Glossary · Lightning, earthing, fire safety
PV earthing and equipotential bonding
Connecting PV frames, rails and structures to the building’s earthing; under PUE:2026 the earthing must be common with the building.
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Definition
The metal parts of a PV plant — panel frames, rails, trusses — can become live if insulation fails. To keep that from going unnoticed, they are bonded together and to the building’s main earthing bar (MEB). Section 712.54 of DSTU HD 60364-7-712:2022 covers earthing and protective conductors of PV installations.
PUE:2026 (cl. 1.7.59) requires one common earthing for the installation and the building. In practice: a separate electrode under a ground-mounted array is possible, but only in addition, and it is also bonded to the building’s MEB. Two independent electrodes on one site can sit at different potentials during a strike or fault, and the difference falls on the equipment insulation.
If the building has lightning protection, bonding the frame ties in with the separation distance: the frame is either isolated from the LPS or bonded to it with a conductor rated for a partial lightning current (DSTU EN 62305-3:2021). We do not give a specific electrode resistance or a conductor size without an LPS here: the electrician’s design sets them.
What it looks like on site. On a roof, panel frames are bonded to the rails, the rails of neighbouring rows to each other, and a conductor runs from the array to the MEB by the shortest route. On a ground frame, the structure is bonded to the electrode, and that to the building MEB. After installation, continuity of the protective conductors is checked with an instrument. The earthing resistance, the conductor size without an LPS and the type of joints are set by the electrician's design: we do not give them here, because the norms we hold give no source for these numbers for PV. Also think about the SPDs: their lead to the bar must be short.
How Solispec applies it
Solispec’s installation and report texts follow PUE:2026 cl. 1.7.59: for a rooftop array, bond frames and rails together and to the building MEB (712.54); for a ground truss, bond the frame electrode to the MEB, separate rods only in addition. Continuity of protective conductors is checked with an instrument, and the resistance comes from the electrician’s design: the engine writes no number without a source.
Norms and clauses
- PUE:2026, cl. 1.7.59
- DSTU HD 60364-7-712:2022, section 712.54
- DSTU EN 62305-3:2021
Related terms
- Surge protective device (SPD)A device that limits lightning and switching surges in PV circuits; its type depends on whether the building has lightning protection.
- Separation distance s (lightning protection)The minimum gap between a PV array and lightning down conductors at which no spark flashes over (DSTU EN 62305-3:2021, cl. 6.3).
- Lightning risk assessmentThe DSTU EN 62305-2:2022 calculation deciding whether a building with PV needs external lightning protection; there is no "PV means LPS" rule.
- Allowed connection powerThe power stated in the grid connection contract; the total power of the PV inverters may not exceed it.
- PUE:2026 for solar plants: what changedNorms explained
- DSTU HD 60364-7-712:2022: the electrics of PV systemsNorms explained
- DSTU EN 62305-1…4: lightning protection for solar plantsNorms explained
Solispec’s calculation is preliminary: for a design it has to be checked by an engineer. The values and clauses follow the current editions of the norms on the date of the page.