The intent of this brief is to provide code-related information about photovoltaic systems to help ensure that what is proposed regarding the photovoltaic ‘product’ itself, including accessories such as inverters and controls, as well as their individual and collective installation can be verified as being in compliance with safety-related codes and standards for residential construction. Providing consistent information to document compliance with codes and standards to all relevant parties responsible for verifying compliance with those codes and standards (e.g., code officials, builders, contractors, designers, utilities, fire officials, etc.) is expected to result in increased compliance and more timely, less challenging and more uniform plan review and field inspections.
Photovoltaic systems can provide power for a single use or building, be connected to the utility grid, or could be a hybrid of the two. They can be mounted on building roofs or walls, integrated as an actual component of roof or wall construction, or simply mounted at grade or elevated above grade on a supporting framework. Codes that are relevant to such systems when installed on, as part of, or adjacent to a home include the National Electric Code (NEC), the structural sections of the International Residential Code (IRC), and the renewable-energy sections of the International Energy Conservation Code (IECC) as well as a number of safety standards that area referenced in these documents and address portions of the photovoltaic system (e.g. IEEE or Underwriters Laboratory [UL standards] as referenced in these documents and applicable to the photovoltaic system and its components). The installation of photovoltaic panels on a building roof or integral with a building roof also raises other code issues (e.g., roof loading, wind loading, fire ratings, weather tightness, mounting systems, roof penetrations, etc.), which may also be relevant for systems mounted on or integral to a wall.
An increased number of photovoltaic systems are being deployed to help meet household energy needs. For a home to qualify as a U.S. Department of Energy Zero Energy Ready Home, it must be constructed, at a minimum, as “solar energy ready.”  Any initiative focused on the application and use of wind, photovoltaic, or other renewable resources will likely require the installation of a system to store excess energy for subsequent use (refer to the referenced Code Brief on Design and Installation of Electrical Energy Storage Systems for additional information and the Database of State Incentives for Renewables and Efficiency at http://www.dsireusa.org/. Beyond this DOE initiative, some builders and homeowners choose to install photovoltaic systems—whether they are participating in a program or not—simply to have power from non-utility sources to reduce their monthly electric bills as well as to enhance the value and appeal of the home. This brief provides further clarification and resources to assist with designing, constructing, and installing these type of systems and/or system components and verifying that they are safe and meet code.
The following sections list the applicable code and standard requirements and details helpful for Plan Review. The Field Inspection section then provides details for inspecting “… photovoltaic systems.” For resources on technical validation, best practices, and measure guidelines, refer to the Technical Validation/Reference Materials section of this brief.
The lists and provisions provided below in each section are intended to target the primary code sections and provisions. There may be other references, code sections, standards, testing methods, etc., that affect the technology or other assemblies or functions of the building.
 Institute of Electronics and Electrical Engineers, Standards Association, https://standards.ieee.org/
 DOE Solar Energy Ready Program Requirements, http://www.energy.gov/sites/prod/files/2014/04/f15/doe_zero_energy_ready_home_requirements_rev04.pdf
 The intent of solar energy ready requirements is to provide a penetration free and shade free portion of the roof, called the solar zone. This helps ensure future installation of a solar energy system is not precluded by the original design and layout of the building and its associated equipment.
This section provides details in the 2015 IRC .
2015 IRC, Section R104 Duties and Powers of the Building Official
2015 IECC/IRC, Section R104.1 General. The building official has authority to render interpretations of this code and to adopt policies and procedures in order to clarify the application of its provisions. Such interpretations, policies and procedures shall be in conformance with the intent and purpose of this code.
R102.1/R104.11 Alternative Materials, Design and Method of Construction and Equipment. The provisions of this code are not intended to prevent the installation of any material or prohibit any design or method of construction not specifically prescribed in the 2015 IECC/IRC, provided that any such alternative has been approved. The building official is permitted to approve an alternative material, design, or method of construction where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and the material, method, or work offered is for the purpose intended, not less than the equivalent of that prescribed in the code. Compliance with the specific performance-based provisions of the International Codes is an alternative to the specific requirements of this code.
R104.11.1 Tests. Whenever there is insufficient evidence of compliance with the provisions of this code, or evidence that a material or method does not conform to the requirements of this code, or in order to substantiate claims for alternative materials or methods, the building official has authority to require tests as evidence of compliance to be made at no expense to the jurisdiction. Test methods shall be as specified in this code or by other recognized test standards. In the absence of recognized and accepted test methods, the building official shall approve the testing procedures. Tests shall be performed by an approved agency. Reports of such tests shall be retained by the building official for the period required for retention of public records.
Per the 2015 IECC/IRC, Section R103.3/R106.3 Examination of Documents, the code official/building official must examine or cause to be examined construction documents for code compliance.
Construction Documentation. Review the construction documents for details describing photovoltaic system and/or components construction techniques.
2015 IECC/IRC, Section R103.2/N1101.5 Information on construction documents. Construction documents should include:
- Design, size, and location
- System ratings, testing, and labeling
- Conduit, wiring, and electrical layout design
- Mounting specifications
- Inverter location and listing.
2015 IRC, Section 324 Solar Energy Systems
R324.3 Photovoltaic systems. Photovoltaic systems shall be designed and installed in accordance with Sections R324.3.1 through R324.7.1 and the manufacturers installation instructions. The electrical portion of solar PV systems shall be designed and installed in accordance with NFPA 70.
R324.3.1 Equipment listings. Photovoltaic panels and modules shall be listed and labeled in accordance with UL 1703 or with both UL 61730-1 and UL 61730-2. Inverters shall be listed and labeled in accordance with UL 1741. Systems connected to the utility grid shall use inverters listed for utility interaction. Mounting systems listed and labeled in accordance with UL 2703 shall be installed in accordance with the manufacturers instructions and their listings.
R324.4 Rooftop-mounted photovoltaic systems. Rooftop-mounted photovoltaic panel systems installed on or above the roof covering shall be designed and installed in accordance with this section...
R324.4.1 describes structural requirements including roof load and wind load.
R324.4.2 describes fire classification. R324.4.3 describes roof penetrations.
R324.5 describes building-integrated photovoltaic systems.
R324.6 describes roof access and pathways including setbacks, and emergency escape and rescue openings.
R324.7 describes ground-mounted PV systems.
Per the 2015 IECC, Section R104 Inspections, construction or work for which a permit is required is subject to inspection. Construction or work is to remain accessible and exposed for inspection purposes until approved. Required inspections include footings and the foundation, framing and rough-in work, plumbing rough-in, mechanical rough-in, and final inspection.
Per the 2015 IRC, Section R109 Inspections, for onsite construction, from time to time the building official, upon notification from the permit holder or his agent, can make or cause to be made any necessary inspections. Further details are provided for inspections regarding foundation, plumbing, mechanical, gas and electrical, floodplain, frame and masonry, and final inspection. Any additional inspections are at the discretion of the building official.
This section provides details for inspecting to the specific provisions for design and installation of photovoltaic systems where one or more specific types of inspection called for by the IECC or IRC may be necessary to confirm compliance. To confirm code compliance, the electrical and/or final inspection would be the typical types of inspections performed.
- Confirm the type of photovoltaic system, design, size and location per the approved construction documentation
- Confirm system ratings, testing and labeling
- Confirm electrical design installation and specifications
- Confirm the inverter installation location and listing
- Confirm rooftop-mounting components are installed per manufacturer specifications and approved construction documents.
- Architectural Drawings for Solar Photovoltaic Systems, https://basc.pnnl.gov/resource-guides/architectural-drawings-solar-photovoltaic-systems
- Inverter Meter and Shut-Off Mounting Surface for Solar PV Systems, https://basc.pnnl.gov/resource-guides/inverter-meter-and-shut-mounting-surface-solar-pv-systems
- Solar Plumbing and Wiring Chase, https://basc.pnnl.gov/resource-guides/solar-plumbing-and-wiring-chase
- 70-Amp Dual-Pole Circuit Breaker for PV Systems, https://basc.pnnl.gov/resource-guides/70-amp-dual-pole-circuit-breaker-pv-systems
- Design and Installation of Electrical Energy Storage Systems, https://basc.pnnl.gov/code-compliance/design-and-installation-electrical-energy-storage-systems-code-compliance-brief
- Roof Anchor System for Solar Panels, https://basc.pnnl.gov/resource-guides/roof-anchor-system-solar-panels
- Solar Orientation for Solar Arrays and Panels, https://basc.pnnl.gov/resource-guides/solar-orientation-solar-arrays-and-panels
- Water Managed Existing Roof Penetrations, https://basc.pnnl.gov/resource-guides/water-managed-existing-roof-penetrations
- Wiring Conduit for Solar PV Systems, https://basc.pnnl.gov/resource-guides/wiring-conduit-solar-pv-systems