What NEC edition does Missouri use for solar permits in 2026?

It depends on the jurisdiction. Missouri has no statewide building code for private residential construction — each city and county independently decides whether to adopt building and electrical codes, and which edition to use. Kansas City has adopted NEC 2020. St. Louis City adopted NEC 2017 effective August 2018. Many major suburban municipalities in St. Louis County and Jackson County have adopted NEC 2020 or 2023 with local amendments. Some rural unincorporated counties have no adopted electrical code at all, in which case local AHJ standards or state modular construction code provisions may apply. Every Missouri plan set starts with a local code lookup for the specific jurisdiction.

Does Missouri have a statewide building code?

No. Missouri is one of only a handful of large states without a mandatory statewide building code for private residential construction. Each of Missouri's 114 counties and hundreds of municipalities independently decides whether to adopt building codes and which editions to enforce. Major metro jurisdictions like Kansas City, St. Louis, Springfield, Columbia, and Independence have active building departments enforcing current or near-current International Code editions. Many rural and unincorporated areas have no formal building code. This creates one of the most complex AHJ landscapes in the Midwest for solar permit documentation.

Does Missouri have net metering?

Yes. Missouri's Easy Connection Act (RSMo §386.890) requires all investor-owned utilities, municipal utilities, and rural electric cooperatives to offer net metering for systems up to 100 kW. The law mandates identical rates and charges to non-solar customers and prohibits unique fees for customer-generators. Ameren Missouri and Evergy are the two major IOUs subject to MoPSC oversight. Monthly excess generation credits roll forward on the bill. At year-end, any remaining credit balance is reconciled at the utility's avoided-cost rate — not at full retail — meaning Missouri net metering is not a 1:1 retail-rate program.

How does Ameren Missouri's net metering work?

Ameren Missouri credits net excess solar generation monthly against the customer's energy charges at the retail rate during the billing month. If monthly solar production exceeds consumption, the excess kilowatt-hours are credited at the retail rate and carried forward to the next month. At the annual true-up, any remaining unused credits are paid out at Ameren's avoided-cost rate — approximately 2.5 to 4 cents per kilowatt-hour — rather than at the retail rate of approximately 14 cents. This means Missouri solar proposals should be sized to maximize self-consumption during the year rather than exporting large amounts that will be reconciled at avoided cost.

What utilities serve Missouri solar customers?

Missouri has two major investor-owned utilities: Ameren Missouri, which serves approximately 1.2 million customers in St. Louis and eastern and central Missouri, and Evergy, which includes Evergy Missouri Metro (about 310,000 customers in the Kansas City metro) and Evergy Missouri West (southwest Missouri). Liberty Utilities, through its Empire District subsidiary, serves the Joplin and southwest Missouri area. City Utilities of Springfield and Independence Power and Light are major municipal utilities with their own solar programs. Approximately 47 rural electric cooperatives serve rural and suburban areas with locally governed net metering policies.

What building codes apply to Missouri solar installations?

It varies entirely by jurisdiction. Kansas City enforces NEC 2020 and the 2021 IBC and IRC with local amendments. St. Louis City enforces NEC 2017 (adopted August 2018) and 2018 IBC. St. Louis County and most suburban municipalities have adopted 2021 I-Codes with various local amendments. Springfield and Columbia have adopted current or near-current I-Code editions. Rural and unincorporated counties may have no adopted building code. For Missouri solar permits, the first step is always a local jurisdiction code lookup — there is no statewide baseline that applies universally.

How does Missouri's Easy Connection Act affect solar permitting?

Missouri's Easy Connection Act (RSMo §386.890) simplifies the interconnection process for small solar systems. For systems 10 kW or less, the application must use a single all-in-one document covering interconnection request, procedures, and terms. Utilities must respond within 30 days for systems 10 kW and under and within 90 days for systems between 11 kW and 100 kW. The law prohibits utilities from charging standby, capacity, or interconnection fees not applicable to non-solar customers. Ameren Missouri requires a wiring diagram and equipment specification sheets with the interconnection application, plus a certification from a licensed electrician or engineer.

What solar incentives are available in Missouri in 2026?

Missouri offers a property tax exemption for solar energy systems used for on-site electricity generation. Missouri's renewable energy standard (Proposition C) requires IOUs to obtain 15% of electricity from renewables by 2021 — a mandate that is effectively achieved, meaning no active solar incentive is tied to RES compliance. No Missouri state income tax credit for solar exists. The federal Section 25D residential clean energy credit ended for systems placed in service after December 31, 2025. Some utilities offer modest efficiency rebates but no direct solar installation incentives. Ameren Missouri has active solar procurement programs but these are utility-scale, not residential incentives.

Why does Missouri's lack of a statewide code matter for solar plan sets?

It means the plan set must be built to the specific jurisdiction's adopted code, not a statewide default. A residential solar project in Kansas City requires NEC 2020 documentation. The same project across the county line in an unincorporated rural area may require no electrical permit at all. A project in St. Louis City references NEC 2017. A Springfield project references the city's adopted NEC edition with Springfield-specific amendments. A plan set built to the 'Missouri standard' doesn't exist — there is no such standard. Permit Design verifies the specific municipality or county's adopted code before building any Missouri plan set.

How long does it take to get a Missouri solar permit plan set?

Permit Design delivers Missouri solar permit plan sets within 24-48 hours. Every plan set starts with a jurisdiction-specific code verification — confirming the NEC edition and structural code adopted by the specific city or county — before any documentation is built. Interconnection paperwork is formatted for the confirmed utility, whether Ameren Missouri, Evergy, a municipal utility, or a rural electric cooperative. Free revisions until the Missouri local AHJ approves.

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St. Louis Metro · NEC 2020 · Ameren Missouri · City ≠ County AHJ · MO/IL Bi-State

St. Louis Solar Permit Design.
Ameren Missouri Net Metering. City ≠ County AHJ · Metro East IL Side Too.

St. Louis solar permit drawings for St. Louis City, St. Louis County, and Metro East. Key distinction: St. Louis City and St. Louis County are completely separate jurisdictions. Ameren Missouri net metering at retail rate. Metro East (Belleville, O'Fallon) is Ameren Illinois with different state rules. NEC 2020. Missouri property tax exemption. Free for first-time clients.

⚡ Order Your St. Louis Plan Set Ameren MO + City vs County AHJ ↓

Ameren MO Retail net metering · MO law

City ≠ County Separate AHJs · Confirmed per address

MO/IL Bi-State Metro East is IL · Different rules

Free AHJ revisions

Ameren MO NEMRetail rate · Required by MO law

City ≠ CountySeparate AHJs · St. Louis unusual structure

Metro East ILDifferent utility, state, building dept

24–48 hrStandard plan set delivery

2026 CodesElectrical: NEC 2020 (Missouri and Illinois)Structural: IBC/IRC 2018 (MO)Utility: Ameren Missouri (MO side) · Ameren Illinois (Metro East IL side)Key: St. Louis City and St. Louis County are separate independent jurisdictions in MissouriLast verified July 2026

Ameren Missouri Net Metering + St. Louis City ≠ County + Bi-State Metro

St. Louis City and St. Louis County Are Completely Separate Jurisdictions. Metro East Is Illinois. Ameren Missouri and Ameren Illinois Are Different Companies. Confirm Per Address Before You Build.

Ameren Missouri serves St. Louis City, St. Louis County, and most of Missouri with net metering at the full retail rate, as required by Missouri law. St. Louis City is an independent city in Missouri — it is not part of St. Louis County, an unusual legal structure that creates two completely separate building jurisdictions in the same metro. Metro East (Belleville, O'Fallon, Edwardsville, Alton on the Illinois side of the Mississippi) is Ameren Illinois territory with different state regulatory requirements, different net metering rules, and different AHJs. We confirm the state side, utility, and AHJ per address before building every St. Louis plan set.

Ameren Missouri · Net Metering at Full Retail Rate · Required by MO Law

✅Ameren Missouri net metering: credits solar exports at full retail electricity rate

✅Missouri law requires Ameren Missouri to offer net metering for residential solar

✅Ameren Missouri interconnection: submit simultaneously with building permit

⚠️Metro East addresses (Illinois side) use Ameren Illinois — different company, different rules

✅Missouri property tax exemption for solar energy systems — permanent

St. Louis City ≠ St. Louis County · Metro East IL · NEC 2020

⚠️St. Louis City is an independent city NOT part of St. Louis County — separate AHJs

⚠️St. Louis City Building Division ≠ St. Louis County Building — routing wrong = rejection

⚠️Metro East (Belleville, O'Fallon, Edwardsville) is Illinois — Ameren Illinois, IL building codes

⚠️Clayton, Kirkwood, Webster Groves are incorporated county cities with own building departments

✅NEC 2020 adopted in both Missouri and Illinois

⚠️ St. Louis City and St. Louis County are legally separate jurisdictions — and the Metro East is a different state entirely. St. Louis City Building Division covers city addresses. St. Louis County Building has its own department for county unincorporated areas. Metro East addresses are in Illinois, served by Ameren Illinois, and permitted under Illinois building codes. We confirm jurisdiction and utility for every St. Louis metro address before building.

Why St. Louis Installers Outsource

City vs County AHJ Confusion. Metro East IL Side Missed. Ameren MO vs IL Mix-Up.

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Routing St. Louis City Address to St. Louis County Building — or Vice Versa

St. Louis City is an independent city legally separate from St. Louis County. St. Louis City Building Division covers city-limit addresses. St. Louis County Building covers unincorporated county areas. Incorporated county cities (Clayton, Kirkwood, Webster Groves, etc.) each have their own departments. Routing to the wrong jurisdiction results in immediate rejection — no overlap in authority.

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Metro East Is Illinois — Different Utility, State Laws, and Building Departments

Belleville, O'Fallon, Edwardsville, Alton, and other Metro East communities are in Illinois. They are served by Ameren Illinois (not Ameren Missouri), permitted under Illinois building codes, and subject to Illinois net metering rules. A Missouri-formatted plan set with Ameren Missouri documentation submitted for a Belleville IL address is wrong on all counts.

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Ameren Missouri vs Ameren Illinois — Different Companies With Different Programs

Ameren Missouri and Ameren Illinois are separate operating companies under the Ameren Corporation umbrella. They have different rate structures, different interconnection applications, different net metering programs, and different customer contacts. An Ameren Missouri interconnection application submitted for an Ameren Illinois address is rejected by the wrong company entirely.

St. Louis Solar Permit Services

Ameren Missouri Interconnection. NEC 2020. All St. Louis AHJs.

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St. Louis Residential Solar Permit Design

NEC 2020, IBC/IRC 2018. Ameren Missouri or Ameren Illinois interconnection confirmed per address. St. Louis City, St. Louis County, or Metro East AHJ confirmed. Battery (NEC 2020 Article 706) where included.

NEC 2020Ameren MO or ILAHJ Confirmed

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St. Louis Commercial Solar Permit Design

Commercial rooftop drawings for St. Louis metro. NEC 2020, IBC 2018. Ameren commercial interconnection. St. Louis's healthcare, biotech, financial services, and logistics sector creates commercial solar demand. PE stamp. Mid-American ASCE 7 wind calcs.

IBC 2018Healthcare / BiotechPE Stamp

Commercial Solar Permit Design Services →

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St. Louis Battery Permit Plans

Solar-paired and standalone battery permit drawings. NEC 2020 Article 706. St. Louis's severe spring thunderstorms, occasional tornadoes, and summer grid stress create battery resilience demand. Battery maximizes self-consumption under Ameren net metering.

NEC 2020 Art.706Storm ResilienceAmeren Storage

Battery Storage Permit Design Services →

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St. Louis EV Charger Permit Design

EV charger permit drawings for St. Louis metro. NEC 2020 Article 625. St. Louis's healthcare, university, and logistics sector drive commercial fleet EV demand. Residential EV growing in St. Louis County suburbs — Chesterfield, Ballwin, Wildwood, and Clayton.

NEC 2020 Art.625Healthcare FleetLoad Calcs

EV Charger Permit Design Services →

St. Louis Solar Market — 2026

Four Things That Define Solar in St. Louis.

City ≠ County

St. Louis City and St. Louis County — Completely Separate Jurisdictions

St. Louis City is an independent city in Missouri that is legally separate from St. Louis County — a historical quirk from the 1876 Scheme of Separation. St. Louis City Building Division handles city permits. St. Louis County Building handles unincorporated county areas. Incorporated county cities (Clayton, Kirkwood, Ladue, Webster Groves, etc.) maintain their own building departments. Understanding the city-county separation is fundamental to correct AHJ routing in the St. Louis metro.

Ameren MO NEM

Ameren Missouri Net Metering — Full Retail Rate Required by State Law

Ameren Missouri offers net metering at the full retail electricity rate as required by Missouri law. Missouri's net metering policy protects solar owners' ability to receive retail rate credits for solar exports. Ameren Missouri serves approximately 1.2 million electric customers in Missouri. Rising Ameren Missouri rates improve solar ROI year over year.

Metro East IL

Metro East Is Illinois — Different Rules, Different Utility, Different AHJs

The Illinois suburbs across the Mississippi River — Belleville, O'Fallon, Edwardsville, Alton, Swansea, Collinsville — are served by Ameren Illinois under Illinois regulatory rules. Illinois has the Illinois Shines incentive program, different net metering terms, and different building codes than Missouri. Metro East communities have their own Illinois building departments separate from Missouri AHJs.

STL Market

St. Louis — Healthcare, Biotech, and Logistics Solar Market

St. Louis is home to BJC Healthcare, Mercy Health, SSM Health, and Washington University Medical Center — one of the largest healthcare concentrations in the Midwest. Monsanto/Bayer's agriculture biotech presence and Boeing's manufacturing operations create additional commercial solar demand. The St. Louis County suburban ring — Chesterfield, Wildwood, Ballwin — creates strong residential solar pipeline.

AHJ Solar Permit Design St. Louis

St. Louis and All Surrounding Jurisdictions — Ameren Missouri Interconnection Formatted.

We cover St. Louis City, St. Louis County, and Metro East. Ameren MO or IL confirmed per address.

Jurisdiction	Utility	Permit Type	Key Notes	Review Time
St. Louis City	Ameren Missouri	Bldg + Elec	St. Louis City Building Division · Independent city · 3–5 week review	3–5 weeks
St. Louis County (unincorp.)	Ameren Missouri	County Bldg + Elec	St. Louis County Building · Unincorporated county areas	2–4 weeks
Clayton / Kirkwood	Ameren Missouri	Bldg + Elec	Own city building depts · St. Louis County incorporated cities	2–3 weeks
Chesterfield / Ballwin	Ameren Missouri	Bldg + Elec	Own city building depts · W. St. Louis County · Growing market	2–3 weeks
Webster Groves / Ladue	Ameren Missouri	Bldg + Elec	Own city building depts · Historic inner-ring suburbs	2–3 weeks
Belleville / O'Fallon (IL)	Ameren Illinois	Bldg + Elec	IL building depts · Metro East · IL rules · Confirm utility	2–4 weeks
Edwardsville / Alton (IL)	Ameren Illinois	Bldg + Elec	IL building depts · Northern Metro East · Madison County IL	2–4 weeks

References: Ameren Missouri Solar · St. Louis City Building

What You Get

Solar Permit Package St. Louis — St. Louis Solar Permit Plan Sets. Ameren Missouri Ready.

Cover Sheet — St. Louis PV Permit Plans

NEC 2020 · IBC/IRC 2018 (MO) · St. Louis AHJ · Ameren Missouri utility

Site Plan

Meter and Ameren Missouri interconnection access · ASCE 7 local wind values · Applicable wind zone

Roof Layout

St. Louis rooftop conditions · Array diagram · Pitch, azimuth, setbacks · IFC fire access paths

Single-Line Diagram

NEC 2020 §690.12 rapid shutdown · Battery (Article 706) where included · Ameren Missouri bidirectional meter

Structural Calculations

IBC/IRC 2018 (MO) · ASCE 7 local wind loads · Gravity and lateral loads · PE stamp for commercial

Rapid Shutdown + Labels

NEC 2020 §690.12 · Battery shutdown interface (Article 706)

Equipment Datasheets + Ameren Missouri Interconnection Package

UL-listed module, inverter, racking, and battery datasheets · Ameren Missouri interconnection application · State solar incentive notes

St. Louis Plan Set — 24 Hours.

Ameren Missouri Interconnection · NEC 2020 · All St. Louis AHJs

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How It Works

Three Steps. 24 Hours. St. Louis AHJ Ready.

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Submit the Project

Share address, specs, and design. We confirm the AHJ, Ameren Missouri interconnection, and NEC 2020 format.

5 minutes

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We Build the Plan Set

NEC 2020, IBC/IRC 2018 (MO). St. Louis AHJ formatted. Ameren Missouri interconnection package. Battery where included.

24–48 hours

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Submit Permit + Interconnection

Submit St. Louis City or county building permit and Ameren Missouri interconnection simultaneously. Ameren MO interconnection: 4–8 weeks. Free revisions for any AHJ correction.

Free revisions

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The Permit Design Commitment

Solar permit services in St. Louis — what every installer and EPC gets.

✓AHJ confirmed per address before we build

✓Ameren Missouri interconnection package included

✓24–48 hour delivery on standard residential projects

✓NEC 2020 formatted for MO — not California NEC 2026

✓Free revisions for any AHJ correction on our design

Start Free Trial →

First plan set free.
Licensed installers & EPCs only.

FAQ

Questions St. Louis Installers Ask Us

Ameren Missouri (AmerenMO) serves St. Louis City, St. Louis County, and most of Missouri. Missouri law requires Ameren Missouri to offer net metering for residential solar at the retail rate. Ameren Illinois serves the Illinois side of the metro (Metro East). We confirm utility and state side per address before building.

St. Louis City and St. Louis County are completely separate jurisdictions in Missouri — St. Louis City is an independent city not part of St. Louis County. St. Louis City has its own building department. St. Louis County has its own building department for unincorporated areas, while incorporated county cities (Clayton, Kirkwood, Webster Groves, etc.) have their own departments. Routing to the wrong one results in rejection.

Missouri property tax exemption for solar energy systems. Ameren Missouri net metering at full retail rate. Federal 25D residential credit expired December 31, 2025. Missouri has no state solar income tax credit in 2026.

NEC 2020 under Missouri state adoption.

Missouri has no statewide PE stamp requirement for standard residential rooftop solar. St. Louis City and surrounding county municipalities do not typically require a PE stamp for standard residential installations. Commercial projects require PE-stamped structural drawings.

Yes — Metro East (Belleville, O'Fallon, Edwardsville, Alton) is Illinois territory served by Ameren Illinois. Illinois and Missouri have different net metering rules and different AHJs. We confirm the state side and utility per address for every St. Louis metro project.

Most St. Louis residential plan sets ship in 24 to 48 hours. Battery same day. Commercial: 3 to 5 business days. Rush available.

Nearby Cities

🏙️ Kansas City 🌆 Chicago 🎵 Nashville 📍 Missouri →

Our Services

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Reviewed by the Permit Design Engineering Team — Licensed PE Ameren Missouri (AmerenMO) retail net metering (required by MO law) confirmed. St. Louis City vs St. Louis County independent jurisdictions confirmed from Missouri law. Metro East (Ameren Illinois, IL building codes) confirmed. NEC 2020 MO and IL adoption confirmed. MO property tax exemption for solar confirmed. Federal 25D expiration confirmed. Last reviewed July 2026.

NEC 2020Ameren Missouri Net MeteringSt. Louis City vs CountyMetro East IllinoisSt. Louis Solar Drafting ServicesSt. Louis Solar CAD ServicesJuly 2026

St. Louis Solar Permit Design.
Ameren Missouri Net Metering. City ≠ County AHJ · Metro East IL Side Too.

St. Louis City and St. Louis County Are Completely Separate Jurisdictions. Metro East Is Illinois. Ameren Missouri and Ameren Illinois Are Different Companies. Confirm Per Address Before You Build.

City vs County AHJ Confusion. Metro East IL Side Missed. Ameren MO vs IL Mix-Up.

Ameren Missouri Interconnection. NEC 2020. All St. Louis AHJs.

Four Things That Define Solar in St. Louis.

St. Louis and All Surrounding Jurisdictions — Ameren Missouri Interconnection Formatted.

Solar Permit Package St. Louis — St. Louis Solar Permit Plan Sets. Ameren Missouri Ready.

St. Louis Plan Set — 24 Hours.

Three Steps. 24 Hours. St. Louis AHJ Ready.

Questions St. Louis Installers Ask Us

St. Louis Plan Sets — 24 Hours.

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St. Louis Solar Permit Design.Ameren Missouri Net Metering. City ≠ County AHJ · Metro East IL Side Too.

St. Louis City and St. Louis County Are Completely Separate Jurisdictions. Metro East Is Illinois. Ameren Missouri and Ameren Illinois Are Different Companies. Confirm Per Address Before You Build.

City vs County AHJ Confusion. Metro East IL Side Missed. Ameren MO vs IL Mix-Up.

Ameren Missouri Interconnection. NEC 2020. All St. Louis AHJs.

Four Things That Define Solar in St. Louis.

St. Louis and All Surrounding Jurisdictions — Ameren Missouri Interconnection Formatted.

Solar Permit Package St. Louis — St. Louis Solar Permit Plan Sets. Ameren Missouri Ready.

St. Louis Plan Set — 24 Hours.

Three Steps. 24 Hours. St. Louis AHJ Ready.

Questions St. Louis Installers Ask Us

St. Louis Plan Sets — 24 Hours.

St. Louis Solar Permit Design.
Ameren Missouri Net Metering. City ≠ County AHJ · Metro East IL Side Too.