Want to add renewable energy but don’t have a roof that can support a solar array? Don’t abandon the possibility of solar energy if your roof isn’t an option. Look to unused areas of your property instead.
Solar panels can be placed on parking canopies or ground- and pole-mount units. These additional configurations can achieve the same output or greater as a rooftop installation.
The Limitations of Roof Arrays
There’s no shortage of reasons why a building owner would pursue renewable energy – lowering your electricity bill, earning a point toward a green building certification, slashing your carbon footprint, or making a public statement about your environmental commitment are powerful incentives for any facility.
Among the renewable energy options available to facility managers, solar is perhaps the most comfortable and trusted. Its years on the market make it a proven technology with consistent performance and a quantifiable payback and ROI. Though rooftop solar arrays are a common option, they aren’t always the best fit for a commercial building.
Some roofs serve as an architectural element and the addition of solar panels would be at odds with the building’s design. Others are unable to support the added weight of solar racks and even if they could, the roof itself may not offer enough square footage to effectively produce energy.
“Roof mounts tend to be limited in size. Module spacing is determined by the roof size, so system performance might be restricted because of physical limitations,” says Joe Thomas, CEO and president of MAGE SOLAR, a solar provider. “The orientation and pitch of a roof will also determine what a system can ultimately yield because architectural and physical boundaries come into play.”
For other facilities, it’s not the right timing to add solar panels. Because the average life of a commercial roof and PV panels is 25 years, it’s best to add solar panels immediately after a roof replacement. But if you are in the middle of your roof life, you may not want to wait 10-15 years to secure solar energy.
Visibility and accessibility are also sacrificed with a rooftop array. Most arrays are hidden from public view, making it difficult to display a commitment to sustainability. And with PV panels tucked away on the roof, installation and maintenance can be a hassle.
Capture Sunshine from the Ground Up
In lieu of a rooftop array, you can add PV panels to poles or ground racks. Each option uses the same panels as a roof array – the only difference is the racking system. However, these alternative options allow you to leverage panel orientation to increase output.
Ground-mount systems are suited to properties with available land, such as campuses or public and corporate buildings with sizeable grounds. They can be installed in a variety of soil conditions and proper placement won’t interfere with existing landscape designs.
Unlike a roof array, you can adjust the panel angles on ground-mount arrays to better absorb sunlight.
“Ground-mount systems can be tilted at an optimal angle, which varies depending on how far south or north you are,” explains Mike Grunow, marketing director for manufacturer Trina Solar. “An angle suitable in Texas is different than one in Minnesota because of their proximity to the equator. When you have a roof array, the angles are limited because you have to consider how much wind the panels could catch.”
Ground-mount solar is also relatively simple and fast to install, requiring only light trenching to secure the racking system and a small crew to fasten the panels.
“Due to the ease of accessibility, maintenance on ground mounts is easy, fast, and cost-effective. Modules do not have to be removed and temporarily stored in case the roof needs repair or maintenance,” Thomas explains. “Systems can be visually checked, washed off, and worked on without the same safety measures you need on top of a three-story building.”
Because ground arrays are the most accessible, however, owners should note that they may need additional security measures in place. They are vulnerable to vandalism, theft attempts, damage from cars (if near a parking lot), and even rocks from lawn mowers.
Despite these considerations, ground-mount arrays offer an attractive payback option. “The economics of ground-mount solar systems, from the upfront capital costs to the straight-line payback and ROI, are typically the best,” says Grunow. “They install the quickest with the lowest capital costs and the least amount of labor.”
Harness Energy at New Heights
If land space is inadequate, consider a pole-mount array. PV panels are attached to sturdy poles several feet off the ground, similar to a satellite dish.
Pole-mount options are compatible with northern climates that are subject to blizzards. Some provide the ability to store the panels in a vertical position, reducing snow and ice build-up.
Panels are also equipped with a tracking platform that allows them to slowly pivot so they have near-constant sun exposure throughout the day.
This configuration is more expensive to install because of the added materials required for the pole construction and the tracking system. However, these costs are easily countered because this type of array can produce an average of 25% more energy than its counterparts.
Generate Power in Parking Areas
If you have a sizeable parking lot, you can add dual functionality by installing solar canopies. Because parking lots can offer the same square footage as a rooftop, they are an ideal area to produce solar power.
“Parking canopies have become rather popular because they generate electricity while providing shade and shelter in previously unused spaces,” says Thomas.
A solar canopy offers the coverage of a ground-mount array with the installation properties of a pole-mount system. The canopy is supported by reinforced columns that are specifically designed to support the size of the array.
As a continuous structure, panels can be arranged as a single slope or in a Y configuration. You can also elect to create “trees” or individual canopies throughout a lot (see page 39), depending on your preference and budget.
Both array designs provide shade, creating a premium parking spot. You can further green the canopy by pairing it with an EV charger. Stations for electric vehicles are an attractive way to increase business traffic and boost your sustainable profile. With solar panels providing off-grid power, you can offer net-zero energy to EV owners.
If you already have a rooftop array, solar canopies can stretch the performance of existing panels to boost your total output. Canopies also increase the visibility of your renewable energy initiatives, particularly if your roof array is hidden from view. From an aesthetic perspective, canopies add an architectural element that can beautify an otherwise monolithic parking lot.
However, note that parking canopies require added installation costs. Canopy supports must be custom-built for your parking lot and solar array specifications. Seismic reinforcement may also be required depending on your location. These additional costs may represent an overall increase of 10-15% of the array’s upfront investment.
To alleviate any security concerns, consider the safest location for the array on your property. Some owners may use the building as a visual shield by placing a ground array behind it while others elect to place a fence around the panels. Pole and canopy panels are typically too high for vandalism.
Regardless of array type, most PV panels come with security screws that require a special tool, Grunow adds, eliminating the chance that someone could casually steal part of your system. If theft or vandalism is still a concern, you can aim a security camera at the array.
Whether you select a pole, ground, or canopy array, these alternative mounting systems offer expanded possibilities for renewable energy
Jennie Morton (firstname.lastname@example.org) is
associate editor of BUILDINGS.