What is a solar attic fan and how does it work?
A solar attic fan is simply a mechanical fan, similar to those you likely have elsewhere in your house, that is installed in your attic and powered by solar panels on the roof. Most attic fans don’t even need to be connected to your home’s electrical circuitry for backup power since you only need the cooling effect of the fan on hot, sunny days when the solar panels are working at maximum capacity.
These fans might seem like a small addition to your home, but they can provide a significant cost savings on your electric bill by reducing the amount you need to run your air conditioner. By circulating hot air in the attic, these fans are able to remove heat from one of the places it tends to pool inside your house and pull in fresh, cooler air. The result is that your attic won’t overheat, keeping the rooms below from heating up in turn and extending the life of your shingle roof by preventing the shingles from heating from below.
One thing to note about solar attic fans is that they can be somewhat expensive to purchase and install – which means that you’ll need to get at least several years of use out of the fan to recoup your initial investment.
However, unlike traditional powered attic fans, solar fans do not cost anything to run once they’re installed. They also don’t draw nearly as much power as traditional fans, so there are no concerns about generating negative air pressure that can pull conditioned air or unwanted gases like carbon monoxide from your oven into the attic.
Features to consider while choosing a solar attic fan
How do you know which solar attic fan is right for you? In this section, we’ll cover the most important features that differentiate solar attic fans to help you choose the fan you need.
Does power matter?
Since solar attic fans don’t cost anything to power, the amount of power that they draw only affects the size of the solar panels that will be needed on your roof. If you have a roof that does not have much sun exposure or much space to install solar panels, then power can matter quite a bit – your panels will need to capture enough sun to consistently meet the power requirements of your fan. However, for roofs that have plenty of direct sunlight, the power of your fan is likely not an important consideration when choosing a fan.
How much space do you need to be ventilated?
If power is not a concern, you can base your decision of which solar attic fan to buy based largely on the square footage of your attic. A larger fan will be able to circulate more air, which is important if you have a large attic with lots of hot air that needs to be recirculated. Typically, attic fans’ abilities to move air is measured as airflow capacity in cubic feet per minute (CFM), and a 1,000 CFM fan should be able to provide enough air flow to circulate air over a 1,600-square foot or greater square foot attic. Thus, a 1,000 CFM fan is considered to have a coverage area of 1,600 square feet, while the 1,750 CFM fan from GBGS will have a coverage area of up to 2,800 square feet.
Consider size and weight
A bigger fan, with a larger coverage area, will almost always be larger and heavier, although this also depends on the design materials – for example, the small 1,280 CFM fan from Brightwatts weighs 28 pounds compared to the 34.5-pound 1,750 CFM fan from GBGS. Size can be important if you have limited space in your attic or a small entryway, since you need to be able to get the unassembled fan into the attic and have the blades rotate without obstructions.
Weight is a consideration for where exactly you can install the fan, since a heavier fan will require more support from your roof.
It will take more than a few years’ worth of use to recoup the initial investment into your solar attic fan with savings on your electric bill from using less air conditioning. Therefore, it is essential that your fan will last for many years to come. You can ensure that this will be the case by choosing a fan with a long warranty – for example, both Natural Light fans come with 25-year warranties. Remember to ensure also that the warranty covers both the fan motor and the solar panels, since either of these components can be expensive to replace.
How to install a solar attic fan?
Although many people opt for professional installation of their new solar attic fan, you can save money by tackling this project yourself. You will need to first install the roof brackets and fall-arrest system for the solar panels to the desired location on the roof. Then you will need to use a reciprocating saw to cut the shingles on the roof to the shape of the circular base of the fan, and mount the fan to the roofing brackets. You can secure this with caulk and then use a roofing nail to replace shingles in the area immediately around the brackets.