How is system size measured for interconnection in Montana?

The published limits are stated in kilowatts without saying whether that is the inverter alternating current rating or the array direct current rating.

Is this address served by a rural electric cooperative? Montana net metering does not apply to them at all, by an applicability section that says so in one sentence.

Only the utility holds this figure. Ask before you quote the job.

What is your filed schedule of interconnection processing fees and study rates? Montana requires each utility to file one with the Commission and publishes no amounts itself.

Only the utility holds this figure. Ask before you quote the job.

Montana solar interconnection rules, tiers and fees

How the size is measured: not published

The published limits here are stated in kilowatts without saying whether that is the inverter rating in alternating current or the array rating in direct current. On a system near a threshold that decides which band it lands in, so the checker asks the question rather than choosing an answer.

Size bands and what each one obliges

Level 1 Size 0 to 10 kW	A nameplate capacity of 10 kW or less with certified equipment. Montana publishes no fee amounts and no insurance requirement at any level; each utility files a fee schedule and study rates with the Commission after public notice. Certified equipment Fee per the utility filed schedule No insurance published in the rule
Level 2 Size 10.001 to 2000 kW	A nameplate capacity of 2 MW or less with certified equipment. Certified equipment Fee per the utility filed schedule
Level 4 Size 2000.001 to 10000 kW	Anything that does not meet the criteria for expedited review under the lower levels, up to the 10 MW aggregate nameplate ceiling of the rules. Study process Fee per the utility filed schedule

Level 1 Size 0 to 10 kW

A nameplate capacity of 10 kW or less with certified equipment. Montana publishes no fee amounts and no insurance requirement at any level; each utility files a fee schedule and study rates with the Commission after public notice.

Certified equipment
Fee per the utility filed schedule
No insurance published in the rule

Level 2 Size 10.001 to 2000 kW

A nameplate capacity of 2 MW or less with certified equipment.

Certified equipment
Fee per the utility filed schedule

Level 4 Size 2000.001 to 10000 kW

Anything that does not meet the criteria for expedited review under the lower levels, up to the 10 MW aggregate nameplate ceiling of the rules.

Study process
Fee per the utility filed schedule

The screens that decide it

Within the 50 kW net metering limit Limit 50 kW.
A Montana net metering system must use solar, wind or hydropower as its fuel and have a generating capacity of not more than 50 kilowatts. The fuel list excludes biomass and geothermal, and the interconnection right survives above 50 kW even though net metering does not.
Aggregate generation on a shared secondary under 20 kVA Limit 20 kW.
Montana caps aggregate capacity on a shared secondary line at 20 kilovolt-amps, and separately requires that generation not exceed the capacity of the customer existing electrical service.
Aggregate generation under 15 percent of line section peak or the annual minimum load 15 percent of line section peak load, a figure only the utility holds.
Montana states both tests together: aggregated generation on the line section may not exceed 15 percent of line section annual peak load or the annual minimum load of the line section. A spot network is separately limited to 5 percent of maximum load.

Ask the utility this, before you sell it

Is this address served by a rural electric cooperative? Montana net metering does not apply to them at all, by an applicability section that says so in one sentence.
What is your filed schedule of interconnection processing fees and study rates? Montana requires each utility to file one with the Commission and publishes no amounts itself.
What is the line section annual peak load and the annual minimum load? Montana names both in the same screen.

Worth knowing before you quote

Montana publishes no insurance requirement and no prohibition, and no aggregate net metering cap of any kind, both confirmed by reading the rules and all five statute sections. Storage sits inside the definition of a small generator facility, which covers production, or storage and production, or storage alone. Level 3 is the non export track, up to 10 MW aggregate on a radial circuit and 50 kW on an area network, using reverse power relays or other protection that prevents export. Timelines are in business days: ten for completeness, fifteen more to verify, five to issue an agreement, thirty for the customer to sign, and twenty five for an area network impact study.

Utility programs we have read in Montana

Flathead Electric Cooperative generation interconnection

Source

Montana Administrative Rules 38.5.8401 through 38.5.8413, small generator interconnection, effective 13 August 2010, with Montana Code Annotated 69-8-601 through 69-8-605

Read and recorded 2026-09-12. Binds an electric distribution company, defined as an electric utility distributing within Montana and subject to Commission regulation, so investor owned utilities only. The net metering statute is blunter still: its applicability section reads in full that the part does not apply to corporations organized under Title 35 chapter 18, which are the rural electric cooperatives. Montana cooperatives are outside net metering entirely.

Solar and battery interconnection rules in Montana

Size bands and what each one obliges

The screens that decide it

Ask the utility this, before you sell it

Worth knowing before you quote

Utility programs we have read in Montana

What to do with this