Structural Solutions: Tricky solar sites resolved by growing and racking systems

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Massive, sprawling solar projects on smooth landscapes are no longer the standard. For solar energy to reproduce across the country, PV systems require to attach to various distant environments — oddly shaped parcels, rough terrains, confined city corners, blocked roofs and so on. Fortunately, there are more solutions for resolving these site challenges than ever before. Here are some examples.

Amphenol Solar Project

Challenge: The Amphenol site was a Department of Environmental Conservation-listed brownfield and had been a manufacturing site for 80 years. The manufacturing plant had also suffered significant damage during two major flooding events within the past decade. The flooding and environmental concerns made for a complex project.

Structural solution: Hybrid Solution using Solar FlexRack G3P-X and B3X Cast-In-Place (CIP)

How it helped: While Amphenol had cleared the site of old manufacturing buildings, four concrete slab foundations remained. EnterSolar, the solar developer, was careful not to breach the concrete slabs of the environmentally sensitive site and sought racking solutions through Solar FlexRack, which utilized a unique ballasted system wherever necessary. The ballasts were dowelled into the slabs beneath to help reduce concrete requirements. For the areas where the array was built over the ground without the concrete slabs underneath, the system incorporated a driven pile method.

The solar project was built to meet 500-year-event flood standards, which ultimately resulted in an increased height threshold for all of the solar panels. With both environmental concerns and floodplain conditions, a hybrid racking solution was needed to support the entire system that included outside-the-box techniques, such as increasing the length of the piles and switching up racking technologies. By using both driven piles and CIP foundations, the Solar FlexRack team was able to accommodate the dynamic landscape.

“For this project, the embedment depth alone was 15.5 ft. The majority of driven posts on standard projects are about 14 ft total,” said Steve Daniel, EVP of Solar FlexRack. “We compensated for extremely weak soils by going deeper, which required special equipment, and then had the additional issue of floodplain ground clearance. The total post length of these piles was 22 ft.”

Amphenol is helping New York State work toward achieving its ambitious sustainability goals through generating clean, renewable energy onsite in Sidney. The company’s solar system demonstrates a continuing commitment to manufacturing in the state and support of its dedicated employees and the local community.

Northwest Media

Challenge: The building owner wanted solar, but his building simply was not ideal for solar. First, the building did not have a true southern facing roof orientation. Second, during the roof survey it was determined that the roof could not handle a significant load beyond the weight of the solar panels, so a dual-tilt ballasted system was not a viable option.

Structural solution: SunModo‘s SunDock Elevated Dual-tilt

How it helped: The installer contacted SunModo and asked if a cost-effective racking solution could be designed. After a conference call with the stakeholders, SunModo proposed installing its SunDock Elevated Dual-tilt System. The SunDock Elevated Dual-tilt System has several features that made it a better solution for this job than a conventional ballasted or roof attached system.

The elevated dual-tilt system reduces the number of roof attachment required because the structural beams allow for long spans between attachments. And because the elevated system is entirely aluminum, the overall racking weight is significantly reduced when compared to concrete ballast blocks.

The solar panels are attached to the dual-tilt supports, which position the panels at the desired 10-degree angle.

The bases of the dual-tilt supports are attached to aluminum extruded rail, which are secured to structural beams. The structural beams and the aluminum rail provide a light weight, long-span solution, thereby minimizing the number of roof penetrations required.

Since the solar panels are elevated, localized waves in the roof are not a problem. And because the array is elevated, the underside of the solar panels stays cooler, which increases the solar panels efficiency.

Montserrat Utilities Limited, Government of Montserrat

Challenge: The Montserrat project involved providing solar for three government buildings normally powered by high-cost power from diesel generators. Numerous project challenges included the roof profile (a face-attached panel), the age of the roof (15 years), design wind load requirements (hurricane-prone area) and shipping logistics (Montserrat is an island).

Structural solution: S-5! RibBracket III and PVKIT 2.0 Solar Attachment

How it helped: The 15-year-old, obsolete trapezoidal roof profile limited the customer’s options for mounting solar as few products exist for this particular roof profile without custom-designing an expensive solution. S-5! offers many tested solutions for any trapezoidal profile and the PVKIT 2.0 provided a rail-less, direct-attach solution comprised of pre-assembled components. The design wind load requirements also necessitated a product capable of withstanding Category 5 hurricane winds. S-5! products can be engineered to meet the high end of this category at 180 mph (290 km/h) winds.

A traditional, three-rail system would have involved 10,000 ft of rail and required a full 40-ft container to ship. S-5! provided six attachments per module shipped on one standard palette — a 50 percent savings on product cost and 70 percent on shipping.

Furthermore, the labor to install a rail-free system costs less than adding rails. The S-5! PVKIT uses the ribs of the roof as the rails, providing flexibility every 12 in. for placing the attachments directly into the roof. This distributed the load more prudently and uniformly into the trapezoidal panels, also by staggering the attachments on alternating ribs.

Southern New Hampshire University

Challenge: There were many challenges constructing a solar carport atop the Southern New Hampshire University (SNHU) parking garage: extreme conditions related to snow loads of 70 psf and wind speeds of 115 mph and the need to work alongside the general contractor and development company actually building the six-story parking garage from the ground up with a tight timeline. These challenges were combined with the structural constraints of attaching to the existing columns on the top of the garage that are ever present in garage projects. Since this garage was an active construction site located in downtown Manchester, sandwiched between a stadium, SNHU and the Merrimack River, there was little to no additional space to have the carport structure built on ground level. The construction zone was limited to the exact overall dimensions of the carport with only about a 3-ft perimeter around the working space.

Structural solution: Quest Renewables‘ QuadPod

How it helped: The garage only allowed for lightweight scissor lifts and forklifts, conditions that typically present large barriers to steel construction. The complete system was constructed on the ground and then lifted by crane for final attachment to the two columns atop the parking garage.

To solve the site challenges, the project engineers began with QuadPod’s standard design configuration. Every garage has its own nuances, and in this case, the top of the deck was equipped with two columns spaced 42 ft apart. With the system’s flexibility, the engineers had the ability to adjust the system to the width of the existing garage columns. The adjustable span design allowed for attachment of the canopy to the two existing columns.

Lastly, engineers needed to ensure the system would be strong enough to handle the loads, and the typical response would be to create a stronger structure. Because this system is constructed as a three-dimensional truss, certain members can be reinforced where necessary and additional steel added where most effective. The Quest team was able to use relatively lightweight members to support the heavy load without compromising the garage’s stability.

The project wrapped up in the spring of 2019 just a few days away from opening day at Northeast Delta Dental Stadium. If there had been delays in construction or if the weather had prevented the craning of the structure up to the roof, there were would have issues preventing previously scheduled opening day events.

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