UPS Distribution CenterSeptember 2012
When Bill Moir, the facilities manager for the United Parcel Service decided to install solar at their Parsippany, NJ distribution center, he knew right away he did not want to use a ballasted racking approach. UPS owns the building and has an interest in the long-term quality of the roof. Moir learned about Silverback Solar through a roof consultant’s recommendation and, after a thorough investigation, chose Silverback as the racking system for the UPS Parsippany plant. He was impressed with the watertight attachment system and the flexibility Silverback provided long-term. With Silverback’s elevated racking system UPS would be able to maintain, repair and even replace the roof if necessary without removal of the system.
Designing the solar array for UPS Parsippany was not without its challenges. The building was older and had limited capacity in the roof structure. Moir, concerned with the integrity of the roof, wanted to limit the number of penetrations while also maximizing the PV output. Additionally, there were significant wind and snow loads and hundreds of roof obstacles to contend with.
The engineering process was a balancing act of maximizing the PV output while managing layout issues. The Structural Engineers hired by UPS to verify the roof’s load capacity determined that the steel open web joists, originally built in 1974, could only handle limited point loads at specific locations along each joist. Through several design iterations and collaboration with the structural engineers, Silverback’s engineering team was able to provide a layout with the right balance of span distance, tilt angle, shadow spacing and point loading to maximize the PV density for the available roof space.
Silverback’s patented sprocket lock roof connections helped overcome the limitations of the existing roof structure by reducing the torsion loads into the joists, allowing for longer span distances and fewer penetrations than a traditional system would typically allow under these circumstances. The S32 frame chosen for this project was elevated over the piping and other roof obstructions, maximizing the available roof space. The final layout comprised over 4,400 PV modules with only 2,446 penetrations resulting in over 1 MW worth of solar power.
An important factor for UPS when choosing a racking system was the ability to install the array without disrupting production at the facility. Silverback was able to engineer the system so that all attachments were done from above the roof and there was no need to go into the building. This allowed production to continue without interruption.
Silverback worked closely with Pfister Energy, the installer, to ensure a timely and smooth installation. All of the parts were pre-assembled and the tubing was cut to length prior to shipping to expedite installation time. Christopher Grablutz from Pfister felt the racking was “very strong, stable and robust.” He went on to say that Pfister liked the flexibility that the Silverback system afforded them when installing and appreciated the clean, elegant look of the system.
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