No room for solar on a high-rise? Seek out a parking deck

Locating open surfaces that can host solar arrays large enough to offset a substantial amount of energy can be a challenge in cities. Often, rooftops are riddled with obstructions like HVAC units, and there isn’t enough roof surface on high-rises to build a solar system that could offset significant electricity use — not to mention the added challenge of lifting equipment to that height.

Instead of subscribing to solar systems built outside the city for energy credits, solar EPC SunGreen Systems of Pasadena, California, has found some luck with urban installs by putting long-span solar carports atop multi-level parking decks.

“It’s very difficult to offset a high-rise building because you don’t have that rooftop to square footage floor area that you normally do with a warehouse or manufacturing facilities,” said Alex Deeter, sales and marketing engineer, SunGreen Systems. “It’s rare that you get these large open areas with parking garages in order to offset that load and actually be able to use the renewable energy option.”

In several cases, SunGreen was able to offset a major part of their clients’ electricity loads with carport solar systems on the buildings’ accompanying parking decks. The company’s latest parking deck system was completed in August 2019 — a 1-MW solar array covering the top level of an attached parking deck at The Atrium office building in Irvine. It is currently the largest long-span solar carport in Southern California.

The Atrium

Real estate developer The Kelemen Company was in talks with another contractor in 2018 to install a solar system at its recently acquired office building, The Atrium. After seeing SunGreen’s last long-span parking garage install at the Morgan Stanley building in Irvine, Kelemen contacted the solar EPC and switched over.

“We ended up going with SunGreen because we knew that they’ve already done this and that made us comfortable about it,” said Tibor Kelemen, founder and CEO of The Kelemen Company. “SunGreen turned out to be a great company because not only did they perform according to the budget that they quoted us early on, but [they] also stuck with the schedule. To us, on-budget and on-time is like 75% of the equation.”

The Atrium’s elevators, hallway lighting and HVAC electrical needs are now covered by solar. The property hosts a 330,000-sq.-ft building comprised of two high-rise towers, with covered walkways connecting the structures, and an attached five-level parking garage, where the solar carport now resides. The building includes coworking spaces, a security firm, a five-star restaurant and more.

The roof space of The Atrium office building is occupied by a helipad, and, if built out with solar, could have only handled a third of the capacity the attached parking garage offered.

“To have a 1-MW project, I think that this was the only coverage area. So, we saw this as a win-win. The carport is shorter than the building, so in terms of height we knew that this wouldn’t have prohibited us from doing it,” Kelemen said.

There were concerns that adding any height to an existing structure would cause issues with the Federal Aviation Administration relating to the nearby John Wayne Airport. But getting approval from Irvine’s electrical and fire code inspectors turned out to be the bigger hurdle.

Construction and permitting

The solar system was included in the building’s total financing when The Kelemen Company purchased the property in 2018. Engineering on the array started a few months later and construction followed shortly after in early 2019, with the project completed in August of that year.

The solar canopy is comprised of United Renewable Energy 375-W modules, Yaskawa Solectria Solar PVI 60TL string inverters and a full-coverage solar parking garage structure fabricated by Skyline Steel of Arizona.

Installers had to core through the concrete structure of the parking deck in order to mount the canopy supports and run wiring from the top level of the five-story structure to the combiner box on the ground level.

Each canopy support footing was a baseplate secured with several bolts that required a matching cored space in the concrete, with the added challenge of avoiding contact with any structural supports during coring. SunGreen had to secure a conditional use permit (CUP) to install the system, ensuring the canopy would not come within 2 ft of a parked vehicle, parking curb or any structural column.

“It was really challenging to do in a situation like this,” said John Hoffman, CEO of SunGreen Systems. “That’s the main thing the CUP wanted us to demonstrate — that we weren’t going to modify or lose any parking.”

A lot of the construction and wiring had to be handled after business hours and into the night to avoid disrupting business or parking for the tenants. Four weeks of coring resulted in a piping network that guided wiring from the top deck, down five levels, across the driveway and into the building; and then another 200 ft of wiring was sent in two directions to connect and distribute the power throughout the building. The city inspector required the array’s wiring to be kept inside the parking deck.

Unlike a commercial rooftop project, where panels would be set at a 5 to 10° angle, panels were installed at a 2° slope on the parking deck canopy.

“It has slightly less production, but it’s using a space that wasn’t utilized before,” Deeter said.

He added that assembling panels was a much quicker process than coring and erecting the steel columns of the canopy.

Panels were laid with 2-in. gaps between them, and there are 12 empty slots among the 2,688 panels to allow proper ventilation in the event of a fire. That way, SunGreen subcontractors didn’t have to also install a sprinkler system.

“A lot of these buildings, especially these mid-rise, high-rise buildings, if they want to meet their environmental goals, then they have to think outside of the box. You have to find space where you’re not typically looking,” Hoffman said. “That’s what these structures are able to do: cover large areas, create a lot of power to offset the kind of demand that you have in a building like this and also improve tenant experience of being able to park in the shade, plug into an EV charger and have it well-lit with LED lights from corner to corner.”

Post-construction

The top level of The Atrium’s attached parking deck wasn’t a popular option for tenants prior to adding a solar canopy. Now, guests can park comfortably, without direct exposure to the hot California sun.

“We all have to take some responsibility in curbing our carbon footprint,” said Tibor Kelemen, CEO and founder of The Kelemen Company. “I think that to the extent my voice carries to other potential building owners, operators, I say that if you don’t already understand the benefits of this, to those folks, they ought to go out and look at it, because I think collectively, we can make an impact on our planet and the next generations to come after us.”