The solar industry has seen massive growth over the past decade, and with it, new challenges in system design, safety, and installation practices. To address these evolving needs, the AS/NZS 5033 standard—governing the installation and safety of photovoltaic (PV) arrays—was significantly updated in late 2021.

The latest edition, AS/NZS 5033:2021, supersedes the standard of 2014 (its 2018 amendments included), with more succinct, adaptable, and forward-looking regulations. Whatever your role — PV installer, designer, or electrical contractor — these updates are likely to affect your business. Here’s why.

📅 Transition Period and Applicability

AS/NZS 5033:2021 became the new standard in November 2021. But a six-month transition period might apply to you, depending on your state or territory. For six months, you can use either the 2014 or 2021 version—but not both. Always consult your local electrical regulator before implementing the new rules.

🛠️ Why Was the Standard Updated?

The solar industry has changed significantly since 2014. Systems are more efficient, technologies such as DC optimisers and bifacial panels are mainstream, and there are heightened safety expectations. The 2021 revision captures these advances with the objective of:

• – Improve clarity and layout
• – Address emerging safety risks
• – Support a broader range of system sizes and designs
• – Standardise terminology

Let’s take a look at the most significant updates impacting system designers and installers.

📈 1. Expanded Scope of the Standard

The revised standard now covers a wider array of systems:

• Larger systems: The 240 kW upper limit has been removed. Designers working on commercial PV systems above this size must now follow the full requirements of AS/NZS 5033.
• Smaller systems: The lower scope now excludes arrays under 100 W and below 35 V open-circuit, regardless of whether the system is portable.
• Transportable and mobile PV systems: Systems on campervans, boats, demountables, and mobile signs are now excluded from AS/NZS 5033 and should instead comply with AS/NZS 3001 (transportables) or AS/NZS 3004 (boats).

⚡ 2. Increased Maximum System Voltage

Voltage restrictions have been a long-time limitation in residential PV design. The 2021 revision introduces quite profound changes:

• Domestic systems: The theoretical voltage limit has increased from 600 V DC to 1,000 V DC.
• Commercial/industrial systems: A new upper limit of 1,500 V DC now applies.
• Terminology update: “Domestic dwelling” has been replaced with “domestic electrical installation,” broadening applicability.

But there’s a twist. AS/NZS 4777.1:2016 continues to restrict domestic inverter-connected systems to 600 V. Until the standard is revised, residential systems will need to stay under the old voltage ceiling.

And don’t forget to include coldest site temperature when calculating maximum voltage.

🔢 3. Revised Current Calculations

AS/NZS 5033:2021 restructures the calculation of string current, fault current, and overcurrent protection as follows:

• Maximum string current is now clearly defined and used for cable sizing and protection.
• Fault currents from strings or sub-arrays must be calculated based on system design.
• Backfeed current (IBF TOTAL) from inverters or controllers must be considered when sizing protection devices.

Appendix J introduces the KI adjustment factor for bifacial modules to account for rear-side generation.

🚫 4. Changes to DC Rooftop Isolator Requirements

DC isolators have been a point of failure where they were typically required. Here are more open-ended alternatives introduced in this revision:

• Rooftop isolators are no longer mandatory in all cases.
• Disconnection points can be used instead—if labelling and safety rules are followed.
• Additional conditions apply if you omit isolators, including stricter signage and location rules.

For systems with microinverters or optimisers near panels (within 1.5 m and below 120 V input), isolators are still not necessary.

🔌 5. Introduction of “Disconnection Points”

The definition of “disconnection point” is new and describes a non-load-breaking connector (such as a plug-and-socket) that can safely disconnect a PV module or string.

Requirements include:

• Labelling: Must be marked with “WARNING: PV String Disconnection Point” within 300 mm.
• Accessibility: Must be easy to reach for maintenance and emergency access.
• Connector type: Only approved plug types are allowed.

This simplifies design and saves cost by eliminating the need for inessential rooftop isolators.

📋 6. Other Key Changes

The following are some other important changes:

• Cable routing: Improved guidance for ceiling spaces and mechanical protection.
• Signage and documentation: New layout plans, warning labels, and emergency fire signs are required.
• Helpful appendices: Diagrams and worked examples make the rules easier to follow.

AS/NZS 5033:2021 is a comprehensive revamp with emphasis on flexibility, safety, and clarity. Highlights include greater options for higher voltage, more simplified isolator specifications, and better documentation rules. But with them comes greater requirement for more accurate calculations and systems design.

Next steps for installers and designers:

• ✅ Review the full 2021 standard—especially Clauses 3, 4, and 5.
• ✅ Check with your local regulator about transition timing.
• ✅ Update your templates, labels, and string calculations.
• ✅ Speak with suppliers about component ratings and disconnection options.