2026 NEC Changes for Solar and Energy Storage Installers
The 2026 NEC solar changes don't rewrite PV design. They do change how you round calculations, where you place equipment on supply-side connections, and which code sections appear on your permit plans.
This guide breaks down the 2026 NEC changes that matter most for solar and battery work. You'll find NEC 2026 solar updates in Article 690, the return of supply-side conductor limits in 705.11, and 2026 NEC energy storage changes that move battery backup sizing toward Article 702.
We also cover renumbered articles that affect load calculations and power control systems. If your projects still fall under the previous cycle, our 2023 NEC solar code guide covers those requirements.
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2026 NEC vs 2023 NEC: Solar and Storage Changes at a Glance
Most 2026 NEC Article 690 changes are clarifications rather than major rule changes, according to Ryan Mayfield's 2026 NEC overview for Solar Builder. Mayfield served on the code-making panel responsible for Article 706.
The bigger shifts are in battery backup sizing, supply-side connections, and article numbering. Here's how the 2026 NEC compares with the 2023 edition for solar and storage work.
Topic | 2023 NEC | 2026 NEC | What It Means for Installers |
Load calculations | Article 220 | Article 120 | Update templates, standard notes, and calculation references |
Energy management | Article 750 | Article 130, with separate treatment for power control | Check EMS and PCS terminology and listings |
Rounding PV calculations | No PV-specific rule | 690.4(G) drops fractions below 0.5 | Round final results only after correction factors |
Engineered voltage and current calculations | Systems over 100 kW AC | Any system size | Smaller projects can use stamped engineering calculations |
Maximum PV circuit current | Standard calculation methods | New method using module manufacturer instructions | Helpful for bifacial modules when guidance exists |
PV and ESS disconnects | Requirements written in 690.13 and 706.15 | Both point to 705.20 | Largely the same in practice; update references |
Battery backup sizing | 706.16 and the Article 710 approach | 706.16 deleted; most backup ESS follow 702.4 | Review how you size and document backup capacity |
Supply-side conductor length | No length limits | 705.11(C)(1) limits return | Measure conductor routing before locating the OCPD |
When Does the 2026 NEC Apply to Solar and Battery Projects?
The NEC is a model code, so it only becomes enforceable once a state or local jurisdiction adopts it. NFPA publishes the National Electrical Code (NFPA 70) every three years, and the 2026 edition was released in fall 2025.
Adoption usually lags publication by one to three years. Texas, for example, adopted the 2026 NEC statewide effective September 1, 2026. California's current electrical code, effective January 1, 2026, is still based on the 2023 NEC.
Because editions and amendments vary, check a current tracker such as the IAEI NEC adoption map or Mike Holt's NEC adoption list. Then confirm the details with the AHJ before you design.
Before starting a design, confirm:
☐ Which NEC edition the AHJ enforces
☐ Any state or local amendments to Articles 690, 702, 705, or 706
☐ How the AHJ handles projects submitted before and after the effective date
☐ Whether utility interconnection requirements reference a specific code edition
NEC 2026 Article 690 Changes for Solar PV Systems
The 2026 NEC Article 690 updates focus on calculations and disconnect references. Four changes are worth building into your design workflow.
New 690.4(G) Rounding Rule for PV Calculations
Installers have long asked how to handle fractions of an ampere or volt in PV calculations. New 690.4(G) answers it: fractions less than 0.5 are dropped, and results are rounded to the nearest whole number.
The order of operations matters. Apply all correction factors and conditions of use first, then round the final result.
A calculated maximum circuit current of 13.4 A becomes 13 A.
Rounding happens once, at the end, not at each step of the calculation.
Update spreadsheets and design software so they don't round intermediate values.
Engineered Voltage and Current Calculations Now Apply to Any System Size
Sections 690.7(A)(3) and 690.8(A)(1)(a)(3) allow a licensed electrical engineer to calculate maximum PV voltage and current using a documented, industry-standard method. Before 2026, this path only applied to systems with a generating capacity over 100 kW AC.
The 2026 NEC removed that size threshold, so residential and small commercial projects can now use engineered calculations. This can matter for cold-climate string sizing, where table-based voltage corrections may be more conservative than a site-specific calculation.
When a project relies on these engineered methods, a licensed professional electrical engineer must prepare the calculations. State engineering rules and the AHJ determine sealing and submittal requirements, and solar PE stamping services can cover both.
690.8 Adds a Manufacturer-Based Current Method for Bifacial Modules
New 690.8(A)(1)(a)(2) allows maximum circuit current to be calculated using instructions included with the listed PV module. The method applies to any module, but it's especially useful for bifacial modules.
Estimating bifacial gain has been difficult because rear-side current depends on albedo, mounting height, and row spacing. Bifacial solar panel installation requirements already call for careful current calculations, and manufacturer guidance gives designers a code-recognized path.
Ask the module manufacturer whether its instructions include current calculation guidance.
Include that documentation in the permit submittal.
If no instructions exist, use one of the other 690.8 methods.
PV Disconnect Requirements Now Reference 705.20
Section 690.13 now directs installers to 705.20, which covers disconnecting means for power production sources. In practice, the requirements are largely the same as the 2023 text, with locking requirements referencing 110.25.
Article 706 follows the same pattern, with 706.15 also pointing to 705.20. The result is a more consistent set of disconnect rules across PV, storage, and other power sources.
705.11 Brings Back Conductor-Length Limits for Supply-Side Solar Connections
The 2026 NEC reinstates conductor-length limits for supply-side connections made inside a building. These limits appeared in the 2020 NEC, were removed in 2023, and now return in 705.11(C)(1).
The limits keep unprotected conductors inside buildings short, which reduces the risk from a faulted conductor. For many installers, this is the change most likely to alter an actual equipment layout.
How Long Can Supply-Side Conductors Be Under the 2026 NEC?
The 2026 limits match the 2020 NEC distances. The overcurrent device must be within 10 feet of conductor length in dwelling units and 16.5 feet of conductor length in other buildings.
These distances measure the conductor itself, not the straight-line distance between equipment. Bends, terminations, and routing all count, so the OCPD usually ends up physically closer than the listed length. IAEI's explanation of supply-side PV system connections walks through how these limits worked under 2020.
For certain non-dwelling installations with services up to 1,000 V AC, 705.11(C)(1) also provides an engineered pathway. It allows up to 66 feet of conductor length when cable limiters are installed within 16.5 feet of the point of connection, under engineering supervision.
Check 705.11(C) and any local amendments before finalizing a layout.
2023 vs 2026 Supply-Side Design Comparison
Good designers planned routing and OCPD locations under the 2023 NEC too. The difference in 2026 is that conductor length now directly constrains where the OCPD can go.
Design Question | 2023 NEC | 2026 NEC |
Indoor conductor length | No specific 705.11 length limit | Must satisfy 705.11(C) |
OCPD location | Set by applicable equipment and code requirements | Also constrained by actual conductor length |
Conductor routing | Coordinated with equipment layout | Measured before finalizing the OCPD location |
Plan set documentation | Show the connection and OCPD | Show the connection, routing assumptions, and a compliant OCPD location |
Supply-Side Layout Checklist
Use this checklist when reviewing supply-side designs under the 2026 NEC.
☐ Confirm whether the connection is made inside or outside the building
☐ Measure actual conductor routing length, including bends and terminations
☐ Verify the OCPD and disconnect location against the 705.11(C)(1) limit
☐ Recheck layouts built on 2023-era templates
☐ Confirm any alternative pathway applies to the building's occupancy type
2026 NEC Energy Storage Changes: Battery Backup Sizing Under Articles 702 and 706
The biggest 2026 NEC battery storage change affects how backup capacity is sized. Section 706.16 was deleted, and most interconnected ESS used for backup now follow the optional standby system rules in Article 702.
That shift changes the code path for sizing, controlling, and documenting backed-up loads. Here's what it means for solar plus storage designs.
Why Battery Backup Sizing Moves Toward Article 702
Under the 2023 NEC, 706.16 sent designers to the Article 710 rules for stand-alone systems. Article 710 was written for systems with no utility connection, which doesn't match most grid-tied battery installations.
For typical grid-connected ESS used to supply backup loads, the 2026 NEC generally directs designers to the optional standby system requirements in Article 702. Capacity and rating now run through 702.4, the same framework used for other optional standby power sources.
How 702.4 Sizing Options Work
Section 702.4 gives designers three ways to show that a backup system has adequate capacity and rating for the loads it supplies. All three options are available to ESS.
Sizing Approach | Basic Approach | Typical Application |
Full load | Size the system to supply the full load connected to it | Whole-home or full-panel backup |
Managed load | Size for the maximum load that can be connected when an approved load management system controls the connected load | Selective or managed backup |
Listed PCS pathway | For qualifying inverter-based systems, a listed PCS prevents automatically reconnecting loads from overloading the backup source | One- and two-family dwellings only |
The third option is new for 2026 and applies only to one- and two-family dwellings. It's covered in the next section.
The New PCS Option for One- and Two-Family Dwellings
The new 702.4 option lets inverter-based backup systems in one- and two-family dwellings use a listed power control system (PCS). The PCS prevents loads that automatically reconnect during an outage from overloading the backup system.
UL 3141 is the primary safety standard used to evaluate power control systems for this application. Manufacturers increasingly offer inverter-based systems with integrated PCS functionality evaluated to UL 3141.
For permit plans, expect to document:
The multimode inverter and its listing
PCS functionality and settings
Which loads are backed up and which are controlled
The 702.4 option used to show adequate capacity
These details sit alongside the NFPA 855 and Article 706 items covered in our guide to solar battery storage permits.
Designing solar plus storage under the 2026 NEC? GreenLancer prepares solar plus storage plan sets that document backup sizing, PCS settings, and equipment listings for AHJ review.
Article 130 Separates Energy Management From Power Control
The 2026 NEC moved energy management systems from Article 750 to Article 130. The new article also draws a clearer line between general energy management and power control used to prevent overloads.
That distinction matters for solar plus storage, service-upgrade avoidance, and electrification projects on existing services.
EMS vs PCS: What's the Difference?
The two systems can look similar on a jobsite, but they do different jobs.
Energy management system (EMS): Manages energy use or operating strategy, such as scheduling loads or shifting battery charging.
Power control system (PCS): Controls sources, loads, or both to keep current or power within set limits, so conductors and equipment aren't overloaded.
UL describes a PCS as a control system that electronically limits current or power to mitigate overloads, as explained in its power control systems white paper.
Where UL 3141 Fits in Solar and Storage Design
UL lists EMS equipment to UL 916 or UL 60730-1 and lists PCS to UL 3141, according to UL's summary of Article 130 energy management systems. When a system performs overload control, expect the AHJ to look for a PCS listing.
One key PCS application is avoiding service upgrades by keeping feeder and service conductors within their ratings. Mayfield Renewables explains this use case in its guide to UL 3141 and power control systems.
Section 705.13 is also refocused on PCS in 2026, with informational notes referencing UL 3141 and UL 1741. Designers using PCS instead of the busbar math in the 120% rule for solar should confirm the product's PCS listing through UL 3141 certification records.
Article 220 Moved to Article 120: What Solar Installers Need to Update
Branch-circuit, feeder, and service load calculations moved from Article 220 to new Article 120. Most of Article 120 isn't specific to solar, but it often decides whether PV, storage, or a PCS fits on an existing service.
For solar installers, three updates matter most:
Template references: Plan templates and standard notes that cite Article 220 need updating for 2026 NEC projects.
Service calculations: Load calculations supporting a main panel upgrade or service evaluation now cite Article 120.
PCS-controlled loads: Section 120.7 establishes how a compliant PCS can be incorporated into branch-circuit, feeder, or service load calculations, based on the PCS monitoring and control configuration.
Other Article 120 changes can affect service calculations too. For dwelling feeder and service load calculations, the general lighting and general-use receptacle load drops from 3 VA to 2 VA per square foot. Branch-circuit calculations still use 3 VA per square foot.
What Should Solar Installers Change for the 2026 NEC?
Solar installers working under the 2026 NEC should update calculation sheets and plan templates, verify supply-side conductor routing under 705.11, and document manufacturer-supported current calculations for bifacial modules. They should also replace Article 220 and 750 references with Articles 120 and 130, and review battery backup sizing under Article 702.
How the 2026 NEC Changes Solar and Storage Permit Plans
Most 2026 NEC solar changes show up on specific sheets of a permit plan set. Here's where plan reviewers are likely to look.
PV Calculation Sheets
Calculation sheets carry the most direct Article 690 changes.
Apply 690.4(G) rounding only to final results
Note when voltage or current calculations use the engineered method in 690.7 or 690.8
Attach manufacturer current instructions for bifacial modules
One-Line Diagrams
One-line diagrams need updated references and clear equipment locations.
Show supply-side OCPD locations that meet 705.11(C)(1)
Identify PCS functionality and settings
Replace Article 220 and 750 references with Articles 120 and 130
Confirm labeling and initiation details using our solar rapid shutdown requirements guide
Battery and Backup Plans
Battery plans now need to show how the design meets Article 702.
State which 702.4 option the design uses
List backed-up loads and controlled loads separately
Include multimode inverter, ESS, and PCS listings
GreenLancer prepares solar and storage plan sets and PE-stamped solar engineering around the NEC edition and amendments enforced by the project's AHJ. That includes updated calculations, one-line references, ESS backup details, and PCS documentation.
2026 NEC Readiness Checklist for Solar Installers
Use this checklist to prepare your team, templates, and submittals for 2026 NEC projects.
☐ Confirm the adopted NEC edition and local amendments with each AHJ
☐ Update calculation sheets for 690.4(G) rounding
☐ Replace Article 220 and 750 references with Articles 120 and 130
☐ Recheck supply-side conductor routing against 705.11(C)(1)
☐ Collect manufacturer current instructions for bifacial modules
☐ Document PCS settings, controlled loads, and listings
☐ Size battery backup systems under 702.4
☐ Get PE calculations when the design relies on engineered methods
Get 2026 NEC-Ready Plan Sets With GreenLancer
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FAQs: 2026 NEC Solar Changes
What changed in the 2026 NEC for solar installations?
The main 2026 NEC solar changes include a new rounding rule in 690.4(G), engineered voltage and current calculations for any system size, and a manufacturer-based current method useful for bifacial modules. Supply-side conductor-length limits also return in 705.11, and load calculations moved to Article 120.
When does the 2026 NEC apply to solar projects?
The 2026 NEC applies only after a state or local jurisdiction adopts it. Adoption typically lags publication by one to three years, and many states add amendments. Confirm the enforced edition with the AHJ before designing a project.
What changed for battery storage in the 2026 NEC?
Section 706.16 was deleted, and most interconnected battery systems used for backup now follow the optional standby rules in Article 702. Backup capacity is sized under 702.4, which includes a new option for one- and two-family dwellings using a listed power control system.
Did NEC Article 220 become Article 120?
Yes. In the 2026 NEC, branch-circuit, feeder, and service load calculations moved from Article 220 to Article 120. Plan templates and standard notes that cite Article 220 need updating for projects reviewed under the 2026 edition.
Can smaller solar systems use engineered voltage and current calculations under the 2026 NEC?
Yes. Sections 690.7(A)(3) and 690.8(A)(1)(a)(3) previously limited engineered calculations to systems over 100 kW AC. The 2026 NEC removed that threshold, so a licensed electrical engineer can use a documented, industry-standard method on systems of any size.
How does the 2026 NEC address bifacial module current?
New 690.8(A)(1)(a)(2) allows maximum circuit current to be calculated using instructions included with the listed module. This is especially useful for bifacial modules, where rear-side gain varies with albedo and mounting height, as long as the manufacturer provides that guidance.
What changed for supply-side solar connections under 705.11?
The 2026 NEC reinstates conductor-length limits for supply-side connections made inside a building, which were removed in 2023. The overcurrent device must be within 10 feet of conductor length in dwelling units and 16.5 feet in other buildings, measured along the conductor rather than in a straight line.
What is the difference between an EMS and a PCS under the 2026 NEC?
An energy management system manages energy use or operating strategy. A power control system limits current or power from sources, loads, or both to prevent overloads on conductors and equipment. In the 2026 NEC, both are addressed in Article 130, and PCS products are evaluated to UL 3141.
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