EMC Zoning Concept

EMC Zoning Concept for PV Installations
The EMC zoning concept (Electromagnetic Compatibility) divides an installation into Lightning Protection Zones (LPZ). Each zone represents a different exposure level to lightning currents and electromagnetic induction. For PV systems, the following definitions and measures apply:

 

LPZ 0A – Unprotected outdoor zone

This is the area where the PV installation is located, such as on the rooftop. If no lightning protection system (LPS) is present, the system is exposed to:

  • Direct lightning strikes;

  • Full lightning current surges on cables and inverters.

In this situation:

  • A Type 1 SPD (surge protection device) must be installed on the DC side;

  • This also applies when an LPS is present and physically connected to the PV system;

  • Equipotential bonding must be established between the external LPS and the grounding point at the inverter.

     

LPZ 0B – Protected outdoor zone

This zone is within the protective angle of lightning air-termination rods, without direct conductive connection to the PV installation:

  • Protected against direct strikes;

  • Electrically isolated from the LPS by maintaining the required separation distance.

Only induced voltages may occur here.
→ A Type 2 SPD is sufficient for protection.

 

LPZ 1 – Incoming infrastructure

In this transitional zone:

  • The lightning current is partially distributed through the LPS and grounding system;

  • Additional SPDs are installed at the zone boundary.

If the PV system is in LPZ 0B and the inverter is placed indoors (LPZ 2), then:

  • A Type 2 SPD on the DC side is sufficient.
    However, if there is physical coupling with LPZ 0A (e.g. mounting frame bonded to LPS), then:

  • A Type 1+2 SPD is required on the DC cabling.

 

LPZ 2 – Inside the inverter enclosure

This zone is formed by the metal enclosure of the inverter:

  • Provides additional shielding against induced currents;

  • Supplemental SPDs further reduce residual surge energy.

→ SPDs must be placed as close as possible to the inverter.

EMC zoneconcept

 

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