If you already have solar in Perth, adding a battery to your existing solar system is one of the most financially compelling upgrades you can make in 2026. Synergy’s DEBS scheme pays just 2c/kWh for solar exported outside the 3pm–9pm peak window — and most households are exporting the majority of their midday generation at that rate. A battery captures that surplus instead, storing it for evening use when grid electricity costs 33.26c/kWh. That is a 30c/kWh swing in value for every kilowatt-hour your battery captures.
In 2026, with a stacked federal and WA state rebate, a no-interest loan through Plenti, and updated WA export rules that make batteries essential for larger inverter systems, the timing has never been better. But before looking at inverter compatibility and rebates, there is a more fundamental question worth answering first.
Older Systems: When a Full Replacement Makes More Sense
If your solar system was installed before 2018, it is worth having an honest conversation about what makes financial sense before committing to a battery retrofit.
Inverters from that era are now eight years old or more — at or beyond their typical warranty period. Panel output has degraded over time. And many of the solar installers who put these systems in are no longer in business, leaving homeowners with no support or warranty recourse if something goes wrong.
When you weigh up the cost of replacing the inverter with a hybrid plus adding a battery, a full system replacement — new panels, new hybrid inverter, and battery together — is typically lower-cost and more practical. You start fresh with current technology, a full new warranty, a reputable installer behind you for the long term, and a system correctly sized for today’s household usage and WA’s updated export rules.
We always recommend homeowners with older systems get a full assessment before assuming a retrofit is the right path. In most cases, the numbers — and the long-term peace of mind — favour starting fresh.
Which Path Is Right for You? A Quick Reference
For systems where a retrofit makes sense, the right approach depends on what you already have. Use this as a starting point — your energy consultant will confirm the best path during the site assessment.
The Three Retrofit Paths in Detail
Path 1: You Already Have a Hybrid Inverter
Hybrid inverters — such as the Fronius GEN24 PLUS, Sungrow RS or RT series, or iStore hybrid units — are designed to connect a battery directly on the DC side. If you already have one, adding a battery is the simplest retrofit available. Your installer connects a compatible DC-coupled battery to the existing hybrid inverter, commissions it, and the system operates as a single integrated unit. No inverter replacement required.
Path 2: You Have a Standard String Inverter
Standard string inverters were not designed to connect a battery directly. The recommended approach is to replace the existing string inverter with a hybrid inverter and add a DC-coupled battery at the same time — giving you the same efficient, integrated outcome as Path 1, with an inverter swap as part of the process.
Path 3: You Have an Enphase or Microinverter System
Microinverter systems — where each solar panel has its own small inverter — cannot have a hybrid inverter retrofitted in the same way as a string system. For these systems, an AC-coupled battery is the appropriate solution. The battery connects on the AC side of the system, independent of the microinverters, and charges from the household’s AC supply.
AC-coupled systems work well but come with important WA compliance considerations. AC-coupled configurations must meet whole-of-site compliance requirements set by Western Power, and not all AC-coupled battery options are straightforward under the current framework. This affects both VPP eligibility and connection approval. For a detailed technical breakdown, see our DC-Coupled vs AC-Coupled Solar Batteries guide.
Inverter Size, Export Limits, and DEBS: What You Need to Know
Under WA’s current connection rules, inverter size has a direct impact on both your export entitlements and your access to the DEBS feed-in tariff.
For inverters above 5kW — which includes the majority of systems installed during Perth’s solar growth period — there is no DEBS feed-in tariff. Generation above the fixed export limit is curtailed and goes nowhere. This means households with larger inverters are already receiving no feed-in payment and losing curtailed generation every single day.
A battery changes this entirely. Instead of generation being curtailed or sent to the grid for nothing, your battery captures it and stores it for evening use at 33.26c/kWh value. For households with inverters above 5kW, a battery is the only way to get value from the generation your system is currently losing.
For inverters at or below 5kW, DEBS applies and a battery does not affect your eligibility. The battery simply redirects generation that would have been exported at the off-peak 2c/kWh rate into storage — a significantly better outcome.
Battery Clearance Zones and Installation Requirements
Battery placement is governed by Australian Standard AS/NZS 5139, which sets mandatory requirements for where a battery can and cannot be installed on your property. Getting this right is not optional — non-compliant installations can affect your warranty, insurance, and network connection approval.
Batteries must not be installed in habitable rooms, including bedrooms, living rooms, and studies. Common approved locations include the garage or a suitable external wall. The specific requirements vary with the battery model, the construction of your home, and the clearances available from windows, doors, vents and other openings.
Clearance requirements are not one-size-fits-all. Each battery has manufacturer-specified clearances that must be met, and some installations require additional work such as fire-rated wall lining before the battery can be mounted.
Speak to your Positive Energy Solutions energy consultant during the assessment stage. We will identify the most suitable and compliant installation location for your property and advise on any preparatory work required before installation day.
The Rebate Stack for Existing Solar Customers
Having solar already in place means you satisfy the solar requirement for both the federal and WA state rebates immediately. In 2026, eligible Perth homeowners can access three layers of financial support.
The Federal Cheaper Home Batteries Program
The federal rebate is tiered by battery capacity:
- 0 to 14kWh: approximately $258 per kWh
- 14 to 28kWh: approximately $155 per kWh
- 28 to 50kWh: approximately $39 per kWh
These rates reduce twice per year. The sooner you act, the higher the rebate you lock in.
The WA Residential Battery Scheme
Synergy customers who install an SSL-eligible battery and enrol in the Battery Rewards VPP receive an additional $1,300 state rebate, administered through Plenti. This stacks directly on top of the federal rebate.
The Plenti Interest-Free Loan
Eligible Synergy customers can access up to $10,000 no-interest over 3 to 10 years through Plenti. For many households, monthly electricity savings exceed the monthly loan repayment from day one — making the battery cash-flow positive from the start.
Positive Energy Solutions manages all rebate and loan applications on your behalf as part of the installation process.
Battery Retrofit Costs in Perth: Estimated Pricing After Rebates
The table below shows estimated installed costs for common battery sizes in Perth after all available rebates are applied. Figures will be updated with current Positive Energy Solutions pricing.
* Prices after federal Cheaper Home Batteries Program and WA Residential Battery Scheme ($1,300 for eligible Synergy customers). Payback based on Synergy A1 tariff (33.26c/kWh import). Speak to your energy consultant for a personalised quote.
VPP Eligibility: Which Batteries Work for Battery Rewards on a Retrofit
To access the $1,300 WA state rebate and Battery Rewards VPP activation credits, your battery must be on Synergy’s Supported Solutions List (SSL). Battery selection needs to account for this from the start.
- Tesla Powerwall 3 is not on the SSL and is not eligible for Battery Rewards or the WA state rebate.
- SigEnergy AC-coupled configurations are not eligible due to whole-of-site compliance requirements.
- SigEnergy DC-coupled systems are fully eligible.
- Sungrow SBR/SBH, BYD Battery-Box, and Fronius GEN24 Reserva are all eligible when installed correctly.
We only recommend SSL-eligible batteries to customers who want to access Battery Rewards and the WA state rebate, and we advise on the right option for your specific system configuration.
The Admin Burden — and Why We Handle It for You
Adding a battery to an existing solar system involves more than just the hardware. The approval and paperwork process carries a significant administrative burden:
- Western Power connection application and approval
- Synergy Battery Rewards enrolment
- Plenti rebate processing and loan application
- Coordination between all three parties throughout the process
Positive Energy Solutions manages the entire process from initial assessment through to a commissioned, operational system. We deal with Western Power, Synergy, and Plenti on your behalf. Our customers do not chase paperwork or navigate bureaucracy — we do all of that for them, from the first call to the final sign-off.
Get a Battery Assessment for Your Existing System
Every property is different — inverter type, system age, available installation locations, and usage profile all factor into the right solution. The starting point is a proper assessment.
Our energy consultants will review your existing system, your bills, and your property before making any recommendation. No generic advice — just a clear picture of your options and the numbers behind them.
Related guides
- How Much Can You Save with Solar and Battery in Perth? 2026 Breakdown
- How to Maximise Your Solar and Battery Savings in Perth
- Parker Lane Green Loan Perth 2026: Solar and Battery Finance When the WA Scheme Doesn't Apply
- Solar Battery Finance Perth 2026: WA Scheme, Plenti and Parker Lane Explained
Frequently Asked Questions
Can I add a battery to my existing solar system without replacing the inverter?
If you already have a hybrid inverter (such as a Fronius GEN24 PLUS, Sungrow RS or RT series, or iStore), yes. A DC-coupled battery connects directly to it. If you have a standard string inverter, the recommended approach is to replace it with a hybrid and add a DC-coupled battery at the same time. If you have an Enphase or microinverter system, an AC-coupled battery is the appropriate solution.
My system is older — should I replace it instead of retrofitting?
If your system is pre-2018, a full replacement — new panels, new hybrid inverter, and battery together — is typically lower-cost and more practical than retrofitting. Inverters from that era are at or past their warranty life, many original installers are no longer in business, and panel output has degraded. We can assess your system and give you an honest comparison of both paths.
Do I need a switchboard upgrade to add a battery?
Not always — it depends on your existing switchboard’s condition and capacity. Your energy consultant will assess this during the site visit and advise whether an upgrade is required as part of your installation.
Where can a battery be installed on my property?
Batteries cannot be installed in habitable rooms and must comply with AS/NZS 5139. The garage is the most common compliant location. Other locations depend on your specific property and battery model. Speak to your energy consultant — we assess compliance as part of every installation.
Which batteries qualify for Battery Rewards VPP on a retrofit?
Eligible options include SigEnergy DC-coupled, Sungrow SBR/SBH, BYD Battery-Box, and Fronius GEN24 Reserva. Tesla Powerwall 3 and SigEnergy AC-coupled are not eligible. We only recommend SSL-eligible batteries to customers who want to access Battery Rewards and the WA state rebate.
How long does the retrofit process take from quote to installation?
From initial quote to a commissioned system — including Western Power approval and rebate paperwork — is typically 4 to 8 weeks. The physical installation is usually completed in a day, though this may vary if a full system replacement is involved.
Will adding a battery affect my DEBS feed-in tariff?
It depends on your inverter size. If your inverter is 5kW or below, DEBS applies and adding a battery does not affect your eligibility. The battery simply captures generation that would have been exported at 2c/kWh and stores it for higher-value evening use. If your inverter is above 5kW, DEBS does not apply at all. You are already receiving no feed-in tariff, and any generation above the export limit is currently curtailed and lost. A battery recovers that value entirely.
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.
