Solar Attic Fans

Is it worthwhile to use Solar Attic Fans in Michigan? We are getting conflicting reports, from not enough sun in MI to they pull air from nearby can vents vs. soffits so not as effective; then there is the ‘we never install a new roof without them’. Help!

Would like an unbiased (someone not trying to sell me something) opinion…thank you.

I have never installed any fans.Most homes can be vented with soffit intake,and full ridge vents.I have done a ton of homes that had solid soffit,and I pull down wood soffits,install vented vinyl soffit,and aluminum fascia.
I did however have a case where I recommended intake booster fan,but H.O. had limited funds, so it never happened.
The only thing I can say is your local roofing companies know your area, and intake booster is less expensive than soffit and fascia job.Not to mention roofers do roofing not soffit and fascia work typically.

Power vents are fine for exhausting an attic, just be sure all other vents open for exhaust are closed. Intake air at the eaves should be clear of insulation and baffled if needed. If you don’t have vented soffit for the fan to draw from, and you are replacing your roof look into the DCI smart vent. Should cost alot less then reworking soffit. I like ridge vent better then fans unless it is a hip roof. I don’t know about your sun light condition where you live, but I think you should be fine. Another alternative is to use electric.


As soon as it gets light out the fan runs. If it is cloudy the fan runs.

I do not know how you do not have enough sun. Electric fans run only when it gets to a certain temperture. So the electric fan will run less then a solar fan.

The fan will pull from the path of least resistance. If the other roof vents have intake they are drawing from. They will continue to be exhausts vents. If the 2 vents are too close together, then the passive vent will become intake. Most times they will continue to be exhausts. Hot air rises. So it takes a lot to short circut exhaust vents.

I’ve seen on many roofs where the gable vents where left open and ridge vent installed making gables intake. Same with power fans will draw from the nearest opening.Venting top portion only. Very easy to short circuit ventillation.

If you have adequate intake at the soffit, your solar fan will not pull air from the can or gable or ridge vents. … -Myth.html … -Fans.html

yes it will hold a lighter to it and see

Dennis, I like your model. But do smoke and air move the same? Aren’t they chemically different and maybe behave differently?

Thanks for all of the information.

We do have a hip roof. We currently only have 4 cans venting the roof on the hip portion, which is over the main living area (kitchen/living room) where the hip roof is. There are 2 gable vents; front of garage & front of bedroom, though they sit about 12"+ below the peak. Sufficient soffit vents w/baffles. 1750 s.f. house. No cans on other parts of roof; garage/bedrooms. Told to add a minimum of 9 more cans, or switch to ridge venting. The additional cans will be placed in so many different areas due to the roof style that we are not sure how that will look (will be able to see them from both sides as well as the back where the current 4 are). But conflicts as to the effectiveness of ridge venting as well as the ridge venting getting clogged over the years (we have several popular trees nearby).

Maybe the solar attic fans would reduce the need for too many more cans? One family friend really insists we should go to ridge venting…thoughts?

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Just do the fans vented soffit is adequate. Loose the cans.