Net metering calculator, Montana

How net metering works in Montana

A 50 kW cap applies specifically to NorthWestern Energy customers

NorthWestern Energy, Montana's largest investor-owned utility, caps net metering at 50 kW for residential installations, a limit well above what a typical rooftop system needs but worth knowing if you're planning a larger system. Montana-Dakota Utilities, the state's other investor-owned utility, operates under similar net metering rules. Full retail crediting itself isn't guaranteed forever: the Public Service Commission voted 5-0 to reject NorthWestern's past attempt to end net metering and add a demand charge, ruling the arrangement should hold until rooftop solar reaches 5% of NorthWestern's peak load. Solar currently sits around 1% of that load, so there's room to grow before the issue comes back up.

Credits are lost annually rather than rolling forward indefinitely

Excess generation credits roll forward from month to month within the year, letting summer surplus offset winter usage, but any credit balance still on the books at the annual true-up is lost rather than carried into the next year or paid out in cash. That makes sizing a system to closely match your annual usage more valuable in Montana than in states with indefinite rollover.

Aggregate net metering isn't currently allowed

Montana's net metering law doesn't currently permit aggregate net metering for NorthWestern Energy or Montana-Dakota Utilities customers, a matter the Montana Public Service Commission oversees, meaning credits from a single solar array can't be used to offset multiple separate electric meters, such as on a ranch or a property with several buildings. That's a real limitation compared to states that do allow this kind of arrangement, though Montana's tax credit and rebate estimator is worth checking regardless of how many meters you're offsetting.

Rural electric cooperatives set their own separate policies

If your provider is a rural electric cooperative rather than NorthWestern Energy or Montana-Dakota Utilities, the statewide net metering rules described here don't automatically apply. Cooperatives set their own net metering terms independently, so checking directly with your specific cooperative is the only reliable way to know your actual credit structure. Run the tax credit and rebate estimator with your own numbers before you decide.

Interconnection and the off-grid comparison

Whether NorthWestern Energy or Montana-Dakota Utilities serves your address, connecting a system runs through that utility's own interconnection application; the grid interconnection cost estimator covers what that process typically costs. And with monthly rollover already covering typical seasonal swings, staying grid-tied remains far cheaper than going fully off-grid in most of Montana; the grid tie vs off grid comparison tool shows how much cheaper. The credit rate only matters once it becomes a payback period. The payback period calculator in our Savings & Payback section can help you work out how long the system takes to pay for itself.