Case Study
Designing a Resilient System Requires a Resilient Team
Oregon Military Department Readiness Center
Project Highlights
Location
Dallas, OR
System Specs
255 kW PV array (existing), 180 kWh energy storage (new), 90 kW hybrid inverters (new)
Equipment
Princeton PEMS 30 kW / 60 kWh battery bank Princeton PEMS 60 kW / 120 kWh battery bank Ageto microgrid controller
Challenge
The Oregon Military Department (OMD) wanted to bolster the resiliency of its Col. James W. Nesmith Readiness Center. The facility already had a 255 kW PV array and a 150 kW diesel generator, but in the event of an earthquake or long-duration grid power outage, the PV system would be inoperable, leaving just the generator’s 1,000-gallon tank. OMD wanted an energy storage system (ESS) to optimize the existing on-site assets and boost its backup power capacity to 14 days, as well as provide a blueprint for installations at other facilities.
Retrofitting a long-duration ESS to a grid-tied PV system at a facility this size that also includes a generator was a considerable challenge. The installer, Sunlight Solar, contacted Mayfield Renewables in 2018, and asked us to conduct the feasibility study and take on the design.
Solution
For the feasibility study, we installed load monitoring devices and gathered several months of on-site production and usage data. We then used that information to simulate three potential energy storage systems at three times of year—January, April, and August.
Once the equipment decisions had been made, we produced CAD drawings, designing plan sets and ensuring code compliance and approval from the authority having jurisdiction (AHJ).
We plan to tell this important story to the community we serve—the energy efficiency and net zero capacity that we have built into the facility and why.
Kenneth Safe
Construction & Facility Management Officer; the Oregon Army National Guard
Project Hurdles
Energy Storage Selection
For a commercial and industrial (C&I) storage project of this size, product availability was fairly limited. Site-specific details often dictate equipment choices. In this case, OMD wanted enough ESS capacity to accept the full 255 kW of existing solar PV generation, and to install the ESS inside an electrical room.
Feasibility modeling ruled out one of the ESS options, as it could only accept 150 kW of the existing 255 kW solar array. With safety in mind, we selected an ESS with a more thermally stable chemistry and adhered to unit spacing and setback requirements for indoor ESS installations.
Code Compliance
The design originally called for the generator to be able to charge the battery bank while it was running. But Code requirements for interfacing with an “emergency panel” are very specific, and were written for large engine generators, not energy storage systems.
We isolated the existing generator from the rest of the system, leaving the “emergency” side of the automatic transfer switch alone. This resulted in a near-total redesign and the need for a little more generator fuel.
Result
The full design process took about eight months, followed by three months for the AHJ to sign off on the plan set and another three months for utility approval.
In addition to extending the facility’s outage capability to 14 days, the system is designed to use the battery every day to reduce peak loads and save OMD about $2,000 a year. Also, because OMD intended to use this as a model project, we produced a “lessons learned” document to avoid some of the trial and error that was necessary on this project.
