In another first for Mill 19 at Hazelwood Green, crews have placed the final solar panels on the largest single sloped solar array in the country — 4,784 silicon panels that will power the entire facility.

The $5 million project is the largest solar installation in Pittsburgh and, unlike typical spot installations on flat roofs, the largest on a sloped surface in the U.S., says Mike Carnahan, vice president and general manager of Scalo Solar Solutions, a division of Burns Scalo in Thornburg.

His crews will spend the next few weeks connecting the installation to the grid and hope to flip the switch to make it operational by the end of July. It’s an apropos way to mark the company’s 10th anniversary, says Carnahan.

“My guys are about to take a champagne bottle and break it off the side of the building,” he says.

Scalo will own the solar installation and claim the one-time, 30 percent federal tax credit on its installation cost. RIDC, which built Mill 19, will buy energy from it — paying Scalo Solar an estimated $12,000 monthly to provide electricity for all the tenants, says Carnahan.

“Their Duquesne Light bills will be next to nothing,” he says. “As far as the energy being generated, we’re going to be providing the vast majority of that.”

With solar panels tied to the grid instead of batteries, any energy produced and not used goes through the electric meter back to the utility company, which credits the consumer dollar for dollar.

“Basically, you’re using the grid as storage,” says Carnahan. “Your meter on your house will spin backwards if you’re not there to use the electricity.”

In 2015, Scalo Solar began working with RIDC and Almono, the group of foundations that conceived of the Hazelwood Green development, to enable Mill 19 and other parts of the 178-acre site to be entirely sustainable. The power purchase agreement was a way to make the project affordable by utilizing tax credits that the nonprofit organizations would not be able to take advantage of.

“We’ll provide 100 percent of the annual net power required for the buildings here in Mill 19,” Carnahan says. “We might underproduce in winter, because of snow and lack of sunlight, but we’ll overproduce in summertime to be net zero. … Nighttime, they’ll be using the grid; daytime, they’ll use solar.”

Here’s how it works: The panels are made of solar-grade silicon that sits under glass. When sun hits the panels, electrons bounce around and knock other electrons loose, then wires collect the power and feed it down to building.

“As long as the sun’s out, even in the mornings with early sun, we can produce power. It’s based on light — they’re photons,” Carnahan says. “In the middle of the day, a nice sunny day, we’re producing lots and lots of energy.”

The 90,000-square-foot Mill 19 sits within the frame of the former Jones & Laughlin Steel Company mill. Carnegie Mellon University’s Advanced Robotics for Manufacturing (ARM) and Manufacturing Futures Initiative occupy the first two floors. Catalyst Connection is on the third floor, and O’Hara-based self-driving car company Aptiv is another tenant.

Scalo Solar’s crews are also installing panels to power Hazelwood Green’s parking lots, pedestrian plaza, parklet and water features. The panels will be installed atop custom canopies by September. Since the parking lots’ lights and gates won’t use much power, some of the energy will power the fountains in the park.

“The idea is to have 10 times more solar down here eventually — every building, every parking lot, so that everybody will be using renewable energy,” Carnahan says.

Scalo Solar has done other big projects in the Pittsburgh region and Ohio, including Giant Eagle Market District and GetGo stores, Chatham University’s Eden Hall campus, Carnegie Science Center’s new addition, and a microgrid project at Phipps Conservatory’s exhibit staging center. The company is currently installing 700 some panels on a Lane Steel building in McKees Rocks.

“We see the industry just growing and growing. It’s not going away — it’s the fastest-growing industry in energy,” says Carnahan.