NEC Section 690.2 was completely removed in the 2023 National Electrical Code. All solar photovoltaic definitions previously housed in Section 690.2 have been relocated to Article 100, which serves as the centralized location for all electrical definitions throughout the NEC.
Key changes to solar PV definitions in the 2023 NEC:
Why this matters: Solar installers, designers, and inspectors must now reference Article 100 instead of Article 690.2 for all photovoltaic terminology. This reorganization aligns with NEC Style Manual requirements and standardizes electrical definitions across all code sections, not just solar-specific articles.
The 2023 National Electrical Code introduced significant structural changes to how solar photovoltaic terminology is organized and standardized. This restructuring represents a fundamental shift in how the electrical industry approaches solar system terminology and code compliance, affecting permit applications, design documentation, labeling requirements, and inspection procedures.
In previous editions of the NEC, Section 690.2 served as the centralized location for all photovoltaic system definitions. Installers, inspectors, and designers could reference this single section to understand the specialized terminology used throughout Article 690. However, the 2023 NEC completely removed this section, relocating all definitions to Article 100.
This change aligns with the NEC Style Manual, which mandates that definitions of terms used throughout the code document should only be located in Article 100. Code-Making Panel 4 implemented this reorganization to eliminate confusion and create consistency across all NEC articles, not just solar-specific sections.
The relocation of photovoltaic definitions from Article 690.2 to Article 100 serves multiple important purposes. First, it standardizes terminology across the entire codebook, ensuring electrical terms apply consistently throughout all NEC sections rather than being isolated to solar installations alone. This universal approach reduces misinterpretation when PV systems interact with other electrical systems covered by different articles.
Second, the consolidation improves code navigation and enforcement. Authority Having Jurisdictions, electrical inspectors, and installation professionals now access all electrical definitions from a single, predictable location. This streamlines the permitting process and inspection procedures while reducing the likelihood of overlooked requirements.
Third, the change reflects industry maturation. As solar installations have become mainstream rather than specialty applications, treating PV terminology the same as other electrical system definitions acknowledges their integration into standard electrical infrastructure.
The 2023 NEC not only relocated existing definitions but also introduced new terms and consolidated others to address longstanding confusion in the industry. Several key definitions emerged from public input provided by the PV Industry Forum, which identified terminology that had caused problems for installers, inspectors, and system designers.
One of the most significant additions is the formal definition of "PV String Circuit," which had never been officially defined in previous code cycles despite widespread industry use of terms like "string," "series string," or "string circuit." The 2023 NEC defines a PV String Circuit as the PV source circuit conductors of one or more series-connected PV modules.
This new definition provides clarity for circuit identification and creates consistency across labeling requirements, wiring specifications, and compliance documentation. The term now appears throughout Article 690, particularly in Section 690.7(A) regarding maximum voltage calculations, replacing the previously used "PV output circuit" terminology.
The code introduced a comprehensive umbrella term: PV DC Circuit, also referenced as PV System DC Circuit. This definition encompasses any DC conductor in PV source circuits, PV string circuits, and PV DC-to-DC converter circuits. This consolidation simplifies circuit classification by grouping previously separate categories under one clear designation.
The definition of PV Source Circuit was expanded in the 2023 revision to include more circuit types. It now encompasses the PV DC circuit conductors between modules in a PV string circuit, and from string circuits or DC combiners to DC combiners, electronic power converters, or a DC PV system disconnecting means. This broader definition absorbed what were previously classified as PV output circuits, eliminating confusion about where source circuits end and output circuits begin.
Several definitions were completely removed from the NEC because the terminology itself was deleted from Article 690. These eliminated terms include:
The removal of these terms reflects the code panel's response to industry feedback indicating that overly precise circuit classifications created more confusion than clarity. The revised approach groups these circuits into broader, more intuitive categories.
A new general definition for "electronic power converter" was added to Article 100, encompassing both inverters and DC-to-DC converters. This term now appears in equipment listings throughout Article 690.4(B), replacing separate references to inverters and DC-to-DC converters individually.
The definition changes directly affect how installers and designers document and implement PV systems. The elimination of separate categories for PV output circuits means that calculations and conductor sizing now reference the expanded PV source circuit definition. This simplification reduces the likelihood of errors in determining where specific requirements apply.
For voltage calculations under Section 690.7, designers must now reference PV string circuits rather than previous terminology. The maximum PV system voltage equals the sum of PV module-rated open-circuit voltages of series-connected modules in the PV string circuit, corrected for the lowest expected ambient temperature using open-circuit voltage temperature coefficients from the module listing or labeling.
The updated terminology also affects conductor sizing requirements in Section 690.8. When multiple PV string circuits connect in parallel and share a single overcurrent device, the ampacity of each conductor must account for the maximum current calculated under 690.8(A)(1)(a), including the rating of the overcurrent device plus the sum of maximum currents from other parallel-connected PV string circuits.
The definition changes necessitated revisions to the informational figures in Section 690.1. Previous editions included separate diagrams (Figures 690.1(a) and 690.1(b)) showing different system configurations. The 2023 NEC consolidated and revised these illustrations to reflect the new terminology, eliminating references to DC-to-DC converter source circuits, DC-to-DC converter output circuits, and PV output circuits.
The updated Figure 690.1 now focuses on core system components and the various circuits within a PV system, using the standardized definitions from Article 100. This visual reference helps installers and inspectors quickly identify components and understand how the new terminology applies to actual system layouts.
For solar installation professionals, the elimination of Section 690.2 requires adjusting reference habits. Rather than looking to Article 690.2 for PV-specific definitions, all terminology now requires consultation of Article 100. This change applies to permit applications, design documentation, and inspection communications.
System designers should update plan sets and technical specifications to reflect the new terminology. References to "PV output circuits" must be replaced with "PV source circuits" or "PV string circuits" as appropriate. Equipment specifications should reference "electronic power converters" rather than separately listing inverters and converters.
Inspectors benefit from the standardized approach because definitions now maintain consistency across all electrical installations, not just PV systems. This uniformity reduces interpretation disputes and creates clearer enforcement standards. However, inspectors must familiarize themselves with the relocated definitions and updated terminology to properly evaluate installations under the 2023 code.
The definition changes affect required labeling throughout Article 690. Rapid shutdown labels under Section 690.12(D) must use terminology consistent with PV string circuits and PV source circuits. Maximum voltage labels under Section 690.7 must reference the highest maximum DC voltage calculated using the string circuit definition.
System identification placards required under Section 690.56 and Article 705.10 should accurately reflect the standardized terminology. Mitigating confusion between old and new code cycles requires clear, consistent use of the 2023 definitions on all system labels and documentation.
The relocation of definitions from Section 690.2 to Article 100 exemplifies the ongoing evolution of the National Electrical Code. As photovoltaic technology advances and installation practices mature, the code adapts to improve clarity, safety, and enforcement consistency. Solar professionals must stay informed about these structural changes to ensure compliant installations that meet both current safety standards and jurisdictional requirements.
Understanding that Section 690.2 no longer exists in the 2023 NEC is crucial for anyone working with photovoltaic systems. All previously included definitions now reside in Article 100, with several terms eliminated entirely and others expanded or newly created. This reorganization standardizes solar terminology across the electrical industry and aligns photovoltaic definitions with the broader NEC structure.
The elimination of NEC Section 690.2 represents more than a simple organizational change. It reflects the electrical industry's recognition that photovoltaic systems have become integral to standard electrical infrastructure rather than specialized standalone installations. By relocating all PV definitions to Article 100, the 2023 NEC ensures consistent terminology application across all electrical work, improves code navigation, and reduces confusion between different system types.
As jurisdictions continue adopting the 2023 NEC, staying current with these definitional changes becomes essential for successful permit acquisition, passing inspections, and delivering compliant solar installations. Solar professionals should thoroughly review Article 100 to understand the complete set of photovoltaic definitions now governing system design, installation, and inspection.
Where can I find solar PV definitions in the 2023 NEC if Section 690.2 was removed?
All solar photovoltaic definitions previously located in Section 690.2 have been relocated to Article 100 in the 2023 NEC. Article 100 serves as the centralized location for all electrical definitions throughout the code. This includes terms like PV String Circuit, PV Source Circuit, PV DC Circuit, and Electronic Power Converter. Installers, designers, and inspectors should now reference Article 100 whenever they need to verify the official definition of any PV-related terminology.
What is a PV String Circuit according to the 2023 NEC?
The 2023 NEC defines a PV String Circuit as the PV source circuit conductors of one or more series-connected PV modules. This is the first code cycle to officially define this term, despite its widespread use in the solar industry for years. The definition now appears in Article 100 and is referenced throughout Article 690, particularly in Section 690.7(A) for maximum voltage calculations. Understanding this definition is crucial for proper circuit identification, labeling, and documentation.
Why did the NEC eliminate the term "PV Output Circuit"?
The term "PV Output Circuit" was eliminated because it caused confusion about where source circuits end and output circuits begin. Industry feedback from the PV Industry Forum indicated that the overly precise circuit classifications created more problems than they solved. The 2023 NEC consolidated this terminology into the expanded definition of PV Source Circuit, which now encompasses what were previously classified as both source and output circuits. This simplification makes circuit classification more intuitive and reduces documentation errors.
Do I need to update my existing solar system documentation to reflect the 2023 NEC definitions?
If designing new systems or submitting permit applications under the 2023 NEC, all documentation must use the updated terminology. References to "PV output circuits" should be replaced with "PV source circuits" or "PV string circuits" as appropriate. Equipment specifications should use "electronic power converters" rather than listing inverters and DC-to-DC converters separately. However, existing installed systems that were permitted under previous code cycles do not require retroactive documentation updates unless modifications are made that trigger new permit requirements.
How does the definition change affect rapid shutdown labeling requirements?
Rapid shutdown labels under Section 690.12(D) must now use terminology consistent with the 2023 definitions. Labels should reference "PV string circuits" and "PV source circuits" rather than outdated terms like "PV output circuits." The wording must accurately reflect which circuits are controlled by the rapid shutdown system. Maximum voltage labels under Section 690.7 must also reference the highest maximum DC voltage calculated using the PV string circuit definition. Using incorrect or outdated terminology on required labels can result in inspection failures and compliance issues.
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