Federal Way UMC Microgrid
Auburn, WA · Federal Way United Methodist Church · Operational Q3 2026
41.8 kW solar · 125 kW / 220 kWh storage · whole-site backup
Purpose
The church sits in unincorporated King County, next door to South King County Fire & Rescue Station 65, and already works as a regional support hub. It helps neighbors at risk of utility shutoff with their bills, provides evening meals and sack lunches for people staying at the Federal Way shelters, and sends weekend food backpacks home with children at Meredith Hill Elementary. Its sanctuary, prep kitchen, and dining room make it usable as a mass care facility, and the building is ADA accessible throughout, but it had no way to operate without the grid: no generator and no backup of any kind on site. A feasibility study completed by our sister company, Cascadia Renewables, under Commerce's Solar Plus Storage for Resilient Communities program established the case, and the microgrid followed.
Challenges
The whole building had to stay powered, not a critical-load panel, so a 600 A motorized breaker controlled by an SEL-751 relay went in on the line side of the existing main distribution panel. It isolates the church from the grid automatically during an outage and lets solar and battery carry the site. The larger constraint was upstream. The church's 600 A service was fed from a 25 kVA pole-mounted transformer, far too small to sit in front of a 125 kW battery inverter, so PSE had to upgrade the transformer before the system could run.
The array itself is attached to the standing seam metal roof using S5 clamps, avoiding the need to bolt through it, made possible by a 2010 roof replacement. Sized against the church's consumption history, the battery carries the building for more than 72 hours in a summer outage and around 34 hours in winter.
