AS/NZS 4777: Solar inverter compliance in Australia

When you're comparing solar quotes, most of the conversation is about panel brand, kilowatts, and the rebate. The inverter usually gets a one-line mention. That's a mistake — the inverter is the part of the system that has to live with the grid, respond to it, and protect both your installation and the network on the other side of the meter.

The standard that defines what your solar inverter has to do, and how it has to be installed, is AS/NZS 4777. Every grid-connected rooftop PV system in Australia is bound by it, and every battery system that feeds back through an inverter (which is most of them) is bound by it as well.

This is a plain-English explanation of what AS/NZS 4777 covers, what changed with the 2020 revision, what a compliant inverter actually does on a hot Melbourne afternoon, and how to tell whether the inverter on your quote is the real deal.

What is AS/NZS 4777?

AS/NZS 4777 is the joint Australian/New Zealand standard for grid connection of energy systems via inverters. It's published by Standards Australia and adopted into law by state electrical safety regulators — in Victoria, that's Energy Safe Victoria (ESV), under the Electricity Safety Act 1998.

The standard is split into two parts that work together:

Part	Title	What it covers
AS/NZS 4777.1	Installation requirements	How the inverter is wired in: protection, isolation, labelling, anti-islanding behaviour, location, multiple-inverter coordination, and how the system interacts with the rest of your electrical installation. The job your installer has to get right.
AS/NZS 4777.2	Inverter requirements	What the inverter itself has to be capable of: voltage ride-through, frequency response, volt-watt and volt-var curves, demand response, harmonics, anti-islanding, power quality. The job the manufacturer has to get right and prove with type-testing.

So when an installer says a system "complies with AS/NZS 4777", they're really saying two things — the kit they've chosen complies with Part 2, and the way they've installed it complies with Part 1. Both have to hold for the Distribution Network Service Provider (DNSP) to allow the connection.

A third standard, AS/NZS 5033, sits next to AS/NZS 4777 and covers the DC side of the system — the array, the strings, isolators, DC cabling, and rooftop safety. We'll come back to it briefly at the end.

Why this matters to a homeowner

Three concrete reasons:

1. Your DNSP won't approve a non-compliant system

In Victoria, that's CitiPower, Powercor, Jemena, AusNet Services, or United Energy depending on where you live. The pre-approval process they run before letting you connect rooftop PV explicitly requires the inverter to be on the Clean Energy Council (CEC) approved inverter list — a list that, in turn, is gated on AS/NZS 4777.2 type-testing.

If the inverter on your quote isn't on that list, the system either doesn't get approved, or gets approved and then disconnected later when the network audits. Either way, you've paid for an installation you can't legally use.

2. STC rebates depend on it

The federal Small-scale Technology Certificate (STC) rebate — the discount baked into most solar quotes — is administered by the Clean Energy Regulator, but the eligibility rules require a CEC-accredited installer using CEC-listed equipment. Non-compliant inverter, no rebate, and you wear the difference.

3. The grid is getting tougher, not easier

Rooftop PV in Australia has gone from a curiosity to a genuine grid-management problem in some networks. The 2020 revision of AS/NZS 4777.2 was a direct response — it gave DNSPs new tools to manage voltage on hot, sunny, low-load afternoons when the grid is awash with solar exports. If your inverter pre-dates the 2020 revision and you're upgrading or extending, expect that to come up.

What changed in the 2020 revision

AS/NZS 4777.2:2020 replaced the 2015 edition and became mandatory for new connections from December 2021. Three changes matter to a homeowner:

Demand response modes (DRM 0 to DRM 8)

Inverters now have to support a defined set of Demand Response Modes — signals the network can send (typically through a separate device) to tell the inverter to back off, disconnect, or stay within certain limits. The full list:

• DRM 0: disconnect from grid (off, or a fault has been detected)
• DRM 1: do not consume power (relevant to bidirectional inverters and batteries)
• DRM 2: do not consume more than 50% of rated power
• DRM 3: do not consume more than 75% of rated power, with reactive-power capability
• DRM 4: increase power consumption (load-up signal, mostly for batteries)
• DRM 5: do not generate power
• DRM 6: do not generate more than 50% of rated power
• DRM 7: do not generate more than 75% of rated power, with reactive-power capability
• DRM 8: increase power generation

Most rooftop PV inverters won't ever see DRM 0, DRM 5, DRM 6, or DRM 7 in normal life — they're emergency tools the network can reach for during a system event. But the inverter has to be capable of them, and the installer has to wire the demand-response interface so the network can reach them if it ever needs to.

Volt-watt and volt-var response

This is the one that affects your daily life. AS/NZS 4777.2:2020 mandates grid-protective response curves that change the inverter's behaviour as voltage at the connection point drifts up or down:

• Volt-watt: when grid voltage climbs above a set threshold (typically 253 V and up), the inverter automatically reduces its export. At extreme high voltage, it curtails to zero. This is "volt-watt curtailment" and it's why your solar might be producing less than it should on a sunny, hot afternoon when half the street is also exporting.
• Volt-var: the inverter can absorb or supply reactive power to help stabilise voltage in the local area. You don't see this on your meter, but the network does.

Volt-watt response is a feature, not a fault. If your installer or salesperson presents curtailment as a defect, they're either misinformed or selling around the standard. The right response to chronic curtailment isn't "disable the curve" (you can't, legally) — it's a conversation about phase balancing, supply voltage at your connection, or whether a battery makes sense to soak up the production the grid won't take.

Type B RCDs in some cases

AS/NZS 4777.1:2016 was already strict about isolation and protection. The 2020 work, combined with updates to AS/NZS 3000, has tightened the rules around DC fault currents — particularly on systems where the inverter doesn't provide its own internal galvanic isolation. In those cases, the protection on the AC side may need to be a Type B RCD, which detects smooth DC residual currents that an ordinary Type A safety switch will miss.

Most modern transformer-less string inverters are designed to make this a non-issue — they include the necessary internal monitoring so the AC-side RCD can stay Type A. But if your installer mentions a Type B RCD on the quote, that's not them gold-plating, that's them following the standard for that specific inverter topology.

DRED — Demand Response Enabling Device

The DRED is the physical interface between the network's demand-response signal and your inverter — typically a small box near the meter or switchboard with a hard-wired link back to the inverter's DRM port. AS/NZS 4777 requires the inverter to expose this port; whether a DRED is actually fitted depends on the network's rules in your area at the time of connection.

In Victoria, expect a DRED-ready installation as a baseline. The DNSP may not be using it actively today, but the architecture has to be there.

How AS/NZS 4777 sits next to other standards

Solar compliance isn't one document. The full stack for a rooftop PV install is:

• AS/NZS 4777.1: how it's installed
• AS/NZS 4777.2: what the inverter must do
• AS/NZS 5033: the DC side — array layout, string design, isolators, rooftop labelling, fire-service shutdown
• AS/NZS 3000: the Wiring Rules, which govern the AC side from the inverter back to your switchboard
• AS/NZS 5139: if there's a battery, the safety-of-battery-systems standard takes over for the storage portion

AS/NZS 5033 is the one most homeowners haven't heard of, but it's the reason you'll see a DC isolator on the roof under the panels and another one near the inverter. It also drives the placard with the array's open-circuit voltage that has to be visible to a firefighter pulling up to your house at 3am — they need to know the array is still energised by daylight even after the main switch is off.

How to tell if a quoted inverter is compliant

You don't need to be an electrician to do this in five minutes. Three checks:

1. Find it on the CEC approved inverter list

The Clean Energy Council publishes a public list of inverters that have passed AS/NZS 4777.2 type-testing and are eligible for grid connection in Australia. Search the inverter brand and model number from the quote. If it's not on the list, that's the end of the conversation.

2. Check the version of AS/NZS 4777.2

The CEC list shows whether each inverter is approved against the 2020 revision (or the older 2015 revision, with an end-date). For a new connection in 2026, you want the 2020 revision. If the quote is for an inverter that's only approved against 2015, ask why — there are legitimate stock-clearance reasons, but you should at least know.

3. Check the installer is CEC-accredited

The standards govern the equipment and the install, but they don't govern who's allowed to do the install. That's the CEC Accredited Installer scheme, which sits on top of the base electrician's licence (in Victoria, an A-grade licence and a Registered Electrical Contractor (REC) — see our reference on CEC accreditation for the full picture).

A compliant inverter installed by a non-accredited person doesn't earn STCs, doesn't get DNSP approval, and creates an insurance and warranty mess. All three pieces — the kit, the install, and the installer — have to line up.

What to ask your installer

A few good questions to put on the table when you're comparing quotes:

• "Is this inverter approved against AS/NZS 4777.2:2020?"
• "Will the volt-watt curve be set to the default Australian region values, or are you applying region-specific settings?"
• "Will a DRED be fitted, or is the inverter being installed DRED-ready only?"
• "Has my DNSP pre-approval come back yet, and what export limit did they apply?"
• "Will I receive a Certificate of Electrical Safety (COES) for the AC-side work?"

You don't need to follow up the technical answers — you mostly want to know that the person quoting can answer. If the response is "don't worry about the 4777 stuff, it's all standard", that's not a wrong answer in spirit, but a good installer can also tell you which parts are standard and why.

How we handle it

Every grid-connect solar and battery installation we do at Millar Electrics goes through a simple compliance gate before the quote leaves our office: inverter on the current CEC list against AS/NZS 4777.2:2020, install designed to AS/NZS 4777.1 with AS/NZS 5033 on the DC side, AS/NZS 5139 layered on for any battery, AS/NZS 3000 for the AC tie-in, DNSP pre-approval lodged, COES issued and lodged with Energy Safe Victoria on completion.

It's not optional and it's not extra. It's how a compliant rooftop PV system gets to be one. We're a Victorian REC (REC-22849), based in Nunawading, serving the eastern suburbs and the wider metro area.

If you've got quotes in hand and want a second pair of eyes on the inverter spec, book a callback and we'll talk through them.