Solar Sanity Checksolar, decoded Independent. Nothing you type leaves your browser.

Northwestern Corporation

Montana Utility Interconnection & net metering rules
Net Metering Allowed1
NEM TypeAnnual
Line Taps Allowed1
Load Taps Allowed1
MPU Rules<p>If MPU is required, Northwestern Energy requires it to be
AC Disconnect RequiredYes

Net metering & export

Net Metering Allowed
1
NEM Type
Annual
TOU Utility
0
Post Solar Billing Method
Net Metering
Net Excess Generation Notes

If during the monthly billing period the electricity generated by the consumer is greater than what was consumed, the excess kWhs shall be carried into subsequent billing periods, until the consumption offsets the excess kWh balance or the time of the annual true up at the end of the designated 12 month billing period, which ever is earlier. At the annual true up, any excess kWh balance remaining will be granted to the utility with no compensation to the customer.

Rebates Offered
0
Deregulated
1
Allows Standby
1

Interconnection & taps

Approval Req To Install
Yes
Interconnection Level
3
Line Taps Allowed
1
Load Taps Allowed
1
MPU Rules

If MPU is required, Northwestern Energy requires it to be a minimum 200A Upgrade. This requirement is only when we are upgrading.

Automatic Transformer Upgrade Size
0
Meter Aggregation Allowed
0

System size & offset

System Size Restrictions
50
System Size Restriction Type
AC kW
System Size Battery Included
0
System Size Includes Existing Systems
0
Offset Type
No Restrictions
Offset Value
0
Offset Calculation Period
0
Industry Standard Watts Sqft
2
System Offset Notes

Up to 50 kW AC

NOTE:

-At the annual true up, any excess kWh balance remaining will be granted to the utility with no compensation to the customer.

Offset Calc Tool
Historical Usage

Metering & disconnect

Production Meter Required
No
Production Meter Criteria

PM socket is optional if the customer wants it. It is not a utility requirement. Please see plan examples uploaded to files

Production Meter Position
N/A
Production Meter Labeling
N/A
AC Disconnect Required
Yes
AC Disconnect Labeling
Visible Lockable Labeled Disconnect
Allowed Meter Adapter
None

Plans & docs

Site Plan Reqs

Standard - Must show distance between AC Disconnect and utility meter, if equipment is not grouped together. If grouped together a note stating equipment within 10' is adequate.

AC Disconnect Required

  • External, visible and lockable disconnect within 10 feet of the utility meter
  • If the AC Disconnect is not within 10 feet of the utility meter, the utility must approve the location prior to installation, which may require a utility site visit.
  • If seeking a variance from the 10 foot requirement, the installer must show the proposed location of the AC disconnect in the detailed site diagram, and include an explanation justifying the need to locate the AC disconnect more than 10 feet from the meter (including physical limitations).
SLD Reqs

Standard - Must show distance between AC Disconnect and utility meter

Electric Service Reqs

Install Reqs

Northwestern energy will not allow us to install on split structures IF the home has 2 or more meters - If it has 2 or more meters, the panels MUST be on the structure the meter we are offsetting is on. For example, if the home has 2 meters, one of the detached garage one on the main home, and the customer wants the panels on the garage but we are offsetting the main home meter, they will not allow this. Please message staff if you have any questions

Electrical Stamp Required
0
Equipment Approvals
California Energy Commission
Meter Num Req SLD 3LD
0
ESID Num Req SLD 3LD
0
Site Plan Notes


Cover Page Notes

remove Utility Meter number from all pages. (delete in relay)

Website
link
Phone
(406) 497-4165

Other details

Restrict Inspection
1
Revision Required
1
Mod Swap Requires Planset
1
Address ID
4737230
Express Planset Eligible
Yes
Compiled from public records, 2026. Tariffs and interconnection rules change; verify with Northwestern Corporation before you rely on this. The useful move: if an installer says you need a main panel upgrade, ask how these tap and interconnection policies were considered first.