Earthing and lightning protection
Earthing gives fault current a planned path so a metal frame does not sit at a dangerous voltage. Lightning protection gives a strike a path that is not your inverter. They are related, and they are not the same wire thrown onto the terrace.
Three ideas to keep apart
Equipment earthing
Metal that a person can touch, such as the module frame, the structure, and the inverter body, is bonded so a fault trips the protection instead of waiting for a hand.
Functional earthing
Some inverter designs use an earth reference for the electronics to work as intended. That connection follows the manual. It is not a licence to improvise a rod.
Lightning protection
A lightning path is designed for a strike: air terminals or the building's existing system, down conductors, and an earth electrode arrangement. A surge device at the inverter is the last stage, not the whole system.
What gets bonded
Module frames should be bonded to the structure, and the structure to the earth system, with conductors and lugs sized for that job. Paint and a loose clamp are not a bond. The inverter manual states its own earth terminal. Follow that terminal. Do not assume the AC plug earth is enough for the array.
Earth electrodes are rods, plates, or other electrodes in soil that can actually dissipate current. A rod in dry rubble is a drawing, not an earth. Testing measures the result. It does not invent a good result.
No universal resistance on this page
Earth resistance targets depend on the applicable standard and on whether the electrode is for equipment earth, a lightning earth, or both. Publishing one ohm value for every Indore roof would be wrong. The test method and the target belong in the design for that installation, and the reading should be recorded.
Inspection
A useful inspection looks at broken bonds, green corrosion on lugs, a disconnected down conductor, and a surge device that has already operated. It is visual and electrical. It is not a homeowner job with the array live.
After roof work by another trade, check that nobody has cut an earth link to run a pipe. That happens more often than a dramatic strike.
Common mistakes
One loose wire called 'earthing'
If it is not continuous to an electrode, it is decoration.
Mixing the lightning rod into the inverter at random
A strike current should not be invited through the inverter chassis on its way to soil.
Never testing
Soil dries, clamps rust, and a reading from the installation day does not last forever.
Where to read further
Earthing questions
What earth resistance should I demand?
Ask which standard and which electrode the designer is using. This page deliberately does not print a single ohm target.
Does a lightning arrestor replace earthing?
No. Lightning protection and equipment earthing are specified together. One does not cancel the other.
Can I add an extra rod myself?
No. An extra rod in the wrong place, bonded with the wrong conductor, can make the installation less safe. It is a design change.
Related guides
- Solar panel technologyCells, module types, efficiency, heat, degradation, and why DCR matters for the central scheme.
- Solar inverter guideThe inverter turns panel current into household current and decides what happens when the grid fails.
- Solar structure and mountingThe structure holds the modules to the roof. Its size is an engineering result, not a catalogue guess.
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