Our Summary : AS/NZS 4777.1:2024 – Grid Connection of Energy Systems via Inverters, Part 1: Installation Requirements

1. Removal of Stand-Alone Mode Definition

  • What Changed:
    • The 2024 standard no longer includes a “stand-alone mode” definition.
    • Previously, systems that could operate independent of the grid were sometimes lumped under “stand-alone” references. Now, those arrangements are typically categorized as Independent, Alternative, or Substitute supplies, each with specific requirements.
  • Why It Matters:
    • Eliminates confusion and overlapping requirements that once existed for hybrid or off-grid-capable systems.
    • Provides more consistent terminology, ensuring users apply the correct standard(s) for their specific supply arrangement.

2. Clear Demarcation of Standards

  • AS/NZS 5033:
    • Covers the PV array up to the input terminals of the inverter.
  • AS/NZS 4777.1:
    • Covers the installation requirements for the inverter energy system (IES).
  • AS/NZS 5139:
    • Applies to battery systems from the battery through to the inverter input terminals.
  • Why It Matters:
    • This distinct separation streamlines updates and reduces the confusion of having overlapping or redundant clauses in different standards.
    • Each standard has a well-defined scope, making it easier to maintain compliance and manage changes over a system’s lifecycle.

3. Phase Balance Update

  • What Changed:
    • A new 30 kVA limit is set for single-phase installations.
    • The permissible capacity depends on grid supply capacity or available overcurrent protection.
    • Stricter phase balance requirements apply particularly to commercial and industrial installations to ensure equitable load distribution across phases.
  • Why It Matters:
    • Helps prevent grid imbalances and voltage rise issues.
    • Provides a clear threshold for when multi-phase distribution or load balancing measures are required.

4. Interface Protection Replaces Central Protection

  • What Changed:
    • “Central protection” terminology is replaced by “interface protection.”
    • Systems under 200 kVA generally do not require interface protection (subject to DNSP approval).
    • For larger systems, DNSPs still have authority to require interface protection or additional protective measures.
  • Why It Matters:
    • Aligns Australian/New Zealand terminology with IEC standards and global best practices.
    • Offers greater flexibility for small to medium-scale IES by removing a layer of complexity and cost.

5. Minimizing Main Switches (Two Inverter Main Switches)

  • What Changed:
    • Limits the number of main switches for inverters to two per switchboard that also supplies other loads.
    • For systems with three or more inverters, an aggregation board must be installed so a single main switch can isolate all inverters.
  • Why It Matters:
    • Simplifies the isolation process, improves safety, and reduces confusion during maintenance or emergency shutdowns.
    • Ensures a more organized switchboard layout and fewer potential error points.

6. New Definitions

6.1 Inverter Power Sharing Devices (IPSD)

  • What They Are:
    • Technology that allows multiple users (e.g., apartment dwellers) to share a single PV system or a set of inverters.
    • IP sharing can also apply in other multi-occupancy or embedded network scenarios.
  • Key Requirements:
    • Inverters used with IPSDs must be tested to AS/NZS 4777.2.
    • Systems over 30 kVA require interface protection.
    • Must island in under 2 seconds upon loss of grid connection.
    • Signage and protective measures (like securing current transformers, system schematics) required at the main switchboard.
  • Why It Matters:
    • Facilitates new business models and more efficient use of rooftop PV in multi-tenancy buildings.

6.2 Vehicle-to-Grid (V2G) Technology

  • What Changed:
    • Mode 3 (AC) and Mode 4 (DC) electric vehicle (EV) chargers can now be used for reverse power flow to the grid (i.e., V2G).
    • Mode 1 & 2 (plug-in type chargers) do not allow reverse power flow and thus are outside AS/NZS 4777.1 scope.
  • Why It Matters:
    • Recognizes the growing importance of bidirectional EV charging in demand management and grid support.
    • Establishes clear rules for safe and compliant integration of EVs as part of the IES.

6.3 New Supply Type Definitions

  • Supplementary Supply
    • Operates in parallel with the normal supply but switches off when grid supply is lost.
  • Alternative Supply
    • Backup source (e.g., generator) providing secondary supply.
  • Independent Supply
    • Formerly considered “stand-alone,” can be grid-charged but no export allowed.
  • Substitute Supply
    • Single point supply during grid failure, max rating 15 A.
  • Why It Matters:
    • Provides a clear operational framework for each supply category.
    • Reduces confusion about when and how each supply type can connect or export.

7. Alignment with IEC Terminology

  • What Changed:
    • “Secondary protection” is now termed “interface protection.”
    • Reflects the ongoing efforts to harmonize Australian/New Zealand standards with international IEC standards.
  • Why It Matters:
    • Encourages global consistency and makes local standards easier to interpret for international manufacturers and designers.

8. Interface Protection for Multiple Electrical Installations

  • What Changed:
    • In multiple electrical installations (e.g., large embedded networks or precincts), interface protection is not required for systems over 200 kVA (assuming DNSP approval).
    • Systems under 200 kVA can also be exempt, but it depends on DNSP and local conditions.
  • Why It Matters:
    • Offers greater flexibility for large-scale and multi-tenant setups, reducing redundant protection systems.

9. Ganged Devices and Isolator Requirements

  • What Changed:
    • Ganged devices used to isolate more than one IES are considered one main switch in multiple IES scenarios.
    • If one inverter is within 3 meters and visible from the main switchboard, no adjacent AC isolator at the inverter is needed.
  • Why It Matters:
    • Reduces hardware duplication and simplifies installations, while still providing adequate safety and a single point of isolation.

10. DC and AC EVSE Supply Modes

  • What Changed:
    • Supplementary or Alternative supplies can be provided by both DC and AC EVSE.
    • EV arrangements that don’t parallel the grid (e.g., “Alternative Supply”) are not subject to AS/NZS 4777.2.
  • Why It Matters:
    • Expands the permissible configurations for EV charging solutions, supporting both AC and DC approaches.
    • Streamlines compliance where EV chargers do not feed power back to the grid.

11. Inverter Power Sharing Device (IPSD) Requirements

  • What Changed:
    • Clarifies that IPSDs must use AS/NZS 4777.2-compliant inverters.
    • For IES over 30 kVA, interface protection is mandatory.
    • Islanding requirements dictate a disconnect within 2 seconds of grid loss.
  • Why It Matters:
    • Ensures multi-user PV setups remain safe and reliable under both normal and abnormal grid conditions.
    • Mandates adequate labeling and protection to avoid confusion among multiple occupants.

12. Signage and Protection for IPSDs

  • What Changed:
    • The standard outlines comprehensive signage requirements for IPSDs, including schematic diagrams, warning labels, and secure current transformers.
    • Must be installed at the main switchboard or a clearly visible location.
  • Why It Matters:
    • Promotes safer operation, quicker identification of system components, and clearer emergency shutdown procedures.
    • Particularly important for multi-tenant buildings where multiple parties share the same generation resource.

Conclusion

AS/NZS 4777.1:2024 reflects the ongoing evolution of inverter energy systems and their integration with emerging technologies such as vehicle-to-grid and power-sharing devices. By removing ambiguous references (e.g., stand-alone mode), clarifying standards boundaries, and updating terminology to align with international norms, the 2024 standard aims to:

  • Simplify compliance for designers, installers, and system owners.
  • Enhance safety and clarity for multi-technology and multi-occupancy scenarios.
  • Foster innovative solutions (e.g., IPSDs, V2G) that support dynamic and flexible energy management.

Stakeholders involved in specifying, installing, or maintaining grid-connected inverters should carefully review these changes and ensure full compliance with AS/NZS 4777.1:2024, AS/NZS 4777.2, and any local DNSP requirements.

Disclaimer (Australia)

The information provided here is for general guidance and educational purposes only. We are not licensed electricians, accredited solar installers, or qualified to provide definitive technical or legal advice in Australia. While we strive to present accurate and up-to-date information, the standards and regulations governing electrical installations (including AS/NZS 4777.1) may change over time and can vary depending on your state or territory.

Ultimately, it is the responsibility of the licensed installer or qualified professional to ensure compliance with all applicable standards, regulations, and local network requirements. Always consult with a certified electrician, accredited installer, or relevant authority before commencing any installation, modification, or maintenance of grid-connected inverter systems. We disclaim all liability for any direct, indirect, or consequential loss or damage arising from reliance on, or use of, the information provided.