Residential solar projects tend to be built on rooftops by default, as homeowners always have a roof but might not have yard space for an array. When there is enough space outside of the home for solar, there are advantages for installation and upkeep of the PV array, and, in some cases, it makes more economic sense.
Credit: Advancing Solar Solutions
Taylor Mills runs Advancing Solar Solutions, a PV contractor based in Ripley, West Virginia, and is that rare residential installer doing more work on the ground than the roof. He estimates that 65% of his business comes from ground-mounted solar projects, and part of that is owed to working in rural areas in West Virginia, Pennsylvania and Ohio where there is often ample land for this type of construction.
“I will never have someone call me and say, ‘Hey, my roof’s leaking, and I think it’s because of the solar panels you put on.’ I’ll never have to field that phone call with a ground-mount,” Mills said.
While this isn’t typically the case, Advancing Solar Solutions installs ground-mounted solar arrays that cost less than rooftop projects. Mills shared an example quote for a solar project that pitched both a rooftop and ground array for a single client where the latter was more than $3,000 cheaper. The cost difference mostly comes from Mills’ preference to use Enphase microinverters on rooftop projects to meet rapid shutdown requirements and offer clients module-level monitoring. However, some cost-saving benefits extend beyond component choices.
Roof space can be limited compared to a yard. Where a rooftop array might cover most of a home’s energy need, depending on the space available, a ground-mount array can be sized to produce more than 100% of it, feeding more electricity to the grid with solar, yielding higher net-metering compensation and a shorter payback period on the system.
Hilary Fiene, chief office manager at Stateline Solar, said residential ground-mount and rooftop arrays have comparative prices. Stateline Solar serves clients in both rural communities and towns, and about half of the company’s residential solar output is ground-mounted.
“The country folks have the opportunity to do roof vs. ground, whereas the people who live in town typically have to do a roof-mount,” Fiene said. “Most of the towns’ permitting processes just don’t allow for ground-mounts. But since we have a huge number of people that live in the country in our area, it gives us a lot more opportunity to do the ground-mounts.”
Compared to a rooftop project, the racking structure for ground-mounts costs more. These systems use steel supports that need to be pile-driven into the ground, attached to concrete footers or held in place by non-penetrating, heavy ballast blocks. Then steel racking is attached to these supports to hold the solar modules. This process requires specialized heavy equipment, unlike the hand tools necessary for mounting on rooftops.
“However, we consider that we keep our workers safer because they don’t have the risk,” Mills said. “Yeah, they can fall in a trench, but they can’t fall off a roof.”
Credit: Advancing Solar Solutions
Working on the ground, installers don’t need to worry about voiding a roof warranty, but should consider what’s beneath the soil — rock, electrical or plumbing lines.
Post-installation, ground-mounts provide simpler access to certain components than rooftop arrays. Where a service technician on a rooftop job will have to detach and lift modules to get beneath the array, accessing under-panel components on ground mounts is just a matter of getting under the array. At a company-level, that translates to fewer truck rolls and less time spent on an array for maintenance, Mills said.
“A lot of our work actually is uninstalling and reinstalling solar systems so that roofing can be done, and with a ground-mount, you never have to worry about that,” he said. “We’ll often charge someone between $5,000 to $7,000 to remove a system and then reinstall it, in addition to them getting a new roof.”
Homeowners can also be more engaged with ground-mounted projects without climbing onto their roof. Although they may need to landscape around the project, they can also easily clean dirty panels at the ground-level. Certain types of ground solar racking, like pole mounts, can be manually adjusted for better energy yields as the sun’s path changes throughout the year.
Ground-mounted solar won’t work for every homeowner. Sometimes the roof is the only option. But if there’s room for some modules on the ground, it can be built outside the pitch and perimeter of a roof line and still meet a home’s energy needs.
“Each company is different, they cater to a different audience, but I think it’s important to allow the customer to be fully educated — if they have the option to do roof or ground for their home, if they’re not limited by a city or village permitting requirements,” Fiene said. “I see a lot of people that we service get pigeonholed into going one route when they find out they had an alternate route they could have gone, and it’s a lot of buyer’s remorse, so I think it’s nice for them to know their options.”
