Sector applications · Complies to IEC 61400-24 · IEEE 80
Ground-mounted PV, Wind and BESS Protection
Ground-mounted solar plants, wind turbines and battery energy storage systems cover large open areas and are highly exposed to lightning. Protection combines a site-wide earthing grid, air termination where needed, coordinated surge protection on DC, AC and data lines, and storm warning for people on site.
When it applies
- Utility-scale PV plants with string or central inverters at up to 1,500 V DC
- Wind turbines and wind-farm collector systems
- Containerised battery energy storage systems
- Hybrid plants with a pooling substation
When it does not
- Rooftop systems — see the rooftop PV solution
- The grid substation itself, which follows the substation solution
- Turbine blade receptors and internal down conductors, which are the turbine manufacturer's design
How the system works
- AssessA lightning risk assessment and the sector's own standard set the protection level.
- Earth and bondEvery structure, frame and cabinet is joined to one earthing system.
- Protect the linesCoordinated surge protective devices are fitted on power, DC, RF and data lines.
- Monitor and maintainCounters and status contacts show what happened; inspection keeps the system in service.
Coordinated surge protection
Each device takes its share. The Class I device diverts lightning current at the service entry; Class II and III devices bring the remaining voltage below what the equipment can withstand.
Design parameters
The values a consultant or contractor needs to fix before the system is drawn.
| Parameter | Typical value or rule | Reference |
|---|---|---|
| Earthing | Meshed grid linking mounting structures, inverter stations and containers | IEC TR 63227 · IEEE 80 |
| PV DC surge protection | Type 2 or Type 1+2 at combiner boxes and inverter inputs; Ucpv at least 1.2 × open-circuit voltage | IEC 61643-32 |
| Wind turbines | Designed to LPL I unless a risk assessment shows otherwise; SPDs at generator, converter, pitch and control | IEC 61400-24 |
| BESS | SPDs on DC battery strings, AC connection and battery management communication; containers bonded to the grid | IEC 62305-4 |
| Data and control lines | SPDs at both ends of SCADA, weather-station and tracker communication cables | IEC 61643-22 |
| Storm warning | Thunderstorm warning system to stop outdoor work in time | IEC 62793 |
Solution pack: component BOQ
Each line opens the LPES product category. Part codes and final quantities are confirmed on your quote from the drawings.
| Component | Role in the system | Quantity rule |
|---|---|---|
| DC & PV SPDs | DC surge protection at combiner boxes and inverter stations; DC surge protection for battery strings and auxiliary supplies | One set per combiner and per inverter DC input; One set per battery container DC bus |
| AC Power SPDs | AC surge protection for turbine and collector equipment | Per turbine: generator, converter and auxiliary supply |
| Earth Mats & Grids | Site earthing grid and inverter-station mats | Grid length from the design; one mat per inverter station and container |
| Lightning Detection & Warning | Thunderstorm warning for site safety and operations | One system per site |
From design to handover
- Survey soil resistivity and assess lightning risk across the site
- Design the earthing grid and link every structure, station and container
- Coordinate SPDs on DC, AC and data lines
- Install, weld and bond; fit storm warning
- Test earthing and SPD installation and hand over records for the plant file
Services for this solution
Industries that use it
What the standards require
Checked against the current editions held in the LPES standards library.
- IEC 62305-2:2024
- Risk to life and physical damage is compared with a tolerable risk of 10⁻⁵ per year; failure of internal systems is judged separately as a frequency.
- IEC 62305-4:2024
- A coordinated SPD system protects against conducted surges only. Radiated fields need shielding and cable routing.
- IEC 62305-4:2024 Cl. 7
- Where an external LPS exists, a Class I (Type 1) SPD is required at the service entry.
- IEC 62305-4:2024
- Earthing conductor to the SPD: 16 mm² copper for Class I, 6 mm² for Class II and 1.5 mm² for Class III.
- CEA Safety Regulations 2023, Reg. 38(3)
- Lightning protection is addressed for multi-storeyed buildings above 15 m and listed public premises such as airports, hospitals and hotels.
- IEEE 80-2013
- A substation grid is judged by touch and step voltage against the tolerable limits, not by its resistance alone.
Regulation and standards cross-check
What Indian regulation and the wider standards add to this solution. Paraphrased; confirm against the current official text, amendments and state notifications before relying on a clause in a tender or inspection.
| Standard | Clause | What it requires |
|---|---|---|
| CEA Safety Regulations 2023 | Reg 121 | Solar plants need lightning and overvoltage protection with lightning arresters, a surge protective device with arc-extinguishing capability in every combiner box, earth-fault protection with insulation monitoring, and earthing of all array structures, frames and enclosures with welded strip connections. |
| IS 3043:2026 | Clause 11.3 | On solar plants the a.c. side is TN or TT and never TN-C. A separate protective conductor is always required, frame bonds are at least 6 mm² copper, and separate electrodes for the d.c. side, a.c. side, inverter or lightning protection are non-compliant. |
| CEA Safety Regulations 2023 | Reg 77 | Owners of overhead lines, substations and generating stations exposed to lightning must divert lightning surges to earth. The arrester earthing lead is kept as short and straight as possible, does not pass through steel pipe, and goes to a separate vertical electrode or to a junction of the earth mat. |
| CEA Safety Regulations 2023 | Reg 50 | Above 650 V the whole switchyard or substation, including non-current-carrying metal, is connected to an earthing system or mat that limits touch and step potential and earth potential rise, including potential transferred through earth wires, cable sheaths, fences and pipelines. |
| IEC 61936-1:2021 | 8.6, Annex E | For outdoor high-voltage installations the analysis method and protection level against direct strokes are agreed with the user. Lightning rods and shield wires shall be earthed. Buildings and similar structures follow IEC 62305. |
| IEC 61936-1:2021 | 10.2.1, Annex B, Annex C | The safety criterion is the permissible touch voltage against fault duration, about 650 V at 100 ms falling to about 120 V at 1 s. Meeting the touch-voltage limit generally satisfies step voltage. The IEEE 80 curve is an allowed alternative. |
| IEEE Std 80-2013 | Clause 17 | Special areas are checked one by one: the fence, with a perimeter conductor about 1 m outside it or bonding, operating-handle mats, cable sheaths, surge arrester earthing, and potentials transferred by communication circuits, pipes, rails and low-voltage neutrals. |
What we ask for before design starts
- Single-line diagram with sources, operating modes and earthing arrangement
- Equipment list with impulse withstand levels
- Cable routes and every point where services enter
- Fault levels and protection clearing times
- Existing earthing and lightning protection records
- Site layout with fences, pipes, rails and neighbouring installations
Engineering depth: from the LPES Knowledge Hub
Topic studies written against the current standards. Open each part for the method, the mistakes to avoid and the checklist.
IEC 62305-4:2024 · LPES Knowledge Hub H-63
Free-field PV power plants with multiple earthing and a meshed earthing system
A ground-mounted, "free-field" PV power plant is a fundamentally different lightning-current-sharing problem from a rooftop array: instead of a small number of discrete down conductors on a building, the plant sits on an extensive earth-termination system, usually a mesh (Figure F.3 shows 20 m × 20 m), with many earthing points spread across the site. Clause F.3 of IEC 62305-4:2024 gives a simplified, practice- and modelling-derived set of current values (Table F.3) for the partial lightning current that flows through the DC conductors, via the SPDs, into this kind of multiply-earthed, meshed installation under LPL III — so that DC-side SPDs on a free-field solar plant can be specified against a current level that reflects this specific earthing geometry, rather than reusing the rooftop figures of Table F.1/F.2 or assuming a number.
How it is applied
- confirm this topic applies: is the installation a ground-mounted, free-field PV plant with multiple earthing points and a meshed earth-termination system?
- confirm the LPL from the site's own IEC 62305-2 risk assessment; F.3.1 states LPL III is the generally-reached result for this class of installation, but this must be verified for the specific project, not assumed by default.
- compare the actual site's mesh size and earth resistivity against the Table F.3 reference case (20 m × 20 m mesh); where the actual mesh is coarser, or the resistivity higher, than the reference case, treat Table F.3's figures as a starting point to be increased, per the qualitative drivers named in F.3.2, rather than as an exact fit.
- select the SPD family: limiting/combination (series, Class I/II) or switching/combination (parallel, Class I), and read the matching Iimp/In value pair from Table F.3 for LPL III.
- specify the DC-side SPD's rated Iimp (and, for the limiting/combination type, In) at or above the applicable Table F.3 value.
- where the strike could land close to the inverter housing itself (a realistic possibility on a large open site with the inverter station as a prominent structure), apply Table F.3's own NOTE 2 caution and consider a higher rating for SPDs protecting that specific location rather than the general-area reference value.
- specify shielded DC cable (or metallic ducting) between the PV array and the central inverter station, bonded at both ends to the local bonding bars, and rated to carry partial lightning current as its own down-conductor-equivalent path.
- on a multi-string-inverter plant, apply Table F.1's rooftop values (cross-referenced by F.3.3 itself) to the Class I SPDs on the AC side of the string inverters and the low-voltage side of the central transformer, and allow Class II SPDs on the short DC run from a PV string to its own string inverter, provided that run carries only one set of SPDs.
- where the site departs materially from the Table F.3 reference case (unusual mesh size, high resistivity, or any other driver named in F.3.2), commission a specific current-sharing calculation rather than relying on the simplified table.
Common mistakes
- Reusing the rooftop Table F.1/F.2 figures (or Equation F.1) for a free-field, meshed-earthing installation instead of Table F.3 — the two clauses address genuinely different current-sharing physics and are not interchangeable.
- Treating Table F.3's 20 m × 20 m mesh, LPL III reference case as universal, without checking the actual site's mesh size, resistivity, and risk-assessed LPL against it, when F.3.2 explicitly names both mesh size and resistivity as drivers that push the real figure up or down.
- Applying a single, uniform SPD rating across an entire large site without considering Table F.3's own NOTE 2 — that current exposure can be materially higher near the inverter housing than the general-field reference value.
- Omitting the shielded-cable/bonded-shield recommendation for the DC run to the central inverter station, on the assumption that a free-field plant's greater physical separation from any single down conductor makes shielding unnecessary — F.3.3 makes the same recommendation here as F.1 makes for the rooftop case.
- Confusing the switching/combination (parallel) SPD's single Iimp requirement in Table F.3 with the limiting/combination (series) SPD's two-parameter (Iimp and In) requirement, and applying the wrong pairing when specifying or purchasing.
- Assuming LPL III applies without confirming it from the project's own IEC 62305-2 risk assessment — F.3.1's "generally leads to LPL III" is a description of the typical outcome for this installation class, not a substitute for doing the assessment.
Design checklist
- Confirmed the installation is a ground-mounted, free-field PV plant with multiple earthing and a meshed earth-termination system.
- Confirmed the project's own IEC 62305-2 risk-assessed LPL, rather than assuming LPL III by default.
- Recorded the site's actual earth-termination mesh size and compared it against the Table F.3 reference case (20 m × 20 m); flagged any coarser mesh as a reason to increase the reference figures.
- Recorded the site's earth resistivity (from a ground resistivity survey) and compared it qualitatively against the reference case; flagged high-resistivity sites as a reason to increase the reference figures.
- Selected the DC-side SPD family (limiting/combination series, or switching/combination parallel) and read the matching Iimp/In requirement from Table F.3.
- Applied Table F.3 NOTE 2's caution for any SPD protecting equipment near the inverter station or other strike-attractive structures, rather than using the general-field reference value uniformly.
- Specified shielded DC cable or metallic ducting between the array and the central inverter station, bonded at both ends to the local bonding bars.
- For multi-string-inverter plants, confirmed which SPDs use the Table F.1 (rooftop, cross-referenced) rating versus the short-run Class II relaxation, on the same basis as the related topic T-62.
- Where the site departs materially from the Table F.3 reference case, commissioned a specific current-sharing calculation instead of relying on the table.
Try the numbers
Protection level explorer
- Rolling-sphere radius
- 45 m
- Mesh size
- 15 × 15 m
- Down-conductor spacing
- 15 m
- Peak current covered
- 100 kA
- Coefficient ki
- 0.04
- Interception efficiency
- 90%
Values from IEC 62305-1 and IEC 62305-3. The level for your structure comes from the risk assessment.
Tolerable touch and step voltage
- Tolerable touch voltage
- –
- Tolerable step voltage
- –
- Surface derating Cs
- –
IEEE Std 80-2013, equations 27 and 29 to 33. Set the thickness to 0 for no crushed-rock layer. These are limits; the grid design must keep mesh and step voltage below them.
What we find on audits
- Equipment earths and lightning earths kept separate
- Surge protective devices chosen without coordination or the right voltage rating
- Long connecting leads that add kilovolts to the protection level
- Data and signal lines left unprotected while power lines are protected
- No inspection after a strike, so failed devices stay in service
What you receive: the LPES Protection Passport
- As-built drawings of the installed system
- Risk assessment and design calculations
- Test results: earth resistance, continuity, SPD checks
- Component list with part codes and type-test references
- Inspection schedule for the protection level
Lightning to Load: one accountable partner
- Assess
- Design
- Specify
- Supply
- Implement
- Verify
- Assure
Standards basis
IEC 62305-2, -3 and -4:2024 (Ed. 3) · IEC 61643 series · IEEE 80-2013 · IEC 61936-1:2021 · IS 3043:2026 · CEA Safety Regulations 2023 · IS 732:2019 · IEC 60364-6:2016 · IEC 61936-1:2021
Reviewed by LPES engineering, November 2026. Clause and table numbers follow IEC 62305:2024 (Edition 3) and IS 3043:2026.
Questions engineers ask
Do ground-mounted PV plants need air terminals?
Often the earthed mounting structure and coordinated SPDs are sufficient; inverter stations and substations are usually given air termination. The risk assessment decides. Earthing System Design
What SPD voltage is needed for a 1,500 V plant?
A PV SPD with a continuous operating voltage of at least 1.2 times the array open-circuit voltage, in a 1,500 V DC class. DC & PV SPDs
How is a battery container protected?
It is bonded to the site grid and fitted with SPDs on its DC bus, AC connection and communication lines. DC & PV SPDs
Why is the earthing grid site-wide?
Linking all structures limits potential differences between them during a strike, which is what damages inverters and data lines. Earth Mats & Grids
What does a storm warning system do?
It detects approaching thunderstorms and gives time to stop outdoor work and secure operations. Lightning Detection & Warning
Get this solution quoted for your site
Send the drawings or the basic dimensions. LPES returns the design parameters, the BOQ with part codes and the price in one offer.
