Billings Solar Permit Guide
NorthWestern Energy territory · Yellowstone County
Overview
GridPermit collects Montana residential solar and permitting facts directly from official sources (city, county, and state government sites, utilities, and public utilities commissions) and shows only what we can verify, with a confidence score and a link to where it came from. Nothing here is estimated or inferred beyond what's stated below. See our methodology for the rules this page follows.
Permit timeline
4–7 days
Per the City of Billings' own FAQ ('How long will it take to get a building permit?'), verbatim: 'Once a complete plan has been submitted, and special issues have been addressed... the initial review takes: Residential (single-family and duplex): 4-7 business days.' This is the general residential building-permit initial-review window, not a solar-specific figure. A previous research pass this session found this same figure only via third-party aggregator results and correctly left it unconfirmed; it has now been directly confirmed on the City's own FAQ page.
Battery/solar incentive program on record
No battery/storage incentive program is on record for this locality.
Permit fees
- NorthWestern Energy Level 1 interconnection processing fee: $200 (one-time, non-refundable, must accompany the Interconnection Request)
Per NorthWestern Energy's own Level 1 Small Generator Facility Interconnection Request form.
Rebates
Not yet verified.
Utility and generation supplier
Utility
NorthWestern Energy
Generation supplier
NorthWestern Energy (utility)
NorthWestern Energy is recorded as both the distribution and generation utility.
Interconnection
NorthWestern's own separate 'Home Solar Information' page explicitly states: 'NorthWestern Energy does not offer incentives for solar installations for residential customers,' and confirms net metering credits accumulate as a kWh balance that is available toward future bills only until the customer's selected annual settle-up month, at which point Montana law mandates the excess credit balance resets to zero (no rollover past that date, no cash-out).
Required documents
- Detailed site plan (home/structure, electrical service meter, main service panel, interconnected sub-panels, all PV components, structure and panel square footage, IRC fire access pathways and ridge setbacks) (required when: always)
- Mounting system evaluation by a Montana-licensed Professional Engineer (using minimum 30 psf non-reducible roof snow load, 110 mph ultimate wind speed, Exposure Category C) (required when: always)
- One-line diagram (PV system type, module count/layout, circuit type, conductor/conduit sizing and types, equipment grounding conductor, fuse/breaker ratings) (required when: always)
- Interconnected-components documentation with NEC Article 705 code references, plus photos of the meter main and interconnection point panels (overall view and manufacturer specification labels) (required when: always)
- Site-specific equipment labeling diagram, including the NEC 705.10 directory ('typical'/generic labeling diagrams are not accepted) (required when: always)
- Module specification sheets (UL 1703 listed) and inverter specification sheets ('utility interactive,' UL 1741, ground fault protection, rapid shutdown compliance) (required when: always)
- NorthWestern Energy Level 1 Small Generator Facility Interconnection Request form, with equipment component list, one-line diagram, detailed site diagram, and product specification sheets (required when: always)
- Exhibit A — Net Meter settle-up month selection (January, April, July, or October) (required when: always, for installations requiring a net meter)
Inspection steps
Not yet verified.
Eligibility constraints
- Property types: residential
- Max system size (AC): 50 kW
- Max system size (DC): Not yet verified.
- Max thermal capacity: Not yet verified.
- Program/pathway: NorthWestern Energy's Level 1 Small Generator Facility Interconnection process — for systems with aggregate nameplate capacity (generation plus storage) of up to 50kW-AC using certified, publicly listed interconnection equipment.
- Other conditions:
- Net-metered facilities may only be fueled by solar, wind, and/or hydropower, per NorthWestern's own interconnection form.
- An external, visible, lockable AC disconnect switch must be located within 10 feet of the utility meter, unless NorthWestern Energy grants a case-by-case variance for a different location.
- The customer must select an annual 'settle-up' month (January, April, July, or October); any unused excess energy credit balance resets to zero at that date, per Montana law — no ongoing rollover or cash-out.
- NorthWestern Energy's own materials state it does not offer incentives for residential solar installations.
- City of Billings mounting-system engineering calculations must use a minimum 30 psf non-reducible roof snow load, 110 mph ultimate wind speed, and Exposure Category C.
Official contacts
- City of Billings Building Division, phone: 406-657-8433, official website
- NorthWestern Energy Interconnection Department, phone: 406-497-4165, email: northwesternenergynetmeter@northwestern.com, official website
Need a solar installer who handles permits in Billings?
EnergySage is an independent solar marketplace where you can request property-specific pricing from installers familiar with local permitting.
Compare quotes from solar installers →You'll continue on EnergySage's website. GridPermit has a partner relationship with EnergySage; this link is not currently tracked, and whether the partnership results in compensation to GridPermit has not yet been confirmed.
Sources
- Solar-Photovoltaic System Plan Requirements (02/23), City of Billings, MT, Building Division (government). Accessed 2026-08-14.
- Level 1 Small Generator Facility Interconnection Request (Revision 1/23), NorthWestern Energy (utility). Accessed 2026-08-14.
- FAQs - How long will it take to get a building permit?, City of Billings, MT, Building Division (government). Accessed 2026-08-14.
Frequently Asked Questions
What utility serves solar customers in Billings, Montana?
NorthWestern Energy is the interconnection and distribution utility for Billings. The default electricity generation supplier is NorthWestern Energy, a utility, separate from NorthWestern Energy.
How long does a residential solar permit take in Billings?
Per the City of Billings' own FAQ ('How long will it take to get a building permit?'), verbatim: 'Once a complete plan has been submitted, and special issues have been addressed... the initial review takes: Residential (single-family and duplex): 4-7 business days.' This is the general residential building-permit initial-review window, not a solar-specific figure. A previous research pass this session found this same figure only via third-party aggregator results and correctly left it unconfirmed; it has now been directly confirmed on the City's own FAQ page.
What documents are required for a solar permit in Billings?
Commonly required documents include: Detailed site plan (home/structure, electrical service meter, main service panel, interconnected sub-panels, all PV components, structure and panel square footage, IRC fire access pathways and ridge setbacks); Mounting system evaluation by a Montana-licensed Professional Engineer (using minimum 30 psf non-reducible roof snow load, 110 mph ultimate wind speed, Exposure Category C); One-line diagram (PV system type, module count/layout, circuit type, conductor/conduit sizing and types, equipment grounding conductor, fuse/breaker ratings); Interconnected-components documentation with NEC Article 705 code references, plus photos of the meter main and interconnection point panels (overall view and manufacturer specification labels); Site-specific equipment labeling diagram, including the NEC 705.10 directory ('typical'/generic labeling diagrams are not accepted); Module specification sheets (UL 1703 listed) and inverter specification sheets ('utility interactive,' UL 1741, ground fault protection, rapid shutdown compliance); NorthWestern Energy Level 1 Small Generator Facility Interconnection Request form, with equipment component list, one-line diagram, detailed site diagram, and product specification sheets; Exhibit A — Net Meter settle-up month selection (January, April, July, or October).
Who do I contact about solar permits in Billings?
City of Billings Building Division, phone 406-657-8433.