Last Updated: Jul 10, 2021
For many homeowners, an attic is a place that is best avoided if at all possible. They are usually hot and muggy during the summer and unbearably cold during the winter. Unless you have a population of birds that take up residence in the attic, most folks are content to only open their attic door once a year to bring down the Christmas decorations.
What few people realize, however, is that proper attic ventilation can play a major role in making your home more livable, resilient, and durable. Solar attic fans are a great way to benefit from the advantages of a properly ventilated attic without running up your utility bills with an electric fan that runs 24/7.
In many homes, attics are uninsulated, unheated, and not air-conditioned. Outside of storage, most homeowners rarely use their attic. A properly working attic fan can help to actively cool the attic space during those hot summer months. While attic vents (which are mandated by almost all building codes) only allow air to flow through, attic fans will actively pull away from the stuffy, humid, and hot air out of the attic. This subsequently creates a negative pressure that draws in cooler and fresher air into the attic space.
Whereas HRV or ERV systems are designed to help airtight homes gain access to fresh air and thus improve indoor air quality, attic fans are focused on helping regulate the temperature of the attic which subsequently affects the thermal performance of the house below. Proper attic ventilation is an important aspect of an energy-efficient home, as a cooler attic in the summertime will naturally lower the temperature in your home as well.
Improperly ventilated attics can lead to the accumulation of moisture that can subsequently cause mold growth and even rotting of the wood holding up your roof. In areas with long, warm, and humid summers, an attic fan will most likely extend the lifespan of your roof and help you to avoid costly repairs. Also, large temperature imbalances between the inside of the attic and outside temperatures during the winter can lead to roof problems and/or issues of ice buildup.
Solar Attic Fans incorporate a small solar panel that powers an attic fan, strategically placed to pull out hot and humid air in the summer months. Solar attic fans will work with the existing passive vents in your attic, meaning that there won't be any hidden expenses related to opening up new ducts or vents in your attic walls. When placed strategically at the ridge of the roof, a solar attic fan will pull air in from the outside, move that air through the attic space before it eventually exits through the venting system.
A solar attic fan is best incorporated into a home where the central air conditioning does not circulate into the attic area. If your home has a whole house fan, an attic fan is not necessary.
Electric attic fans are certainly less expensive than their solar counterparts. However, these fans generally use large amounts of electricity and will add to your monthly utility bill—and the point of an attic fan is to decrease your utility bill. Indeed, studies have shown that while attic fans can decrease air conditioning costs, the amount of electricity it takes to run the fans can more than offset the savings.
To compare the costs, we look at upfront costs and operating costs. A typical 250-watt electric attic fan might cost you around $325, plus another $100 to $150 to have an electrician install the fan. Operating the fan would use around 180 kWh per month if run 24/7 (most likely necessary in areas with hot summers). If the average price of electricity in your region is $0.15 per kWh, you´re looking at an extra $27 dollars per month, or $162 per year (if run for 6 months).
Solar attic fans, on the other hand, cost an average of $600 and require no professional electrician—they can often be installed by homeowners themselves in under an hour. Like all solar energy products, you can also receive the 30% Residential Renewable Energy Tax Credit, which would decrease the upfront cost to $420. Once the solar attic fan is installed, it uses absolutely no energy and is free to operate. This puts the upfront costs practically even, you will not pay for additional electricity to run the fan, and your overall electricity usage to cool your home should be reduced—making this a financial win.
There are several companies offering solar attic fans on the market today. Below, we look at three of the most prominent companies offering the highest quality and most durable products, at competitive prices.
Remington Solar offers 20, 25, and 30-watt solar attic fans. Unlike other products, these solar fans are priced on par with electric attic fans. For example, the 30-watt solar attic fan has the ability to actively cool over 2,200 square feet of attic space and only costs $449. A similarly sized, high-performance electric attic fan would cost the same if not more after factoring in the cost of hiring an electrician. All of Remington Solar´s attic fans also work well for homes that have one or several ridge vents.
Natural Light is another company marketing a high-performance solar attic fan, with user-friendly setup requirements for a weekend morning DIY project. When properly utilized, this solar fan will help reduce the load on your HVAC system while also extending the lifespan of your roof. For homes located in shaded areas, the solar panel on this attic fan can tilt up to 45 degrees in order to maximize the amount of sunlight captured. This 24-watt solar attic fan costs just over $400 dollars, making it an affordable way to improve the thermal performance and energy efficiency of your home.
Amtrak Solar is another company specializing in a wide range of solar attic fans. If you live in southern Florida or Arizona, their 70-watt solar attic fan is one of the most powerful products on the market and packs a lot of punch when it comes to sucking out the hot, muggy air that accumulates in your attic. At under $200 dollars, this is one of the best deals you can find for quality attic fans. Despite the fan and blades being rather small compared to other fans, the extra power allows the smaller fan to circulate enough air to do the job.
If you want to protect the new roof that you just installed on your home or simply want to keep your attic space comfortably cooler to lower the load on your air conditioning system, any of these solar attic fans are great investments that will improve the overall energy efficiency and comfort of your home, without driving up your utility bills.
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.