Montana / Local permit guide
Billings Solar Permit Guide
Your local requirements. The official sources. A clearer next step.
- Permit authority
- City of Billings Building DivisionSource linked
- Electric utility
- NorthWestern EnergySource linked
- Local 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.Project-specific eligibility conditions apply.
- Review time
- 4–7 daysSee source scope and conditions below.
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Research coverage
Your permit path,
at a glance.
This shows what GridPermit has verified for Billings. It does not show the status of a specific project.
01 / Know your path
Two approvals.
One project.
A local permit and utility permission to operate are different approvals. Check the local sequence and requirements below.
How to read this guide
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. Some supporting official material could not be independently confirmed from the full source in GridPermit's latest review. Verify the current requirement with the authority before relying on it.
Sources & confidence
Battery/solar incentive program on record
No battery/storage incentive program is on record for this locality.
02 / Prepare your application
What you need.
Sources & confidence
Permit fees
Some supporting official material could not be independently confirmed from the full source in GridPermit's latest review. Verify the current requirement with the authority before relying on it.
- 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.
Sources & confidence
Rebates on record
Rebates on record
Not yet verified.
Utility and generation supplier
Utility
NorthWestern Energy
NorthWestern Energy is the well-established dominant electric utility for Billings, Montana's largest city.
Sources & confidence
Generation supplier
NorthWestern Energy (utility)
NorthWestern Energy is recorded as both the distribution and generation utility.
Sources & confidence
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).
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.
Sources & confidence
Official contacts
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 links to EnergySage as an independent third-party resource. This link is not currently tracked for compensation.
Official sources
Official 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 same utility is also listed as the default electricity generation supplier.
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. Some supporting official material could not be independently confirmed from the full source in GridPermit's latest review. Verify the current requirement with the authority before relying on it.
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.