Solar module rail bonded with grounding conductor

Solar Panel Grounding for DIYers Starts With NEC 690.43

Yes, you need to ground your array: every exposed metal part must be bonded and tied to an equipment grounding conductor under NEC 690.43. Use UL 2703 listed bonding hardware and keep the ground path continuous from the frames to the main grounding point. Microinverters, AC modules and local rules can change the details, so confirm them with the manufacturer and your inspector.

TL;DR:

  • Check UL Product iQ listings because some mounting products qualify only for mechanical loading; confirm bonding coverage for the exact module and rail combination.
  • NEC 250.122 sizes the equipment grounding conductor by overcurrent device rating, while separate DC and AC rules govern the grounding electrode conductor.
  • Confirm local code and inspector requirements first, then torque lugs to specifications and test continuity from the farthest frame to the main bus.
  • On battery backed systems, do not ground a positive or negative DC conductor unless the equipment maker requires it; generator grounding follows separate rules.
  • Use bonding components rated for the frame material and environment, because copper against aluminum can corrode and eventually break electrical continuity.
Gridwiseliving
Plan a More Independent Solar Setup
Gridwise Living offers solar systems for homeowners seeking energy independence, alongside practical solutions for more self-reliant living.
Explore solar solutions

Table of Contents

What do the code and standards require for solar panel grounding?

Several layers of rules shape every grounded array: the National Electrical Code (NEC), the product standard for mounting hardware, and your local authority having jurisdiction (AHJ), which is the permit office or inspector who signs off on the work. Knowing which rule comes from where makes the later steps easier to defend at inspection.

The core requirement sits in NEC 690.43. All exposed, non-current-carrying metal parts of a PV array, including module frames, mounting structures and enclosures, must be bonded and connected to an equipment grounding conductor (EGC). That gives fault current a safe route back to the source, so a breaker trips instead of a rail staying energized.

Exposed metal parts of a PV array must be bonded to an EGC regardless of system voltage. A small array gets the same bonding treatment as a large grid-tied one.

It also helps to separate two ideas that people mix up:

  • Equipment grounding bonds non-current-carrying metal, such as frames, rails and enclosures, so a fault has a low-resistance path.
  • System grounding ties a current-carrying conductor, such as a neutral, to earth. Industry guidance on system versus equipment grounding treats both as necessary, but they do different jobs.
  • NEC Article 250 supplies the general grounding and bonding rules and the conductor sizing tables that Article 690 points back to.
  • UL 2703 is the standard for mounting systems and bonding devices, which we cover next.

UL 2703 matters because of what it certifies. Mounting systems and bonding devices such as clamps and lugs must be listed, labeled and identified for bonding the specific modules and mounting systems they are used with. The standard covers both mechanical loading and electrical grounding capability.

That is why a part’s listing deserves a real check. UL’s own code guidance explains that some products are listed for mechanical loading only, while others are listed for bonding too, so verifying the listing on UL Product iQ is part of the job. Section 5 shows how.

Which parts of your array must be bonded and grounded?

Think of the array as one connected metal object. Anything a person could touch that is made of conductive metal needs a path to the grounding system. A missed rail splice or an unbonded combiner enclosure is one of the more common reasons an array fails inspection.

Work through these items in order:

  1. Module frames. Each aluminum frame must be bonded, either through a listed clamp or lug or through listed integrated bonding hardware.
  2. Rails and racking. Every rail section needs a bonded connection to the next, including splices.
  3. Mounting posts and structures. Ground-mount posts, pipe frames and roof attachments count as exposed metal.
  4. Combiner boxes and junction enclosures. Metal enclosures carry an EGC terminal for a reason. Our combiner box checklist walks through bonding and routing for multi-string installs.
  5. Inverter chassis. The inverter’s ground terminal connects to the same EGC network.
  6. Metal conduit and raceways. Metallic conduit must stay mechanically and electrically continuous, or carry its own EGC.

The grounding story also has a boundary. Inside the array, the EGC links every metal part together. At the building, that EGC connects to the grounding electrode system through the grounding electrode conductor (GEC) and the main bonding point. Utility-tied homes already have this system at the service panel, so you typically extend your EGC to it. Technical reports from the Solar America Board for Codes and Standards describe grounding as a documented, continuous path for fault current, where the integrity of every mechanical bond matters.

One practical point saves time and copper. Some mounting hardware, when UL 2703 listed for bonding, can serve as the bonding path between modules and rails. In that case you do not run a separate wire to every frame. The catch is that the listing applies only to the exact module, clamp and rail combination named in the manufacturer’s instructions. Swap in a different module or an off-brand clamp and the listed path may no longer apply.

Here are quick checks to run before you close up any section:

  • Look for bare metal contact at every bonding point, not painted or anodized surfaces without a bonding feature.
  • Confirm every enclosure has a lug or terminal for the EGC.
  • Trace the ground path with your eye from the farthest frame to the main ground. If you cannot follow it, an inspector will have trouble too.
  • Make sure no section is left floating, such as a short rail on an add-on row.

How do you ground a solar array step by step?

The workflow is the same for roof and ground mounts, apart from where the metal sits. Do the paperwork first, because it decides which parts you buy and how you connect them.

  1. Verify listings and read the instructions. Confirm your clamps, lugs and racking carry UL 2703 listings that cover your modules. Read the inverter’s grounding instructions, since they dictate EGC and GEC connections.
  2. Confirm permit and AHJ requirements. Ask which code edition applies and whether the inspector has electrode preferences. Settling this before you drill saves rework.
  3. Install the grounding electrode if needed. For a standalone or ground-mount system, drive ground rods per code. When you use more than one rod, space them apart and bond them together. Practical guidance on PV grounding methods notes that combined AC and DC grounding is permitted in some inverter configurations, though separate DC electrodes are an option.
  4. Bond the array metal. Attach listed bonding clamps or lugs to module frames and rails. Make sure every rail splice and every post carries a bonded connection.
  5. Run a continuous EGC. Route the conductor from the array through the combiner and inverter to the main grounding bus. Use listed lugs, and torque them to the manufacturer’s specification. Skipping a torque wrench is one of the quickest ways to create a loose connection, a point the SolarABCs technical report stresses along with using proper materials.
  6. Connect to the building system. Land the EGC or GEC at the main bonding point or the grounding electrode system, as the plan and code require.
  7. Verify and document. Test continuity from the farthest frame to the main bus, inspect every connection visually, label what needs labels, and photograph the work for the permit file.

Pro Tip: Photograph each bonding point before covering it, with the torque marking visible. Inspectors love proof, and it protects you if a question comes up later.

For roofs, plan your conductor route before the first module goes up, because wire is easier to place while the rails are open. For ground mounts, remember that the posts are exposed metal too, so budget extra conductor and lugs for them. If your system includes surge protection, our guide on verifying solar surge protection explains how those devices coordinate with the ground path.

How do you size conductors and choose ground rods?

Sizing is where DIY installs go wrong most often, mostly because people guess. The NEC gives tables, and your job is to read the right one for the right conductor.

Two conductors get sized differently. The EGC follows NEC 250.122, which keys the conductor size to the rating of the overcurrent device protecting the circuit. The GEC follows NEC 250.166 for DC systems and the related 250.66 tables for AC, which key off the system’s current-carrying conductors. When two rules produce two answers for the same run, the larger required size is the one to install. Check the exact requirement against the published NEC text for your adopted edition before buying wire.

For electrodes, keep these points in mind:

  • Ground rods are typically driven vertically, and your AHJ may have preferences on length and number.
  • When you install more than one electrode, keep them spaced apart and bond them together, as the earthing methods guidance describes.
  • Lightning protection electrodes are a separate system and should not be your only grounding electrode.
  • Soil conditions vary, so ask the inspector how they handle poor-conductivity ground.

A “UL listed” label alone can fall short. UL’s code guidance says that some products are listed for mechanical loading only, so confirm the bonding parameters in the specific listing.

To verify a part, search its model on UL Product iQ and read the listing details, not just the category. Check that the bonding capability and the module and rail combination match your install.

What changes with microinverters, off-grid batteries, and generators?

Special configurations do not remove the need for bonding. They change how the connections are made.

  • Microinverters and AC modules. Frames still get bonded, and you follow the inverter maker’s grounding instructions. Many inverters include ground-fault protection and EGC connections, and the SolarABCs report is a good reference for how those functions fit into a documented ground path.
  • Off-grid and battery-backed systems. Treat DC grounding on its own terms where the manufacturer recommends it, and do not ground the positive or negative conductor yourself unless the equipment instructions require it. Frames still bond to the EGC, as the earthing methods guidance explains.
  • Generator grounding is a different job. OSHA’s grounding factsheet notes that a portable generator used only for cord-and-plug equipment may use its frame as the grounding point. Permanent standby generators often need different treatment, such as a separately derived system or bonding at the transfer switch.

If you plan to pair solar with a generator, our solar plus generator setup checklist covers the layout questions, including where the neutral switching happens. Do not copy a generator’s grounding method onto an array, or the reverse.

What mistakes and corrosion problems should you avoid?

Most failed grounding comes from small, avoidable lapses, not exotic faults. These come up again and again:

  • Loose lugs from skipping the torque wrench
  • Bonding clamps biting into painted or coated surfaces instead of bare metal
  • Unlisted clamps that were never evaluated for your modules
  • Conductors routed so they strain or rub on sharp edges
  • A lightning electrode treated as the only grounding electrode

Corrosion deserves its own attention. Mixing dissimilar metals, such as copper against aluminum, speeds corrosion and can break continuity over time. Use approved, listed bonding components rated for your frame material and environment. For a deeper look, this dissimilar metals corrosion article explains how dissimilar metals can contribute to corrosion on metal systems.

Pro Tip: Recheck torque and look for green or white corrosion on lugs once a year, and again after severe weather. Photograph what you find so changes over time are easy to spot.

Corrosion visible around a solar grounding lug

Why we insist on listed parts and clear instructions

We sell solar energy systems, and we hear the same story from installers: the panels went up fine, but the grounding hardware was an afterthought. That is backwards. The bonding path is the part of your array that matters on the one bad day when something faults, and it deserves the same attention as module wattage.

Our position is simple. Pick listed hardware, confirm the listing covers your exact modules, follow the written instructions, and document the work. A carefully selected kit can help make choosing parts easier. We also think many owners should bring in a licensed electrician for the final tie-in and permit questions, even if they handled the rest themselves, because an inspector’s sign-off is part of a safe install.

Our product pages and installer guides exist to make that easier. If you hit a question about listings or code that this article does not answer, your AHJ and the manufacturer’s instructions are the final word.

— Gridwise

How we help you get a compliant solar setup

Grounding goes smoother when you choose parts carefully. Our Solar Energy Systems collection offers solar energy systems selected for durability and ease of use.

Gridwiseliving

If backup power is part of the plan, our Generators collection covers whole-home and portable options. The Powerhouse Gen 2 Whole Home Generator is one example, and our 50A Automatic Generator Transfer Switch pairs with generator setups where a transfer switch is needed. Because generator grounding works differently from array grounding, buying from one source and following one set of instructions helps you avoid crossed wires.

Buying pre-selected, compatible parts lowers the chance of improper bonding, and our team can point you to installation guides and product details before you commit. Browse the kits, compare the options, and check the listing on any bonding hardware before it goes on your roof. Start with the Solar Energy Systems collection and ask us what you need before checkout.

FAQ

Do solar panels need grounding?

Yes. Exposed metal parts of a PV array, including frames and mounting structures, must be bonded to an equipment grounding conductor under NEC 690.43. This applies regardless of system voltage, so small off-grid arrays are not exempt.

How do you ground a solar panel properly?

Bond every frame and rail with UL 2703 listed hardware, run a continuous EGC to the main grounding point, and torque all lugs to specification. Then check continuity and document the install, as the workflow above lays out.

Do I need to ground a generator the way I ground solar panels?

No, the two follow different rules. A portable generator used only for cord-and-plug loads may use its frame as the grounding point, while permanent standby units can need separately derived system treatment or transfer switch bonding.

Is a UL listed label enough for bonding hardware?

Not always. Some products are listed for mechanical loading only, so check the specific listing on UL Product iQ to confirm the bonding capability covers your modules and racking.

Sources

Back to blog