Chances are that when you picture solar panels in your mind, you picture gleaming rectangles on a home's roof. Direct roof mounting is the most common way of installing photovoltaic (PV) panels, but what happens when your home has gables too steep, dormers breaking up the surface, too much shade on the house, or other rooftop complications? Those homes do not have to be left out of renewable energy production. Panels can be mounted off the house instead.
Pros and Cons of Ground Mounting
If the complicated roof style described above is what you're working with, then the most obvious pro of ground mounting is that it doesn't involve the roof. A framework could be erected in the dog run on the south side of a home, for instance, elevated sufficiently so Rover can still run. Perhaps your home's roof needs repairs that you'd rather not deal with right now. Such repairs should be made before any rooftop system gets installed. So if your roof has caused you to rule out going solar, our advice is to think outside the box; think off the roof.
Square footage is probably more abundant around a home than on its complicated roof. According to estimates drawn up by the U.S. Department of Energy, 200 square feet of solar panels working at a typical 12% efficiency are needed to produce 2,000 kilowatts of power. If you wish to produce energy up to the cap set by the net metering laws in most states, 10,000 kW, you would need 1,000 square feet of panels working at 12% efficiency. Three spots in an average parking lot equal about 1,000 square feet (PDF source, A Consumer's Guide: Get Your Power From the Sun).
Three spots in an average parking lot equal about 1,000 square feet.
Another benefit of ground solar arrays is that they can swivel and turn to track the sun throughout the day. Mounted where they see both sunrise and sunset, the panels can reposition all day automatically for maximum efficiency. Even if you don't opt for a moving array, ground mounting lets you fix the panels to face directly south, where your roof might not face.
A fourth pro of ground mounting is easier maintenance. Roofs are up high, and roofs can leak.
The cons of a ground system come down to cost and looks. Compared to a typical rooftop system, a ground framework is more expensive. Rigid frames and concrete posts are required. Stability in high wind is a concern here, but not with direct-mounted rooftop arrays. You don't want your panels flying away like Aladdin's carpet.
Ground systems look industrial. Ugly is in the eye of the beholder, but everyone can agree that a big shiny array will be impossible to miss around your property. But there is a compromise, a way to mount solar panels off the ground and off the roof, that looks smart and cool.
Great Compromise: Not on the Ground, Not on the Roof
So your roof isn't suitable for a solar panel system, yet you don't want a blight on your outdoor views from an industrial-looking array. Isn't there a middle ground? Yes!
Check out photos 18 and 19 of the Coyote House gallery as written up by the Los Angeles Times. The homeowners in Montecito, California, mounted their solar array as a pergola, casting dappled shade onto a terrace. The array is large enough to supply nearly all of the home's electricity and works as an architectural feature of the home, doing the job that a wooden pergola might have done.
The home's two roofs are green roofs; that is, growing space for plants (photos 1 and 17). Said the homeowner Van Atta, who is a landscape architect, "Instead of looking out across a hot roof, we have a lovely green area to entertain friends."
Beautiful and useful green roofs and a shade-casting solar panel pergola that generates almost all the electricity the home needs—a great compromise!
“Instead of looking out across a hot roof, we have a lovely green area to entertain friends.”
- You don't need a wide flat roof to produce solar power at home.
- While more expensive than roof mounting, ground mounting offers the advantages of positioning, sizing, and easier maintenance.
- A solar array can serve double duty as a pergola or carport. The choice goes beyond roof vs. ground.