The AS/NZS 4777.1:2024 standard is now released! It introduces several significant changes that simplify regulations, clarify definitions, and enhance system safety. Here’s a summary of the key updates and their implications:

Removal of Stand-Alone Mode Definition

The new standard does not recognize the stand-alone mode definition. This clarity of standards has made it easier to understand and adopt since it lacks complications that previously defined stand-alone mode.

Clear Demarcation of Standards

It clearly articulates what each standard will apply to, and these are:

AS/NZS 5033

Now applies to the PV array as far as the input terminals of the inverter.

AS/NZS 4777.1

Now deals with the installation of inverter energy systems.

AS/NZS 5139

Now covers battery systems through to inverter input terminals.

This clear separation helps streamline the management of changes and reduces the need for aligning multiple standards.

Phase Balance Update

A new limit of 30 kVA is set for single-phase installations. The capacity is defined on grid supply capacity or available overcurrent protection. The revision is quite substantial in commercial and industrial due to the setting of concrete phase balance requirements.

Interface Protection Replaced Central Protection Definition

Central protection is now referred to as “interface protection” and is not required for systems under 200 kVA. This will depend on your application with your DNSP, and they need to approve it.

Minimizing Main Switches – Two Inverter Main Switches

The new standard limits the number of main switches to two per switchboard, also carrying other loads, and for those systems with three or more inverters, an aggregation board shall be installed to ensure one single main switch controls the inverter system, simplifying system management and enhancing safety.

New Definitions

Inverter Power Sharing Devices (IPSD)

The newest technology introduced is the Inverter Power Sharing Devices (IPSD) that enable a few installations, in apartment buildings, for example, to share one PV system or a few inverters. This has been a technological breakthrough in the usage of a PV system in buildings where there are several tenants.

Vehicle-to-Grid (V2G) Technology

Vehicle-to-grid technology has been approved for both Mode 3 and Mode 4 EV chargers, where Mode 3 applies AC connections and Mode 4 uses DC power from the vehicle. This approval is a step forward in flexible and efficient energy management.

New Supply Type Definitions

The standard explains a number of supply types, including:

Supplementary

This operates in addition to the normal supply and switches off in case the grid supply is lost.

Alternative

Includes backup options like generators, providing a secondary supply.

Independent

Originally stand-alone, charging from the grid, no export is allowed.

Substitute

Single point supply, one outlet during grid failure, rating maximum 15 amps.

These definitions provide functionality and requirements for various power supplies.

Alignment with IEC Terminology

The standard now aligns with the IEC terminology, with the change in terms such that “secondary protection” now reads “interface protection.” This ensures harmony and clarity.

Interface Protection for Multiple Electrical Installations

In multiple electrical installations, such as embedded networks, interface protection is no longer required on systems over 200 kVA. This means there is greater flexibility in more extensive applications.

Ganged Devices and Isolator Requirements

Ganged devices used for the isolation of more than one IES are considered one main switch in systems with multiple IES. Further, an adjacent AC isolator is not needed at each inverter if one inverter is within 3 meters of a main switchboard and others are visible from it.

DC and AC EVSE Supply Modes

Supplementary or Alternative supplies can now be provided by both DC and AC EVSE. The flexibility provides multiple installation scenarios.

EVs with Alternative Supply Arrangements

It follows that EV’s with Alternative Supply arrangements are not subject to AS/NZS 4777.2 since they do not parallel the grid. It simply means some EV arrangements have had compliance simplified.

Mode 1 & 2 Charging Devices

Because no reverse power flow is allowed, the plug-in types of Modes 1 and 2 charging devices are not within the scope of AS/NZS 4777.1. Details for these are contained in Appendix B of AS/NZS 3000.

Mode 3 & 4 Allow Reverse Power Flow

The modes that allow reverse power flow are Mode 3 and Mode 4. Mode 3 addresses AC EVSE, while Mode 4 applies to DC connections. For reverse power transfer, the installation of these modes has to be as permanent equipment.

Inverter Power Sharing Devices (IPSD) Requirements

IPSDs shall utilize inverters tested to AS/NZS 4777.2, shall have interface protection for IESs over 30 kVA, and shall island in under 2 seconds on loss of grid connection of any distribution board. The requirements of performance for the IPSDs are detailed in the standard.

Signage and Protection for IPSDs

An installation of an IPSD shall be clearly signed and have appropriate protection to include but not be limited to securing current transformers and system schematics at the main switchboard.