Solar Powered Fans for Greenhouses, Sheds, Coops and Camping

A solar powered fan runs from its own small panel, so it can vent a greenhouse, shed or chicken coop with no outlet nearby. Size a greenhouse fan to change the air once to one and a half times a minute, pick a kit with a battery if it must run in cloud, and keep coop fans off the birds.

Battery or no battery: how solar fan kits differ

A solar fan kit pairs a small panel with a low-voltage DC fan. The big difference between kits is whether a battery sits between the two.

A fan wired straight to its panel has one built-in advantage: it spins hardest when the sun is strongest, which is when a closed greenhouse or shed heats up fastest. A battery adds cost but lets the fan keep working after the light fades. Either way, the panel needs open sky, so choose a kit with a long enough cord to put the panel in the sun and the fan where the air needs to move.

What size solar fan does a greenhouse need?

University of Georgia Extension says exhaust fans have replaced flow-through ventilation as the main way to cool hobby greenhouses, and that a fan should be large enough to change the air in the greenhouse one to one and a half times every minute. Fans are rated in cubic feet per minute (CFM), so the math is simple: length times width times average height gives the volume in cubic feet, and that number is the CFM to aim for, up to 1.5 times more.

Compare the CFM on each listing with your number. If one solar fan falls short, a second fan or an open vent or door can make up the gap.

UGA Extension also notes that a thermostat can switch ventilation on automatically as the air warms, and puts the maximum greenhouse temperature in most situations at 85 °F. A direct-drive solar fan has no thermostat of its own, so on a cool, bright day it runs whether the plants need it or not.

Ventilating a chicken coop with a solar fan

Coop ventilation is about air quality as much as heat. Oregon State University Extension says ventilation removes ammonia fumes, carbon dioxide and moisture and brings in fresh air, and that a well-designed coop has enough air exchange without drafts.

The same guide says passive ventilation, through windows and through vents in the gables, eaves or roof, is adequate for most backyard coops. Fans are for especially warm or humid periods, placed so they do not blow air directly on the birds.

Power is the other reason solar appeals for a coop. A Mississippi State University Extension veterinarian warns that fans must be used safely, because electrical barn fires are not uncommon. A solar kit needs no extension cord run out across the yard, though its wiring still needs to be kept away from pecking beaks and nesting material.

Solar fans for sheds and workshops

A shed with no power line is the simplest case: mount the fan in a wall or window opening, run the cord to a panel in the sun, and let it pull hot air out on sunny days. Cover the opening with mesh or a louvered grille so it does not let in rain or animals.

To run lights or tools in the shed as well, a separate panel and battery makes more sense than a fan kit. Our guide to small solar panels covers what a 10 to 100 watt panel can charge. Solar panels for sheds compares the full options. For a hot attic, see solar attic fans.

Solar fans for camping and outages

For a tent or a porch, a rechargeable fan is the usual choice. Charge it from a small solar panel or a portable power station during the day and use it at night. Our guide to what a 1000Wh power station can run shows how to work out run time from a device’s watts.

Before you buy a solar fan

1. Measure the space and work out the CFM you need.
2. Decide whether the fan must run after sunset or in cloud. If so, choose a kit with a battery.
3. Check the cord length between panel and fan.
4. For a coop, plan where the fan sits so it moves air without blowing on the birds.

More solar gear for outside, from lights to lanterns, is in our outdoor solar section. Solar pumps and fountains are in the pool and water section.