MENOMONEE FALLS, Wis. (December 10, 2020) – When Marc Maguire, assistant professor of construction programs at the University of Nebraska-Lincoln, started testing the strength of piles made by Nucor and used in the support assemblies of solar panels, he didn’t expect such surprising results. These tests ― conducted by the Durham School of Architectural Engineering and Construction ― examine the performance and deflection of the pile materials for the design loads. The loading resembles environmental pressures such as wind and earthquakes that can cause significant damage to solar panels over time if not designed properly.

The results of this test can be highly impactful to the solar industry because it is predicted that solar installations will surge over the next few decades as more sustainable infrastructure plans are put into place, and, unfortunately, many steels and corrosion protection measures used for solar panel piles are expensive and harmful to the environment. But, although the study is ongoing, Maguire and his team of graduate and undergraduate students have tested a new material that defies the strength, cost and sustainability of the typical steel used for solar piles.

The Durham School of Architectural Engineering and Construction tested the strength of solar panel piles made by Nucor. Left to right | Back row: Russ Snygg (Enerpac Territory Manager), Matt Henggeler, Marc Maguire, Jacob Luebke, Salam Al-Rubaye, Jose Lopez, Zach Benson, Front row: Nathaniel Colton, Fray Pozo-Lora

“Nucor ― North America’s most diversified steel and steel products company ― approached the university to test a new Ultra High Strength Weathered steel material, made with a revolutionary process called Castrip®. This material is fabricated as a sheet and then cold formed into shapes specifically for solar industry applications, which is approximately “8in x 5in and 1/16 of an inch thick,” said Maguire. “Castrip wouldn’t have traditionally been considered for this application because of its flat shape and light weight. However, it was discovered that by bending it into complex geometric shapes, it gains a lot of strength. And this strength is just one of many benefits Castrip offers.”

Nucor’s new Ultra High Strength Weathered steel material used as solar panel piles

Most steels that are traditionally used to manufacture solar piles are galvanized to prevent corrosion. And not only is galvanizing expensive, but it can also cause environmental risks if zinc leaks into the ground water. According to Maguire, another benefit of Castrip is its natural anti-corrosion properties, meaning galvanizing isn’t needed.

“Corrosion-resistant steel is available on the market, but it’s only effective in certain environments. Castrip offers anti-corrosion for most environments, is low-energy, low-cost and highly sustainable, offering the solar industry a truly innovative solution ― if able to withstand loading. And that’s what our research set out to find.”

Enerpac hydraulic cylinder helps mimic lateral load in testing

To test the strength and global deformation of Castrip under loading, researchers used a three-point bend test. The solar piles were placed on their side and pressure was applied to the middle of the piles while being held up on both ends. From there, researchers monitored and recorded the rotation deformation at each of the three bending points ― left side, right side and center ― to determine how much the piles were moving during loading. And finally, the researchers measured how much the piles deformed in the direction of the load.

An Enerpac hydraulic cylinder helps mimic lateral load in the University of Nebraska-Lincoln’s solar panel pile testing

To help put pressure on the piles and mimic vertical loading, the test involved the Enerpac RR20013 double-acting, general purpose hydraulic cylinder ― 221 ton capacity and 13.00 in stroke ― that the university has been using for years to conduct tests as such. The linear motion and high force produced by the cylinder gave the researchers what they needed to add the appropriate amount of force to the three bending points. To prevent from accidental over-pressurization, the hydraulic cylinder features a built-in safety valve. The researchers also used Enerpac hand pumps to apply hydraulic pressure with even more accurate control and simplicity where needed.

Enerpac RR20013 double-acting, general purpose hydraulic cylinder

“The Enerpac equipment’s simplicity and reliability is why we’ve relied on it for decades to conduct tests. In addition, the service is extremely beneficial to the university. The territory manager will visit the lab regularly to conduct inspections, make equipment recommendations and train new students,” said Maguire. “And for a test like the solar pile research, easy-to-use equipment with dependable expertise is paramount.” The precision and combination of the Enerpac equipment allowed Maguire and his team to simulate environmental forces, producing accurate and consistent results.

“The preliminary results confirm that when Castrip is reshaped to unlock its optimum strength, the material mimics other steel on the market, but at a much lighter weight, and can withstand similar loading pressures as other materials,” said Maguire. “The results were astounding. We didn’t expect such a light-weight component to meet, let alone surpass, the performance of typical steel components.”

Preliminary results show promising future for new material

“We tested approximately 25 different piles, but Castrip kept performing time after time. After five rounds of testing, it proved to have a strength that is three times higher than typical steel shape,” said Maguire. “And, when Castrip deformed upon failure, it bounced right back to its original shape after the load was removed. The elasticity was incredible. It worked just like a rubber band.”

Testing hasn’t formally concluded, but Maguire is confident that the solar pile industry will potentially have a strong, high-performing material that meets modern sustainability expectations.

For further information about the research project, please contact Marc Maguire at marc.maguire@unl.edu

About Enerpac
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