GROUNDING PLATE

The ULAMEX grounding plate is a dedicated equipment bonding component that establishes a reliable electrical earth connection between PV modules, mounting rails, and the system’s earth conductor. Manufactured from H17 stainless steel (1.4016 / AISI 430) with serrated contact surfaces, this 40x40x5.5 mm plate with 8 mm bolt hole penetrates the anodized oxide layer on aluminum profiles and module frames to create a low-resistance metallic path to ground — a critical safety requirement under IEC 62305 (lightning protection) and IEC 62548 (PV array design requirements). Without proper equipment grounding, a lightning strike or insulation fault can leave the entire metal structure of a solar installation at a dangerous potential relative to earth, creating a lethal shock hazard for maintenance personnel and a fire risk for the building.

Installation Guidelines

The grounding plate is installed at the junction between two components that require electrical bonding — typically between a PV mounting profile and a module frame, or between two rail sections joined by a profile connector. Position the plate with its serrated face pressed firmly against the aluminum surface. As the M8 bolt is tightened, the serrations bite through the anodized oxide layer (typically 5–25 micrometres thick on EN AW-6060 T6 profiles) and establish direct metal-to-metal contact with the underlying aluminum substrate.

Recommended tightening torque: 12–14 Nm for M8 connections. This torque must be sufficient to deform the serrations into the aluminum surface — under-torquing will leave the oxide layer intact and result in a high-resistance connection that fails to provide effective fault current dissipation. Verify the connection resistance with a low-resistance ohmmeter (micro-ohmmeter): the measured value should be below 0.1 ohm between any point on the module frame and the earth busbar.

Connect the earth conductor (typically 6 mm2 or 10 mm2 copper, yellow-green insulated) to the grounding plate using a ring terminal crimped to the cable and secured under the same M8 bolt or an adjacent bolt hole. All earthing connections must be accessible for periodic inspection as required by local electrical codes.

In installations with more than 10 modules, it is common practice to bond each module frame to the mounting rail via a grounding plate at one clamp position per module, then connect the rail to the building’s main earth bar via a single earth conductor run. This star-to-bus topology minimises copper usage while maintaining equipotential bonding across the entire array.

Applications in Photovoltaic Mounting

• Module-to-rail bonding — the primary application; a grounding plate installed under one clamp per module establishes the electrical connection between the anodized module frame and the anodized mounting rail
• Rail-to-rail bonding — at profile connector joints, a grounding plate ensures electrical continuity across the splice, even if the connector itself does not penetrate the oxide layer
• Rail-to-earth-conductor connection — the plate provides a stainless steel mounting point for the ring terminal of the copper earth cable that connects the array frame to the building’s earthing system
• Lightning protection equipotential bonding — in systems with external lightning protection (IEC 62305 LPS), grounding plates connect the PV mounting structure to the lightning protection down-conductors, ensuring the entire installation is at the same potential during a strike
• Ground-mount solar farms — on large-scale ground-mount arrays, grounding plates bond each table section to the site-wide earthing grid, typically connected to driven earth rods at regular intervals

Material Properties

H17 stainless steel (1.4016 / AISI 430) is a ferritic chromium stainless steel selected for grounding plates because of its unique combination of properties required for long-term electrical bonding in outdoor environments:

• Corrosion resistance: The 16–18% chromium content ensures the plate itself does not corrode and degrade the earth connection over the 25–30 year installation lifetime
• Hardness: Ferritic stainless steel at 5.5 mm thickness provides the hardness needed for the serrated teeth to penetrate the aluminum anodized layer under bolt torque — softer materials would deform before breaking through the oxide
• Electrical conductivity: While lower than copper or aluminum, stainless steel conductivity is sufficient for equipment bonding applications where the current path is short (plate thickness) and the cross-section is large (40×40 mm face area)
• Galvanic compatibility: The electrochemical potential difference between ferritic stainless steel and aluminum is small enough that galvanic corrosion at the bonding point is negligible over the installation lifetime, particularly when the joint is protected from persistent moisture
• Magnetic properties: The magnetic nature of ferritic stainless has no effect on grounding function and can assist during installation by allowing plates to be held on magnetic tool bits

Compatibility

ULAMEX grounding plates are compatible with the following components in the ULAMEX photovoltaic mounting system:

• PV Profile 40×40 mm and 80×40 mm — plate seats on the flat top surface of the profile rail
• Aluminum clamps — install the grounding plate between the clamp base and the profile surface at one clamp position per module
• Profile connectors — install at the rail splice point to maintain earth continuity across the joint
• M8 fasteners — the 8 mm hole accepts standard M8 bolts, T-bolts, or the existing clamp bolt
• Standard earthing accessories — compatible with 6 mm2 and 10 mm2 ring terminals, earthing lugs, and copper earth bars

Frequently Asked Questions

Do I need a grounding plate on every clamp?

No. Standard practice requires one grounding connection per module frame, typically at one clamp position per module. The remaining clamps provide mechanical fixing only. The mounting rail itself acts as the bonding conductor between all modules in the row, provided the rail-to-rail splice points are also bonded with grounding plates.

Can I use a standard flat washer instead of a grounding plate?

No. A standard flat washer does not have serrated teeth and cannot penetrate the anodized oxide layer on aluminum profiles and module frames. Without oxide penetration, the electrical resistance of the connection is too high for effective fault current dissipation, and the grounding connection does not comply with IEC 62305 or IEC 62548.

What earth conductor size do I need?

For residential PV systems (up to approximately 15 kWp), a 6 mm2 copper earth conductor is typically sufficient. For commercial and industrial installations, 10 mm2 or 16 mm2 may be required depending on the prospective fault current and local electrical codes. Consult your electrical designer or the relevant national wiring regulations.

Is H17 stainless steel (1.4016) suitable for earthing applications?

Yes. 1.4016 ferritic stainless steel provides adequate electrical conductivity for equipment bonding (short-path, large cross-section applications) and excellent long-term corrosion resistance to maintain the earth connection over the full installation lifetime. It is widely used in earthing and bonding applications across the European PV industry.

Need grounding plates for your solar installation? Request a quote — ULAMEX supplies equipment bonding components at B2B wholesale conditions alongside our complete photovoltaic mounting range. Single-source procurement, single delivery, Europe-wide.