Taking a Shine to Precast

By Bridget McCrea

The U.S. solar market is in the middle of a growth spurt, and it’s pulling the precast concrete industry right along with it. According to the Solar Energy Industries Association, the market is expected to grow by 119% this year. Installations are set to reach 16 gigawatts – more than double the record-breaking 7.3 GW installed in 2015 (1).

Much of that growth will be driven by utility-scale installations, with residential and commercial projects also on track for strong growth in 2016. During the first quarter of this year alone, 1,665 megawatts of solar photovoltaic projects were installed in the U.S., with the solar industry adding more capacity than the coal, natural gas and nuclear industries combined.

SEIA reports there’s an “enormous amount of capacity in the pipeline,” with more than 53.3 GW of photovoltaic and concentrated solar power projects either under construction or under development.

Precast concrete has already made a name for itself on a few large solar projects in the U.S., so if past history is any indication, owners may look to incorporate more of it moving forward. And, if the precasters involved with these projects have their way, that trend will persist as the solar market continues to expand in 2016 and beyond.

The only option

As momentum in the U.S. solar market continues to build – and as more engineers and specifiers explore the value that precast offers for these initiatives – expect to see more precasters getting involved with eco-friendly energy projects.

“When you start to talk to specifiers and engineers about precast’s strengths, including the speed of manufacture and installation, quality of product and the fact that projects can be completed in the dead of winter,” said Aaron Ausen, vice president at Dalmaray Concrete Products in Janesville, Wis., “they really take a shine to it.”

Ausen said Dalmaray secured its first major solar endeavor after reading about a solar field project in Beloit, Wis., last year. Thanks to a good working relationship with Alliant Energy, the local utility company, he connected with the engineering team to learn more. The team had not considered precast, and the project was grappling with an unresolved issue and had been temporarily “mothballed” due to that hurdle.

“When the project fired back up again, Alliant Energy knew what it wanted to do but didn’t really know how to get there,” said Ausen, who noted that the utility company had previously used precast on a single, small-scale project. That project was successful, but wasn’t of the same scale or magnitude as the new project. To get precast’s selling points across to the customer, Ausen developed a two-page document outlining why precast was a better solution than cast-in-place concrete.

“That really opened their eyes to the benefits of precast and pushed them to dive a little further into it,” he said.

For the Rock River Solar Project, Alliant Energy planned to install solar tracker pads on top of a capped landfill in Wisconsin. The utility company and its partner, Korean solar energy firm Hanwha Q CELLS USA, had to meticulously engineer the structures that hold the solar arrays, because state law does not allow landfill soil to be disturbed.

Because the landfill contains a liner buried two feet below grade, the typical solution of driving I-beams into the ground was not possible. In addition, the project called for a winter installation. Dalmaray’s custom precast solution minimized concerns and offered benefits no other alternative could provide.

“Precast was the only option at this time of year,” said Mark Miller, senior manager-estimating and pre-construction services for civil contractor Michels Corp. “Having the ballast blocks cast in a temperature-controlled environment and shipped to the site enabled the work to be completed in the winter.”

Speed and flexibility

Dalmaray’s flexibility was paramount to the success of the project. Each time Alliant Energy changed its plans – be it the connections, bolts or any another component – the precaster reacted quickly, altering the design without adding time or complexities to the project.

“Through that process, the customer came to understand the full gamut of precast’s benefits and just how agile and flexible it can be on a major project like this,” Ausen said.

For example, project engineers originally specified I-beams that supported the concrete panels. The beams were to be cast on site, but when Ausen learned that those pieces had to be installed within one degree of tolerance – on ground that wasn’t perfectly level – he came up with a better alternative.

“We embedded the I-beam with a floating, 1-inch steel plate mounted on anchor bolts,” he said. “This allowed the plumbness to be adjusted and for that very tight tolerance to be achieved.”

In addition to the 1,659 precast footings, Dalmaray manufactured many smaller precast items at the customer’s request.

“We kind of wound up turning into the Walmart of precast,” Ausen said. “With everyone coming to us asking us to produce different pieces for them, our answer was always, ‘Sure, we can do that. No problem.’”

Looking back, Ausen calls the Rock River Solar Project the “biggest and best” the company has ever done and added that Dalmaray is looking forward to working on more solar initiatives in the future.

“It was definitely a turning point for our company,” he said. “In fact, we just got a call yesterday about a new solar project in Illinois. They want us to come and look at the design and lend our expertise to the project.”

Putting precast on the map 

Elsewhere in the Midwest, Lindsay Precast of Canal Fulton, Ohio, sprang into action and developed a custom solution to help a customer who needed a concrete pad developed for its solar power inverter stations in Maryland.

“They were looking at different options and came to us for help,” said Lynn Grimm, specialty projects manager. “We enjoy custom work, so we brainstormed with their engineers to come up with a workable design for the project.”

For the pads, the customer sought a solution that would be more durable and cost-effective than steel. They were also looking for a material that would eliminate the need for cast-in-place foundations on some sites. The answer was precast concrete.

The project required custom design work and precise engineering due to the complexity of the equipment it supports. Features cast into the solar skids included conduit for 120/240 volt and data connections, a 4/0 copper ground loop with stainless steel landing plates for field grounding connections and stainless weld plates. The weld plates anchor the control station and the power panel components as well as a site-installed canopy. The slab also has cast-in cable tray grooves for running the large AC power cables with inserts for attaching and sealing the aluminum cable tray covers.

“Each solar skid includes custom components, and we were able to adjust as the project progressed because we have our own on-site fabrication division,” Grimm said. “It was all tailored to the job by specifics, and depending on what each solar skid included.”

In the field, the pads help facilitate a complex process that converts the sun’s rays into usable energy for the power grid. Wires combine the DC electricity from the solar panels and send to the hardware fixed to the precast pad, where it is converted it to AC electricity. The AC electricity runs through nine, 1 1/4-inch diameter cables connected to the low voltage side of the transformer using the grooves in the pad. Lastly, the medium voltage side of the transformer transfers the electricity to the grid for use.

According to Grimm, the solar power inverter station project was successful and the company is already working on several new solar initiatives.

“Like many other industries looking to achieve high levels of quality and cut down the on-site installation time, the solar industry is definitely headed in the direction of using prefabricated materials,” she said. “We’re still working to get the word out to designers and customers about this, as many of them don’t even know about the grand possibilities of precast. Going forward, we’ll continue working to get our industry on the map in solar construction.”

A bright future

As the amount of solar work in the U.S. continues to rise, project owners are in ever-increasing need of a high-quality building material that meets the multi-faceted needs of the industry. Precast concrete producers stand ready to provide solutions that are durable, easy to install and customizable for nearly any situation.

Bridget McCrea is a freelance writer who covers manufacturing, industry and technology. She is a winner of the Florida Magazine Association’s Gold Award for best trade-technical feature statewide.

Endnotes

(1) seia.org/news/us-solar-market-set-grow-119-2016-installations-reach-16-gw