NorthWestern Energy
Improved Reliability – Rural Community
Microgrid: Solar | Battery | Grid Power

NorthWestern Energy – Rural Microgrid
Deer Lodge, Montana – U.S.A.

WRH Power Systems has constructed and currently maintains NorthWestern Energy’s Microgrid comprised of 80 kVA/183.4kWh (8-hour rate @ 80% depth of discharge) of battery storage as well as an additional 40.26 kW of solar photovoltaic (29.28 kW DC Coupled & 10.92 kW AC Coupled). The Microgrid serves customers on a radial distribution circuit north and west of Deer Lodge, Montana and offers both customer and grid benefits.

When the Microgrid is grid connected to the feeder circuit, the grid provides energy to the loads, including charging of the batteries as needed. If the sun is available, the Solar PV provides support to the grid and charges the batteries as needed. The battery inverters can be placed in sell-back mode, allowing the batteries to push stored energy onto the grid. This, in turn, simulates peak shaving, or if set prior to available solar, can simulate load-shifting by discharging the batteries during non-PV production hours and absorbing energy during PV-production hours. When customers in the Microgrid area lose utility power, the Microgrid, automatically islands from the utility providing reliable continuous power. Once utility power is restored, the Microgrid automatically reconnects to the utility. Batteries are sized to support the customers for 2 hours under max load conditions.