Adding a Battery to Existing Solar in Perth: Complete Retrofit Guide 2026
Over 400,000 WA homes already have rooftop solar. If you're one of them and watching your excess solar export for just 2.25c/kWh, adding a battery can capture that energy for evening use at 32c/kWh. Here's how to retrofit a battery onto your existing system.
Easiest retrofit option — works with any existing solar inverter. No rewiring needed.
Higher efficiency (~95% vs ~90%) but requires replacing your existing inverter with a hybrid model.
Replace your existing inverter with a hybrid inverter + battery. Best if your inverter is 5+ years old.
Your Three Options for Adding a Battery
Option 1: AC-Coupled Battery (Simplest Retrofit)
An AC-coupled battery connects to your home's electrical switchboard independently of your existing solar inverter. Your solar panels and inverter continue working exactly as they do now — the battery simply monitors your power flow and charges from excess solar or discharges when you need it.
- Pros: Works with any existing solar inverter, no rewiring of solar panels, simplest installation, minimal disruption
- Cons: Slightly lower efficiency (~90% round-trip due to double conversion: DC→AC→DC→AC), typically higher per-kWh cost for the battery unit
- Best batteries: Tesla Powerwall 3, Enphase IQ Battery 5P
- Installed cost: $10,000–$15,000 for 10–13.5 kWh
Option 2: DC-Coupled Battery (Replace Inverter)
A DC-coupled battery connects directly to your solar panels through a new hybrid inverter, bypassing the old inverter entirely. Solar energy is stored directly in DC form, avoiding conversion losses.
- Pros: Higher efficiency (~95% round-trip), typically lower per-kWh battery cost, single integrated system for monitoring
- Cons: Requires replacing your existing solar inverter ($2,000–$4,000 additional), some solar panel rewiring may be needed, longer installation time
- Best batteries: Sungrow SBR + SH hybrid inverter, BYD Battery-Box HVM + Fronius/GoodWe hybrid, Huawei LUNA 2000 + SUN2000 hybrid
- Installed cost: $9,000–$14,000 for 10–13 kWh (including new hybrid inverter)
Option 3: Hybrid Inverter Swap (Best if Inverter is Old)
If your existing solar inverter is approaching the end of its warranty (typically 5–10 years), replacing it with a hybrid inverter and adding a battery at the same time makes financial sense. You'd need a new inverter eventually anyway — doing it now means you only pay for one installation visit.
How to Determine Your Best Option
| Your Situation | Best Option | Why |
|---|---|---|
| Inverter under 3 years old | AC-coupled | Don't waste a nearly-new inverter |
| Inverter 3–7 years old, compatible brand | DC-coupled with compatible battery | Higher efficiency, keep existing inverter if hybrid-capable |
| Inverter 7+ years old | Hybrid inverter swap + DC battery | Replace ageing inverter and add battery in one visit |
| Micro-inverters (Enphase/AP Systems) | AC-coupled (Enphase IQ Battery) | Stays within the same ecosystem, no rewiring |
| Want backup power during blackouts | Either — check backup capability | Not all batteries provide backup; verify with installer |
Inverter Compatibility Check
Before getting quotes, check your current inverter brand and model. Here's what works with what:
- Fronius (Primo, Symo, Gen24): If you have a Gen24, it's already hybrid-ready — just add a BYD Battery-Box. Older Primo/Symo models need an AC-coupled battery or inverter replacement.
- Sungrow (SG series): Non-hybrid Sungrow inverters need replacing with an SH hybrid model to use Sungrow SBR batteries. Or add an AC-coupled battery instead.
- Huawei (SUN2000): Some SUN2000 models are hybrid-ready with the LUNA 2000 battery. Check your specific model number.
- GoodWe (DNS/SDT/MS): GoodWe hybrid models (ES/EM/ET series) work with the Lynx Home U battery. Non-hybrid models need replacing.
- Enphase micro-inverters: Use the Enphase IQ Battery for seamless AC-coupled integration within the Enphase ecosystem.
- Any other inverter: AC-coupled batteries (Tesla Powerwall 3, Enphase) work with any existing inverter.
Western Power Approval Process
Adding a battery to an existing solar system in Perth requires Western Power approval. Your installer handles this, but here's what's involved:
- A new Electrical Work Request (EWR) submitted by your electrician
- If your total inverter capacity changes (e.g., adding a hybrid inverter), a revised connection agreement may be required
- From May 2026, new installations must comply with updated SWIS connection requirements (AS/NZS 4777.2:2020 Australia Region B settings)
- Typical approval time: 2–4 weeks
Cost Comparison: Retrofit Options
10 kWh Battery Retrofit Costs (Before Rebates)
Battery + installation. Existing inverter untouched.
Battery + new hybrid inverter + installation + panel rewiring.
Battery + hybrid inverter. Best value since you needed a new inverter anyway.
Our Take
If your solar inverter is under 5 years old, an AC-coupled battery like the Tesla Powerwall 3 or Enphase IQ Battery is the simplest and most cost-effective retrofit. If your inverter is approaching end-of-life (7+ years), a hybrid inverter swap with a DC-coupled battery like Sungrow SBR delivers better long-term value. Take our battery quiz to find the best retrofit option for your specific setup.
Find Your Best Retrofit Option
Tell us about your existing solar system and we'll recommend the most cost-effective way to add a battery.
Published: March 8, 2026
Sources: SolarQuotes, Solar Choice, manufacturer compatibility guides, Western Power connection requirements. Prices are estimates for Perth metro. Data current as of March 2026.