Preparing to Inspect Your First PV System

“I’m starting to see more and more residential solar PV systems in my jurisdiction. Now I’m being asked to inspect my first system. How should I get started?”

Properly installed solar PV systems are safe and designed to last more than 20 years. Code officials play a critical role in ensuring their safe installation. If PV systems are new to you, or you’re getting ready to inspect your first system, you’ll want to understand how these systems work and your role in ensuring that safety regulations and requirements have been followed during the design and installation process.

This resource will introduce you to the components of a typical system, relevant codes and standards, and permitting and inspection guides, and show you where to learn more.

Understanding a Site With a PV System

Solar electric systems are often called PV systems, short for photovoltaic. A PV module turns sunlight into electricity.

One of the unique aspects of a PV system is that it is another source of power, rather than a load. When you have the PV system generating electricity and connected to the utility grid, you’ve got parallel power production. Parallel power production occurs when there is more than one source of power production for a building. The solar PV system operates in parallel with utility-generated electricity.

PV systems create direct current (DC), like a battery. While alternating current (AC) in buildings is familiar, a PV system is likely the first time you have encountered DC electricity. There are product standards, building and electrical codes, and other requirements and regulations that support the safe installation and operating of a PV system.  

While generating electricity from sunlight is a straightforward process, there are several components that are common to most PV systems. Components in a PV system are located in a variety of locations, from the roof to the basement. What should you be looking for and where will you find it?

To begin with, the overall installation should be neat and well documented in the plan submitted as part of the permit application. System documentation should include manufacturer specification sheets and installation instructions. PV technology continues to advance. And that means code officials need to educate themselves on today’s technology and also know where to go for information if something is new or unfamiliar. 

For example, different mounting options for panels (roof- or ground-mounted) mean different requirements govern the installation. The same is true for the system inverter(s). While the function remains the same, the specific system you’re inspecting may have different or unique requirements due to the configuration or components at a specific site.

Learn About Common PV System Components

Below are just a few examples of components and features of PV systems that might be different from what you’re used to seeing during a residential electrical inspection. Familiarize yourself with each as they relate to a PV installation. Even components you already know about can have different requirements when installed as part of a PV system. It’s important to understand applicable codes and regulations along with learning about system components.

PV modules/array

• Verify system voltage and amperage calculations
• Verify module connections have been made according to system design and manufacturer specifications
  • Note: Modules wired in series increase system voltage
  • Note: Modules wired in parallel increase system amperage

Mounting systems and roof penetration

• Modules are attached to the mounting structure according to manufacturer specifications
• Roof penetrations are flashed and sealed according to building code
• Array configuration provides access and pathways for firefighters

Grounding (equipment grounding and system grounding)

• Many components in a PV system are grounded in the same way other electrical equipment is, but grounding of the PV modules is an area to pay attention to
• Many common grounding components are not suitable for outdoor use
• Check for dissimilar metals in contact with one another to prevent galvanic corrosion 

Current carrying conductors

• Listed for the application and the environment
• Array conductors must be secured and supported to prevent damage due to abrasion 
• DC conductors are color-coded properly

Inverter(s)

• Provide conversion of DC from the PV array to AC and allow for connection to the utility grid
• Depending on the type of PV system installed and equipment chosen, there may be one or more inverters installed

Overcurrent protection

• Overcurrent devices on the DC side must be listed for DC use in building applications
  • Note: Automotive, marine or telecom devices must not be used
• Overcurrent protection devices are sized appropriately and take into account module temperature as well as irradiance level

Disconnects

• A system disconnect allows the system to be shut down in case of emergencies
  • The DC disconnect interrupts the flow of power from the PV array
  • The AC disconnect interrupts the flow of power from the inverter
• Equipment disconnects can isolate components for system maintenance
• Note: The modules in the array still produce voltage and current any time there is light

Identify Applicable Codes, Standards, and Regulations

PV installations must comply with all local building, electrical, and fire codes according to the Authority Having Jurisdiction (AHJ). 

PV systems generate electricity when the modules are exposed to natural light. This means that modules and system equipment will be “live” at all times. This can pose a hazard to people performing work on site or emergency responders if they are unfamiliar with PV systems, as there are additional steps that must be taken to ensure they can operate safely around the equipment.

The design, installation, and operation of a PV system requires adherence to building, electrical, and fire codes and product standards. Regulations governing PV systems:

• Provide for the structural integrity of the building and its suitability for installation of a PV system.
• Address electrical safety of the PV system and provide for system disconnection.
• Ensure fire safety and provide safe access for firefighters during emergency situations.

Specifically, the following are applicable to PV Systems:

• International Energy Conservation Code (IECC) 2021: This code contains many sections relating to PV/Solar storage systems and Building Controls and Automation.
• International Building Code (IBC) 2021: This code contains PV/Solar requirements, as they relate to building integrity and design.
• International Residential Code (IRC) 2021: The Residential Code includes all residential solar provisions/regulations.
• International Mechanical Code (IMC) 2021: This code details the design, installation, and equipment necessary to implement solar storage and PV technologies.
• International Fire Code (IFC) 2021: Like NFPA-1 (see below), the IFC has fire safety and protection protocols that cover all distributed energy resource (DER) technologies.
• National Fire Protection Association 70 (NFPA-70) 2020: NFPA-70, or the National Electrical Code, has important information relating to solar, energy storage, and electric vehicle technologies.
• National Fire Protection Association 1 (NFPA-1) 2020: Similar to the IFC, the NFPA-1 is the leading fire safety code across the country. In order to meet code, all DER installations have to abide by NFPA-1 regulations.
• National Fire Protection Association 855 (NFPA-855) 2020: NFPA-855 is the National Energy Storage Standard. This standard contains all regulations and safety protocols related to energy storage systems, a major DER topic within the database.
• National Fire Protection Association 101 (NFPA-101) 2020: NFPA 101 is the National Life Safety Code which contains many labeling, access, and protection requirements related to many DER technologies.

As well as adhering to required codes, the products and equipment used in PV systems must be certified by a Nationally Recognized Testing Laboratory (NRTL). Codes, product standards, and regulations governing the installation of PV systems provide assurance that they can be safely installed and operated.

Learn More

You have taken the first step to get ready for your first PV system inspection. You have a basic idea of the components and what you should find on site. PV systems evolve as technology advances. The following resources will help you to learn more about PV system components and safety and prepare you for your first PV system inspection.

Components of a PV System

• 5-minute video, What Are PV Components? (International Association of Electrical Inspectors [IAEI], September 2021)
• Full webinar: Photovoltaic Systems- Meet the Components (IAEI, September 2021)
• Photovoltaic Systems- The Basics (IAEI webinar, June 2021)
• IAEI On-Demand Digital Education (IAEI)

Relevant Codes and Standards

• Check out this resource from IREC that outlines the codes and standards that are relevant to PV systems.

• National Simplified Residential PV and Energy Storage Permit Guidelines (SolSmart) 
• Current list of NRTLs (OSHA)

Recommended Courses for Code Officials

• Photovoltaic Systems (IAEI 2-part series Sept 2020)
• Complete courses designed for code officials about PV system inspection (IREC)