Quick answer
Electrical bonding connects conductive parts of a solar PV installation to maintain electrical continuity and support fault protection. Its requirements depend on the equipment and locally adopted electrical rules.
What Is Electrical Bonding?
Answer: Electrical bonding joins conductive parts so they maintain electrical continuity and support the installation’s protective measures. In solar PV, this can include metal module frames, mounting rails, enclosures and raceways. Bonding helps limit dangerous voltage differences and provides part of a fault-current path; the required connections and protective devices depend on the equipment, electrical system and locally adopted rules.
A bolted mechanical connection is not automatically an approved electrical bond. Paint, anodizing, corrosion, incompatible hardware or a loose connection can interrupt the intended conductive path. The design must identify how required metal parts connect, including across rail splices and between separate array sections.
Bonding, Grounding and Earthing: What Is the Difference?
| Term | Meaning in this context | Important distinction |
|---|---|---|
| Bonding | Conductive connections between parts that need electrical continuity | Joining frames or rails does not by itself establish the complete protective system. |
| Equipment grounding | Connections that incorporate exposed conductive equipment into the protective fault-current path; often described using an equipment grounding conductor (EGC) in U.S. practice | Grounding is not limited to inserting a rod into soil. |
| Grounding electrode connection | Connection to an electrode in contact with earth | The electrode connection and equipment fault-current path have different roles. |
| Protective earthing | Terminology used in IEC-based installations for protective connections, including PE conductors | The actual fault path and protection depend on the earthing arrangement, such as TT, TN or IT. |
In a system with a metallic fault-return path, a fault from a live conductor to a bonded enclosure can return current toward the supply through protective connections. Do not picture fault current simply disappearing into the ground. Conversely, do not apply that description indiscriminately to every electrical system: TT installations use a different arrangement, including earth electrodes and residual-current protection. Schneider Electric’s earthing-scheme guide explains these differences.
Bonding reduces risk; it does not guarantee that every accessible part remains at exactly the same potential during a fault or that touching equipment is safe. It also does not replace insulation, required protective devices or safe isolation procedures. See equipment grounding for the related term.
Where Bonding Matters in a Solar Array
Module frames and mounting rails. An approved mounting assembly may use integrated bonding clamps, specified washers or separate conductors and terminals. The manufacturer identifies which connections provide electrical continuity and which module models or frame types are covered.
Splices and separate sections. Some approved rail splices provide bonding; other arrangements need a specified jumper or another connection. A structural splice, expansion joint or gap should not be assumed to carry fault current without checking the applicable instructions.
Enclosures, raceways and other equipment. Their protective connections follow the equipment instructions and applicable electrical rules. Whether a metal raceway can serve as a protective conductor depends on its type, fittings and installation conditions. A PV mounting-system certification does not establish that the entire building wiring arrangement is acceptable.
The racking system therefore has both a structural role and, where designed for it, a role in the electrical bonding path.
What UL 2703 Does—and Does Not—Tell You
UL 2703 covers PV mounting systems and associated mounting, retention and grounding/bonding devices. Its published scope refers to specific module manufacturer/model designations. Certification is not permission to interchange any clamp, washer, lug, module and rail that look similar.
For a proposed assembly, record:
- The mounting system and exact bonding component part numbers.
- The applicable module compatibility information and certification scope.
- The installation-manual revision and specified attachment locations.
- Permitted conductor materials, terminal ranges and environmental conditions.
- The manufacturer’s torque, reuse and maintenance instructions.
Use the instructions for the actual equipment rather than a generic torque figure or a rule that every attachment needs the same washer. For example, IronRidge’s hardware page distinguishes grounding lugs, rail attachment bonding hardware and module-level electronics hardware. Those are manufacturer-specific components, not interchangeable categories of universal hardware.
An ordinary serrated washer is not evidence that an assembly meets its bonding requirements. Nor should installers scrape coatings, drill a frame or substitute a lug unless the applicable instructions permit that method. Product warranty terms must be checked separately; this glossary cannot establish coverage.
Bonding Is Only Part of Fault Protection
A protective path must remain suitable for its intended duty. OSHA’s U.S. workplace wiring design and protection rule, for example, addresses a permanent, continuous and effective grounding path. Its workplace requirements are not a substitute for reviewing the locally adopted building electrical code.
Do not assume a PV fault will always trip an ordinary breaker immediately. The protective response depends on the circuit and equipment, including applicable ground-fault detection, insulation monitoring and interruption functions. SMA’s ground-fault instructions for the specified inverter family warn that parts of a faulted PV system may remain live. That warning is incompatible with promising customers that bonding makes an array safe to touch.
Conductor sizing also depends on the applicable circuit rules, protective scheme, equipment and adopted code edition. A single wire-size example is not a safe specification for all PV installations. In U.S. projects, review the relevant grounding and bonding provisions together with NEC Article 690, local amendments and manufacturer requirements. IEC-based projects require their own national rules and system-earthing assessment.
Design and Inspection Documentation
The useful output is a traceable bonding arrangement, not a generic note saying “ground all equipment.” A designer should identify the path from the required frames and mounting components into the installation’s protective system, show how gaps or splices are addressed and reference the equipment instructions used.
Installation records can include component identification, permitted connections, required torque verification and photographs before connections become obscured. Keep substitutions and later module replacements in the record: changing a module or clamp can change the approved assembly.
A qualified person should perform the applicable inspection and commissioning checks using suitable instruments, procedures and acceptance criteria. A continuity beep alone does not establish adequate fault-current capacity, correct hardware installation or safe operation. Testing must account for PV electrical hazards and the manufacturer’s isolation instructions.
For a software evaluation, bring the mounting manual and project documentation to a SurgePV demo and ask which design and documentation steps the available workflow supports. Software output still requires the project’s electrical and equipment review.
Frequently Asked Questions
Does bonding mean connecting solar panels to a ground rod?
No. Bonding establishes required conductive connections between parts. An earth electrode connection is a separate element of the protective arrangement. The complete design depends on the supply system, PV equipment and local rules.
Can the mounting rails bond the module frames?
They can form part of an approved integrated bonding system when the exact module, rail and hardware combination is covered and installed as instructed. Mechanical contact alone is not sufficient evidence.
Does each module need a separate grounding wire?
There is no universal answer. Approved integrated bonding systems and separately wired arrangements differ. Follow the applicable certification, equipment instructions and locally adopted electrical requirements rather than adding or omitting a conductor by rule of thumb.
Is a continuity test enough to approve the bonding?
No. Continuity is one possible check within a wider inspection and commissioning process. Component suitability, installation conditions, connections, protective devices and applicable test acceptance criteria must also be assessed.
Related Glossary Terms
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