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AS 4777.1-2016 AS 4777.2-2015 AS 4777.3-2005
The AS 4777 Series — Grid Connection Made Compliant
The AS 4777 series is the regulatory gateway between your solar system and the electricity grid. Without compliance to these three standards, your network distributor will not approve the grid connection, and your system cannot legally export power.
AS 4777.1-2016 — Installation Requirements
Part 1 covers the physical installation of the grid connection — how the inverter is wired to the switchboard, how the metering enclosure is configured, and what documentation the installer must provide.
Inverter Location Requirements
Must be installed in a location that is accessible for inspection and maintenance
Minimum clearances: 300 mm above and below; 600 mm in front for access
Must not be installed in a bathroom, laundry, or other wet area
Outdoor installation requires inverter rated to appropriate IP rating (typically IP65 minimum) and installed to avoid direct western sun exposure where possible (heat reduces efficiency and lifespan)
Inverter display must be readable without a ladder — maximum height 1.8 m to the display centre
AC Connection to the Switchboard
The solar AC circuit must connect at the main switchboard, not at a sub-board (unless the sub-board is directly fed from the main board with adequate capacity)
A dedicated solar circuit breaker sized to the inverter AC output rating must be installed
For three-phase inverters: all three phases must be connected; single-phase connection of a three-phase inverter is not permitted
A solar generation meter or bidirectional meter (import/export) must be installed per the network distributor's requirements
Documentation — What the Installer Must Provide
Certificate of Compliance Electrical Work (CCEW) or equivalent state document
System commissioning form with measured VOC, ISC, and inverter operational checks
CEC Design and Installation Certificate signed by the CEC-accredited installer
Inverter model and serial number recorded (must match CEC approved products list)
As-built single-line diagram showing array configuration, inverter, isolation points, and metering
AS 4777.2-2015/R2017 — Inverter Requirements
Part 2 is the most technically complex standard in the series. It specifies the electrical performance requirements that inverters must meet before they can be used in Australian grid-connected solar systems.
Key Technical Requirements
Parameter | Requirement | Purpose |
|---|---|---|
Power quality — Total Harmonic Distortion | <5% THD at rated output | Prevents interference with grid power quality |
Power factor | 0.8 lagging to 0.8 leading (adjustable) | Required for Volt-VAR control (VVC) under DNSP requirements |
DC current injection | <0.5% of rated AC current | Prevents saturation of distribution transformers |
Anti-islanding response time | <2 seconds to cease export after island detection | Protects lineworkers from energised isolated sections |
Volt-Watt response | Mandatory in most states — inverter must reduce output when grid voltage is high | Manages voltage rise in low-voltage feeders with high solar penetration |
Volt-VAR response | Required in SA and some other states | Reactive power absorption to support grid voltage |
Frequency response (ROCOF) | Must trip within limits if rate-of-change-of-frequency exceeds threshold | Grid stability during large frequency transients |
The CEC Approved Products List
Only inverters that have been independently tested against AS 4777.2 and approved by the Clean Energy Council may be installed in grid-connected systems that receive the Small-scale Technology Certificate (STC) rebate. Using a non-approved inverter:
Voids the STC rebate for the entire installation
Will be refused connection by the network distributor
May void the building's electrical warranty
AS 4777.3-2005 — Grid Protection Requirements
Part 3 specifies the protection settings for inverters — the voltage and frequency thresholds at which the inverter must disconnect from the grid. These settings are configured at commissioning and must not be altered after installation without network distributor approval.
Parameter | Typical Setting (DNSP-dependent) |
|---|---|
Under-voltage trip (V<) | 0.87 pu (218V for 230V nominal) |
Over-voltage trip (V>) | 1.10 pu (253V for 230V nominal) |
Under-frequency trip (F<) | 47 Hz |
Over-frequency trip (F>) | 52 Hz |
Reconnection delay after trip | Minimum 60 seconds (DNSP may require longer) |
Anti-islanding method | Active frequency shift, slip-mode frequency shift, or equivalent |
Anti-Islanding is Non-Negotiable: If the grid fails and your inverter continues to supply power to the local network segment (islanding), it creates a live conductor for lineworkers who believe they are working on a de-energised system. This is why all grid-connected inverters in Australia must have an approved anti-islanding scheme — and why a compliant system must be tested at commissioning.
Engr. Jason Morales — Founder, SolarEnergyPH
