Grounding of PV installations

In the market, there is still much discussion about grounding of solar panel installations. But what exactly is grounding? Grounding means connecting them to the earth through an additional cable so that in case of overload, the excess electricity safely dissipates into the ground. Additionally, grounding protects your solar panels, as they won’t become defective or catch fire due to sudden increases in current.

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As of October 1, 2020, the new NEN1010 regulations make grounding of a solar panel installation mandatory. The mounting system is considered a metal structure and must be grounded accordingly. However, the solar panels themselves are double-insulated and do not need to be grounded. To ensure the safe installation of a solar panel system, it is essential to follow the guidelines specified in NEN1010.

Check out Conduct’s PV grounding kits.

NEN 1010, the main standard for electrical installations in buildings

NEN 1010 specifies the safe installation, expansion, and adaptation of low-voltage installations. Additionally, the standard provides clarity on inspections and checks during project completion, whether for residential, commercial, or industrial buildings.

According to NEN1010:2020, grounding is mandatory:

  • When the array is in the vicinity of a lightning conductor.
  • When a transformerless inverter is used.

Grounding is recommended due to the alternating current characteristics of solar panels. Kees Compaan from KWx explains:

How does this work in practice?

Different methods should be considered:

411.3.1.1 Safety grounding

Every current circuit must have a protective conductor connected to the relevant earth terminal.

If there is no lightning protection system: 6mm²
If there is a lightning protection system, the distance between the PV (or cable tray) and the lightning protection system should be considered: < 50cm = connect, >50cm do not connect:

  • Not connected PE = 6mm²
  • Connected PE = 16mm²

Note: When bonding the lightning protection system to the PV installation, use 16mm².

411.3.1.2 Protective equipotential bonding

  • In every building, the earthing conductor, main earthing bar or terminal, and the following conductive parts must be connected to the protective equipotential bonding: metal pipes for indoor facilities, such as gas and water;
  • External conductive parts of the building’s structure, if accessible during normal use, including metal central heating and air conditioning systems;
  • Metal reinforcement of reinforced concrete structures, if accessible and reliably interconnected.

If such conductive parts come from outside the building, bonding must be done as close as possible to the point of entry.

712.542.101 Potential equalization of metal frames in a PV system

  • Where potential equalization is necessary, the metal frames to which the PV panels are attached, including the metal cable tray systems, must be equalized.
  • The equalization conductor must be connected to a suitable grounding point.

NOTE 1 Lightning protection system grounding points are not considered suitable for this purpose.

IMPORTANT: In NPR5310 section 6.3.1 Grounding of metal parts of a PV system, it is stated:

If the metal parts of the PV system are connected to a lightning protection installation, no connection may be made to the electrical installation grounding system.

This is incorrect and even poses a fire hazard. Conduct is in discussion with the responsible parties to have this paragraph removed from the next edition of NPR5310.

712.542.3.101 Functional bonding conductor
The bonding conductors (insulated or uninsulated) must have a minimum cross-section of 4 mm² in copper, or equivalent.

514.3.1.2 Protective conductor
Protective conductors must be identified with the color combination green-yellow, and this color combination may not be used for any other purpose.
Insulated protective conductors for grounding and equipotential bonding must be identified as protective conductors.

514.3.7 Omission of identifications
Color or marking identification is not required for metal structural parts of the building or external conductive parts used as protective conductors. However, it is recommended for safety purposes to apply color coding.

Click here for information about RoofSupport grounding kits.

Inspection
Before commissioning, an inspection must take place. Part 6 of NEN1010:2020 describes the general inspection. Additionally, NEN-EN-IEC 62446 provides additional requirements for system documentation, testing before system operation, and the first inspection.

If you have any further questions about grounding PV installations, please feel free to contact us.