Solar and Battery Installations in WA: What’s Changing on 1 May 2026

From 1 May 2026, Western Power is introducing updated technical requirements for new and upgraded solar PV systems, battery energy storage systems, and other inverter-based technologies connected to the South West Interconnected System (SWIS).These changes apply to all installations and modifications commissioned on or after 1 May 2026. Systems already commissioned before this date will continue under the existing rules and are not affected.Increased Inverter Capacity LimitsOne of the most notable updates is the significant increase in allowable inverter capacity. Households and small businesses on a standard connection can now install up to 30 kVA of total inverter capacity. This includes rooftop solar, batteries, and any other inverter-connected systems combined.This change particularly benefits single-phase properties, allowing substantially larger solar and battery setups than were previously permitted under the old limits.New Technical and Compliance RequirementsAll new and upgraded systems must be installed and commissioned according to the latest Australian Standard AS/NZS 4777.2:2020 with “Australia Region B” settings. In addition, systems are now required to support Emergency Solar Management (ESM) functionality. This allows the network or retailer to remotely manage the system during specific grid events.Installations have two primary compliance pathways:

• Responsive Mode — Full ESM capability, enabling flexible or dynamic export limits when grid conditions permit.
• Restricted Mode — Limited to a fixed export limit (typically 1.5 kW) for systems that do not support remote management.

These requirements are assessed on a whole-of-site basis, meaning every inverter on the property must meet the new standards.

Purpose Behind the Changes

Western Power’s updates are designed to safely accommodate the continued rapid growth of rooftop solar and battery installations across the SWIS. As more households generate their own power, the ability to manage inverter output during periods of high solar generation or grid stress helps maintain overall network stability and reliability. The inclusion of Emergency Solar Management also supports the future development of services such as Virtual Power Plants (VPPs).

What This Means for Applications

The new rules introduce additional technical documentation and verification steps during the Western Power connection application process. Inverters and batteries must be compatible with the updated standards, and proper commissioning is essential for approval. The changes apply specifically to the timing of commissioning rather than the date of application.

Relationship to Rebates and Incentives

These technical connection requirements are separate from federal Small-scale Technology Certificates (STCs) and the WA Residential Battery Scheme. However, the focus on systems capable of supporting grid services aligns with broader state and federal policies that increasingly encourage battery participation in Virtual Power Plant programs.

Summary

From 1 May 2026, Western Power’s updated connection rules will allow significantly larger solar and battery systems (up to 30 kVA total inverter capacity) while introducing mandatory Emergency Solar Management capability and whole-of-site compliance. The changes reflect the network’s efforts to manage high levels of distributed energy resources while enabling households to install more substantial renewable energy systems. Anyone planning a new solar or battery installation, or an upgrade to an existing system, should be aware of these upcoming requirements and their impact on system design and approval processes.