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


Getting a certified installer to install your solar attic fan may cost you as much as $1000, but you have an option that will cost you less – you could go DIY and do the installation yourself. While the cost of the fan and other materials is unavoidable, you can save $200-$300 or more for every hour the roofer, electrician, and carpenter would have worked.

Before you go DIY, however, you should know you can buy 2 main types of solar attic fans. There is the roof-mounted type, and there is the gable-mounted type. For each of them, the installation processes differ and cannot be interchanged.

At the simplest, installing roof-mounted solar attic fans involves creating a hole between two roof rafters and then fixing the fan into the hole. Gable-mounted solar attic fans, on the other hand, require that you fix solar panels on the roof, fix the fan into a cut hole in the gable, and then connect the panel to the fan.

Tools You Needed for the Attic Fan Installation

  • Reciprocating Saw
  • Hammer
  • Drill
  • Measuring Tape
  • Caulk Gun
  • Wire Strip Pliers
  • Pencil
  • Stud Finder
  • Safety Goggles
  • Utility Knife

Things to Know Before Installing Your Solar Attic Fans

You Must Earth the Solar Attic Fan

Some parts of a solar attic fan are made of metals to conduct external electricity. Since the installation will be on or close to your roof, the solar attic fans may get struck by lightning. If this happens, they most probably will get damaged. To avoid this, ensure the solar attic fans come with a grounding or earthing wire and connect this wire correctly.

Earthing your solar attic fan is pretty straightforward but very vital.

Site of Installation

The site in which you install your solar attic fans is vital to how they operate. For the best outcome, ensure the installation is done in the direction where they receive maximum solar power.

Since the USA is within the northern hemisphere, most of the sunlight comes from the south. So, the best spot to install your solar attic fans is on the roof slopes facing the south. If this is not feasible, get solar attic fans with panels you can tilt.

This way, you can install the fan on the west- or east-facing roof slopes and then tilt the south’s solar panel.

Besides the direction of sunlight, you should consider the best position for efficient ventilation. With a soffit vent, a solar fan installation at the center makes for a better cool air flow.

Ensure You Have an Intake Vent

Solar attic fans promote attic ventilation by pumping hot air out of the attic. When they do this, they create negative pressure in the attic, which drives cooler air entry.

However, there is no way cool air will get inside the attic without an intake vent (such as soffit vents). Therefore, before installing solar attic fans, put in some soffit vents.

Ensure There Are No Leaks or Cracks in the Attic

Before installing solar fan, ensure the attic is correctly sealed off from the living space. Also, ensure that there are no leaks from outside into the attic.

The presence of leaks from the living space into the attic means the solar attic fans will draw cool air from your house. Consequently, your air conditioning unit will do more work to keep the house cool, and your energy bills may skyrocket.

On the other hand, if there are leaks from the outside into the attic, more heat will seep in. If this happens, you need extra fans to cool the attic sufficiently. So, before installing the fans, ensure the attic is airtight from the living space and the outdoors.

How to Install a Solar Attic Fan Step-by-Step

Roof-Mounted Solar Attic Fans

Step 1

Locate your south-facing roof slopes. This is where you will install the solar attic fan for the panel to receive maximum direct sunlight.

Step 2

Search for the rafters. You can do this using the hammer or the stud finder. When you find two rafters wide enough to hold the mount, mark the rafters and the spot between them using the pencil.

The solar attic fan will be installed between these two rafters while the frame of the mount is drilled into them.

Step 3

Strike a nail through the center of the site where you intend to install the solar attic fan. Then tie a string to the pencil and attach it to the nail.

Place the solar attic fan flushing on the installation spot with the nail still at the center. Then with the pencil attached to the nail, trace out the outline of the inner circle of the flushing.

Step 4

Cut out the tracing using the reciprocating saw. While cutting, ensure you do not cut through the roof rafters. Only cut the roof sheathing in the space between them.

Step 5

Cut a slit at the hole’s 3 and 9 o’clock positions with the utility knife. The slits should be long enough to allow the footprint of the solar attic fan flashing to go under the shingles.

Step 6

Insert the reciprocating saw sideways at the end of the 3 o’clock end of the cut hole. Then proceed clockwise, cut the roofing nails till you get to the end of the 9 o’clock cut hole. With the nails out of the way, nothing should prevent the footprint of the solar attic fan flashing from sliding beneath the shingles.

Step 7

With the caulk gun, apply some caulking material at the base of the flashing. Applying the caulking material in two concentric rings should do.

Step 8

Glide the upper side of the flashing beneath the shingles and the tar. Pull the flashing up until the shingles and the elevated part of the flashing touch each other.

In all of this, the lower side of the flashing should remain outside, on the top of the shingles.

Step 9

Fasten the flashing to the roof through the predrilled screw holes with the provided screws.

Step 10

Apply some caulking materials on the exposed screw heads to provide some protection from the weather. Then caulk the point where the shingles meet the elevated part of the flashing and the slits created in step 5.

Step 11

Adjust the solar panel, raising or lowering it to a position where it will receive enough sunlight.

Gable-Mounted Solar Attic Fans

When fitting gable-mounted solar attic fans, check the slope of your roof. Sloped-roofs need a flush-mount unit for solar panel installation. On the other hand, flat-pitched roofs do not necessarily need a flush-mount unit. They can make do with a weight-mounting system.

Step 1

Locate your south-facing roof slopes. Fitting the panel in this location makes for the reception of maximum sunlight.

Step 2

Following the wiring diagram, strip the wires with the wire-strip plier, then connect them to the solar panel’s junction box accordingly.

The red wire should go into the positive (+ve) terminal, while the black one goes to the negative (-ve) terminal. After connecting the wires, fix the water-tight connector to the junction box. Then tighten it. The water-tight connector serves to keep water out of the box.

Step 3

Secure the panel in the mount, then locate the rafters in the roof using the hammer or stud finder.

Mark the position of the rafters with the pencil, then place the mounts over the markings. Add butyl sealant under each mounting bracket before drilling and screwing them to the rafters.

Step 4

Run the cable from the panel towards the gable area, securing the wire with clips at 18-inch gaps. Then when the cable gets to the gable, run it through the vent.

Once you have successfully installed the solar panel, the next thing to do is install the fan.

Step 5

Choose a site in the gable to mount the fan. Then measure and cut out a brace for the fan. In many cases, the brace size is 2 x 4, so you could go with that measurement once you have cut out the brace, drill it and screw it within the gable opening.

Step 6

Attach the fan to the brace and the proximate gable area using wood screws.

Step 7

Using the plier, the wire passed into the gable vent in step 4. Then connect them to the fan, and ensure you do this correctly. If the wires are disconnected, the fan will suck hot air into the attic instead of removing it.

As highlighted in step 2, the positive wire (red) should go to the positive terminal. Then negative wire (black) should go to the negative terminal.

Step 8

Install the thermostat or temperature controller. To do this, attach a plastic electrical box near the fan. Then run the cable from the panel into the box.

Connect one of the wires from the panel to the thermostat. Then connect the other panel wire to the fan. Finally, connect the unconnected wires of the thermostat and the fan to each other. Then cover the connected wires with a wire nut. Place the thermostat or temperature controller in the box. Then set a threshold temperature for activating the fan.

How Much Does It Cost to Install a Solar Attic Fan?

On average, the installation costs between $450 and $1000 to install a solar attic fan. It all depends on the type of solar-powered attic fan you buy, the cost of materials, and the cost of labor.

To get a roof-mounted solar attic fan, you may spend between $315 and $400. But for a gable-mounted solar fan, you may spend $266 to $350.

The expenses on solar attic fan installation materials include the price of shingles, the price of caulk, and the price of siding. For the shingles, you may spend up to $100 to get a 100-square foot of shingles. You may spend $4 to $6 on caulk and around $100 on the siding.

If you are installing the solar attic fan by yourself, you would not have to worry about labor costs. But you may have to get some tools if you do not have them already. However, if you choose to get a certified installer to do the job, you will pay for labor. For a roof-mounted solar attic fan, you only need a roofer and an electrician.

Depending on the roof type, the roofer will mount the solar attic fans on the roof and charge around $40 to $75 per hour. The electrician, on the other hand, will help you install the solar panels correctly. Electricians charge around $40 to $100 per hour.

For a gable-mounted attic fan, you may also need a carpenter to install the fans for you if there is no space in your gable already. Carpenters charge around $60 to $70 per hour.

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.

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