The rules around solar and battery installations in Western Australia changed on 1 May 2026. If you are researching a new system — or wondering whether to add a battery to your existing solar — this post explains exactly where things stand today.
Quick Summary
From 1 May 2026, all new and upgraded solar and battery systems connected to WA’s South West Interconnected System (SWIS) must meet updated connection requirements set by Western Power and Energy Policy WA. The key changes:
- Inverter capacity is now capped at 15kW on single phase and 30kW on three phase — aggregate across your solar inverter, battery inverter, and any other inverter-based generation on site
- All new inverters must either support remote disconnection by your retailer via CSIP-AUS communications, or be export-limited to 1.5kW. For Synergy customers the standard pathway is CSIP-AUS: inverters 5kW and under connect via ESM (Emergency Solar Management). Inverters above 5kW connect via a fixed export limit determined at the point of connection. The 1.5kW cap is the alternative for systems without internet connectivity or remote management capability
- Inverters must comply with AS/NZS4777.2:2020 and be commissioned to the Australia Region B grid profile
- The federal Cheaper Home Batteries rebate is now tiered by capacity, not a flat rate per kWh
Systems installed and commissioned before 1 May 2026 are grandfathered. If your system pre-dates the change, it is not affected — until you upgrade or modify it.
The Inverter Limits: 15kW Single Phase, 30kW Three Phase
Under the new rules, the total inverter capacity on your site is capped at 15kW for single-phase connections and 30kW for three-phase connections. This is a whole-of-site aggregate — it covers your solar inverter, battery inverter, and any other inverter-based generation combined.
For most Perth homes this is more than enough. A typical 6.6kW to 13.2kW solar system paired with a mid-sized battery will sit well within the 15kW single-phase limit. The cap becomes relevant if you are planning a larger system — multiple battery stacks, a high-capacity EV charger, or a large solar array on a single-phase connection.
Three-phase homes have considerably more headroom, with the 30kW cap accommodating larger solar arrays and multiple battery stacks comfortably.
Export Pathways: How They Work and Which Applies to You
The export pathway that applies to your system depends on your inverter size. This is one of the more misunderstood aspects of the new rules.
ESM (Emergency Solar Management) — Inverters 5kW and Under
ESM applies to inverters at or below 5kW. It gives Western Power the ability to remotely disconnect and reconnect your solar export during a genuine grid emergency. In practice, ESM has been in place in WA for several years and has never been activated for a real event — only routine network testing has taken place.
This pathway requires internet connectivity and is required for full DEBS feed-in tariff access and Synergy Battery Rewards VPP eligibility.
Fixed Export Limit — Inverters Above 5kW
For inverters above 5kW, a fixed export limit applies rather than ESM. The specific limit is determined at the point of connection and reflects the capacity of the local network. This is the standard pathway for most solar and battery installations in Perth, given that the majority of systems now use inverters above 5kW.
The 1.5kW Cap — When It Applies
The 1.5kW export cap is the alternative for systems that are not configured for ESM and do not have a fixed export limit applied. It does not require internet connectivity and suits specific circumstances:
- Homes with unreliable internet connectivity, where ESM cannot function reliably
- Sites with multiple inverters from different brands, where achieving whole-of-site compliance across all equipment is technically complex or cost-prohibitive
- Homeowners who do not wish to participate in the VPP or have their export managed remotely
The 1.5kW cap does reduce the value of any excess solar sent to the grid. That means it is worth discussing with your installer which pathway applies to your setup.
How the Rebates Work Now
The federal Cheaper Home Batteries Program remains available in 2026, but the rebate structure has changed from a flat rate to a tiered system. The rate per kWh decreases as battery capacity increases:
- 0 to 14kWh: approximately $258 per kWh
- 14 to 28kWh: approximately $155 per kWh (60% of the full rate)
- 28 to 50kWh: approximately $39 per kWh (15% of the full rate)
For a typical 10kWh system, the federal rebate alone reduces upfront cost by approximately $2,580. Larger systems continue to attract rebate at each tier, but the marginal return decreases above 14kWh and again above 28kWh — which is worth factoring into your sizing decision.
Important: these rates reduce twice a year, every year, as the program steps down toward 2030. The sooner you install, the higher the rebate you access. If you are comparing quotes across a few months, check whether the rate has been updated.
The WA Residential Battery Scheme (state rebate) stacks on top. Synergy customers can access up to $1,300 additional rebate, provided the battery is on the Synergy Supported Solutions List (SSL) and connected to the Battery Rewards VPP.
Legacy Systems: The Pre-2018 Wiring Question
If you have an older solar system and are thinking about adding a battery, the new rules introduce additional complexity — particularly for systems installed before 2018.
Pre-2018 systems were wired to different standards and may not be straightforwardly compatible with the new export pathway and commissioning requirements. Bringing an older system into compliance can require rewiring, inverter replacement, or a fresh Synergy application — all of which add cost.
Here is the practical reality: most solar systems installed before 2018 came with 10- to 15-year warranties. Many of those warranties have now expired or are expiring. The panels, inverters, and wiring in those systems are approaching end of useful design life. In many cases, replacing the system outright — rather than patching and upgrading a decade-old installation — is the lower-cost and better long-term decision.
A full replacement gives you a modern inverter that meets the new standards, a new warranty period, access to the full rebate stack, and a clean Synergy application. It is worth getting a proper assessment before committing to a costly upgrade of an older system.
VPP and SSL Eligibility: What is Actually Compatible
To access the WA state rebate through the Battery Rewards VPP, your battery must be on Synergy’s Supported Solutions List (SSL). Within the Positive Energy Solutions range:
- SigEnergy SigenStor (DC-coupled): SSL-eligible, VPP-eligible
- Sungrow SBR and SBH: SSL-eligible, VPP-eligible
- iStore Battery: SSL-eligible, VPP-eligible
- Fronius GEN24 Reserva: SSL-eligible, VPP-eligible
- BYD Battery-Box HVM: SSL-eligible, VPP-eligible
- Tesla Powerwall 3: not on the SSL — not eligible for the WA state rebate or VPP
- SigEnergy (AC-coupled): not VPP-eligible under current network rules
If VPP access and the WA state rebate are priorities, DC-coupled SigEnergy or any of the other four brands are the right choice.
The Admin Reality: Synergy, Western Power, and Plenti
Installing a solar battery system in Perth in 2026 involves separate applications and compliance steps across multiple parties: Synergy (as your retailer), Western Power (as the network operator), and Plenti — who administers both the WA Residential Battery Scheme rebate and the no-interest loan.
The Plenti no-interest loan is available to eligible Synergy customers, subject to a maximum household income of $210,000 and VPP eligibility — meaning your battery must be on the SSL and connected to the Battery Rewards program. It cannot be accessed for Tesla Powerwall 3 or SigEnergy in AC-coupled configuration.
Each of these parties has its own requirements, timelines, and documentation. For homeowners managing this independently, the administrative burden is significant — and errors or missing information can delay installation by weeks.
Positive Energy Solutions manages the entire process. From the initial assessment through to Synergy, Western Power, and Plenti applications, commissioning, and VPP connection, our team handles every step. You should not need to contact any of them yourself.
Related guides
- Adding a Battery to Your Existing Solar System in Perth: 2026 Costs, Rebates, and Inverter Compatibility Guide
- Best Solar Batteries for Perth Homes in 2026
- Is LFP Battery Chemistry Right for Perth Homes? A Closer Look at the BYD Battery-Box Premium HVM
- DC-Coupled vs AC-Coupled Solar Batteries: What Perth Homeowners Need to Know
Frequently Asked Questions
Can I still access the rebate if I install now?
Yes. Both the federal Cheaper Home Batteries Program and the WA Residential Battery Scheme are open. The federal rebate is now tiered by capacity rather than a flat rate per kWh, and it steps down twice a year. Synergy customers with an SSL-eligible battery can access both rebates simultaneously.
What does the 1.5kW export cap actually mean in practice?
Any solar generation your home cannot use is capped at 1.5kW before it reaches the grid. On a sunny afternoon, your system will still power your home fully — the cap only affects what you can export. For homes with batteries, most of that excess solar would be stored anyway, so the practical impact varies by usage pattern.
My solar system is 10 years old. Do I need to replace it to add a battery?
Not necessarily, but it depends on your existing system. Inverters installed before 2018 may not be compatible with the new commissioning requirements or the applicable export pathway. In some cases the cost of bringing an older system into compliance exceeds the cost of a fresh installation with a new warranty. We assess this on a system-by-system basis.
Does ESM mean Synergy or Western Power can turn off my solar whenever they want?
No. ESM applies to inverters 5kW and under and is a network emergency function only. It has been in place in WA for several years without a single real activation — only routine network testing has occurred. Your system operates normally the vast majority of the time.
Which batteries in the Positive Energy Solutions range are VPP-eligible?
SigEnergy (DC-coupled), Sungrow, iStore, Fronius Reserva, and BYD are all on the SSL and are VPP-eligible. Tesla Powerwall 3 is not on the SSL. SigEnergy in AC-coupled configuration is not VPP-eligible under current network rules.
Is the no-interest loan still available?
Yes, for eligible customers. Plenti administers both the WA state rebate and the no-interest loan. The loan is available to Synergy customers with a household income up to $210,000, provided their battery is VPP-eligible. Positive Energy Solutions manages the Plenti application as part of the installation process.
About the Author
Jason Wiktorowicz
Sales Manager, Positive Energy Solutions | Perth, WA
Jason has been at the centre of Western Australia’s energy transition for over a decade. As Orchestration Lead on Project Symphony — WA’s largest virtual power plant pilot — and Stream Lead on Project Encore, he worked directly with AEMO, Western Power and Energy Policy WA to shape how distributed energy resources connect and operate on the SWIS. That work included developing and rolling out CSIP-AUS, now mandatory for all new WA grid connections. He also led Emergency Solar Management (ESM), the first program of its kind in WA, VPP for Schools (VPP4S), which provided direct market benefits through Supplementary Reserve Capacity, and REBAR, the WA Residential Battery Rebate scheme.
His earlier career spanned Synergy, Infinite Energy and Curtin University’s Sustainability Policy Institute, where he co-authored peer-reviewed research on net-zero urban precincts, solar integration and peer-to-peer energy trading, published in the journal Urban Planning in 2018.
At Positive Energy Solutions, Jason leads sales with a focus on system design accuracy and long-term performance. Positive Energy Solutions installs solar and battery systems, EV chargers and heat pumps, and holds partner accreditations with Fronius, SigEnergy, iStore and SunPower. Connect with him on LinkedIn.
