the height then dividing by 2.
6. Sum up the areas of squares, triangles, and rectangles. Then you have the size of your attic in square feet.

### What Is the Slope of My Roof?

The slope of your roof should be indicated in the plan of your house. The value of the slope is expressed in twelfths and can be any value between 1/12 to 12/12.

Generally, a 12/12 roof is very steep, while a 1/12 roof is very shallow.

Once you know the slope of the roof and the attic size, you can determine the number of fans you need to keep the attic cool by following the table below:

The number of solar attic fans recommended in the table above is based on 20-watt fans under regular conditions.

## Final Thoughts on Solar-Powered Attic Fans

For sure, a solar attic fan will make your attic cool and bring down your cooling costs. But the costs of installing one can be quite steep. To this end, you may choose to install the fans by yourself to avoid the huge installation expenses. With the guide we provided above, you should have little or no problem sorting out the connection yourself. But ensure you prioritize safety as you take on this task.