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"Can I just add a battery later?"
It is the single most common question we get from homeowners who already have solar panels. And the short answer is yes. But the longer answer is: it depends entirely on what inverter you have sitting on your wall right now.
Get this decision right and you end up with a clean, efficient system that slashes your power bill and keeps the lights on during blackouts. Get it wrong and you are paying for equipment twice, running two apps, and losing energy at every step.
This guide walks through everything: what your options actually are, the difference between AC and DC coupling (in plain English), which brands are worth looking at in Australia right now, and the single biggest mistake homeowners make when retrofitting a battery.
Why your solar is probably underperforming without a battery
Here is a stat that surprises most solar owners: without a battery, the average household only uses about 30-40% of the solar they generate. The rest gets exported to the grid.
Real-world monitoring data consistently shows this pattern. One homeowner tracked their system meticulously and found only 36% of their solar was actually self-consumed. The other 64% was shipped off to the grid at whatever feed-in rate their retailer felt like paying.
And the maths on that are brutal. Your panels generate power worth 30-40 cents per kWh (what you would have paid the grid). But when you export it, you get 3-8 cents in feed-in tariff payments. You are selling your electricity at wholesale rates and buying it back at retail.
Without a battery vs with a battery
Self-consumption without battery
Typical Aussie household with 6.6kW solar
Self-consumption with battery
Same household with 10kWh battery added
Additional annual savings
By using stored solar instead of grid power in the evening
A battery lets you store that surplus solar and use it yourself in the evening and overnight, when your panels are not producing but your household is still drawing power. Instead of buying from the grid at peak rates, you drain the battery. The impact on your bill can be dramatic, as our guide to battery arbitrage explains in detail.
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AC coupling vs DC coupling: The decision that changes everything
This is the most important thing to understand when adding a battery to an existing solar system. There are two fundamentally different ways to do it, and the right choice depends on what equipment you already have.
AC Coupling
Keep your existing inverter, add a separate battery inverter
Your existing solar inverter stays where it is. A separate battery inverter (like a Tesla Powerwall 3, Sungrow SH series, or Enphase IQ) gets installed alongside it. The battery charges from AC power after your existing inverter has already converted it from DC.
DC Coupling
RecommendedReplace your inverter with a hybrid, connect battery directly
Your old inverter gets removed. A new hybrid inverter takes over everything: existing panels, new panels (if adding), and the battery. Solar power goes straight to the battery in DC form, with only one conversion to AC when it powers your home. One brain running the whole show.
For most Australian homeowners adding a battery to an existing system, DC coupling with a new hybrid inverter is the better long-term choice. Yes, you lose the old inverter. But you gain a system that works as a single, coordinated unit rather than two separate systems awkwardly trying to cooperate. Our two-kitchen mistake article breaks this down in more detail.
The exception: if you have microinverters (like Enphase) on every panel, AC coupling is your only realistic option. And that is fine. Products like the Enphase IQ Battery or Tesla Powerwall 3 are designed specifically for this scenario and they work well.
Step one: Check what inverter you have
Before you do anything else, go look at the box on your wall (or in your garage, or wherever your installer put it). The type of inverter you have dictates your entire path forward.
Standard grid-tie inverter (e.g., Fronius Primo, SMA Sunny Boy, older Sungrow)
This is the most common type. It converts DC from your panels to AC for your home and the grid. It has no battery connection. You will need to either add a separate battery inverter (AC coupling) or replace this with a hybrid (DC coupling).
Hybrid / battery-ready inverter (e.g., Sungrow SH series, Huawei SUN2000, GoodWe ET)
You are in luck. These have a built-in battery connection. Adding a compatible battery is relatively straightforward. Your installer connects the battery to the inverter, updates firmware, and you are away.
Microinverters (e.g., Enphase, AP Systems)
Each panel has its own tiny inverter. There is no central inverter to replace. AC coupling is the way to go. The Enphase IQ Battery is designed for this, or you can use a Tesla Powerwall 3 or FranklinWH aPower which AC-couple with anything.
Optimised inverter (e.g., SolarEdge with optimisers)
SolarEdge systems use panel-level optimisers, which means you cannot simply rewire the panels into a different inverter brand without either replacing the optimisers or using specialised adapters. Your options: wait for a DC-coupled SolarEdge battery solution, or AC-couple a separate battery system alongside it.
Battery and inverter options popular in Australia right now
The Australian battery market has exploded in the last couple of years. Here is a snapshot of what is being installed and discussed most in the Aussie solar community.
Sungrow SH + SBR Series
DC-coupled hybrid system
The Sungrow SH hybrid inverter paired with SBR modular batteries is one of the most popular retrofit combinations in Australia. The SH series ranges from 5kW to 10kW, and the SBR batteries stack from 3.2kWh up to 25.6kWh. Great value, solid reliability, and good local support. If you are replacing a standard inverter, this is often the go-to recommendation.
Tesla Powerwall 3
AC-coupled or integrated
The Powerwall 3 has a built-in inverter, so it can AC-couple with virtually any existing solar system. 13.5kWh capacity per unit, stackable up to 4 units. Excellent app, seamless backup, and it integrates with Tesla EV chargers. The downside: availability in Australia can be patchy and it is at the higher end of pricing.
Huawei SUN2000 + LUNA2000
DC-coupled hybrid system
Huawei's LUNA2000 battery pairs with their SUN2000 hybrid inverter. Modular design, competitive pricing, and excellent monitoring through the FusionSolar app. Worth noting: some owners have reported occasional firmware quirks where the battery shows full charge but does not discharge to home loads properly. Make sure your installer keeps firmware up to date.
Sigenergy
All-in-one DC-coupled system
Sigenergy is gaining serious traction in Australia. Their EC hybrid inverters range from 5kW up to 29.9kW (3-phase), and they pair with modular 8kWh battery units. The whole system is designed as one ecosystem including EV charger integration. A strong option if you are consolidating your old system into a new hybrid setup.
Enphase IQ Battery
AC-coupled, designed for microinverter systems
If you already have Enphase microinverters, the IQ Battery is the natural pairing. It integrates seamlessly into the Enphase ecosystem with everything visible in one app. Modular 5kWh units. The trade-off: it is AC-coupled by nature, so you accept the efficiency hit. But for microinverter homes, it is the cleanest solution.
FranklinWH aPower2
AC-coupled whole-home management
FranklinWH takes a different approach. Their aGate controller sits between your solar, battery, and home, managing energy flows regardless of your existing inverter brand. The aPower2 battery comes in 13.6kWh units. It is AC-coupled but designed to be a comprehensive whole-home energy management system. Well-regarded in online communities for its seamless backup capability.
For a deeper dive on specific battery models, pricing, and specs, check our battery comparison page and battery cost guide.
Real-world scenario: What this looks like in practice
To make this concrete, here is a typical scenario we see all the time.
A homeowner with an existing 5.7kW solar system and a SolarEdge inverter wants to add a battery and more panels. They are extending their house, adding air conditioning, and their power bills are climbing. They get two quotes:
Quote A: AC-coupled approach
Keep the existing SolarEdge inverter. Add a Sungrow SH6.0RS hybrid inverter with 16kWh SBR battery and 8kW of new panels. The Sungrow system runs independently alongside the SolarEdge. Two apps. The Sungrow's CT clamp monitors overall home energy to decide when to charge the battery from grid surplus, but it cannot directly communicate with the SolarEdge.
Quote B: Consolidated approach
Replace the SolarEdge entirely. Install a Sigenergy EC 10kW hybrid inverter with 2x 8kWh batteries (16kWh total) and 10kW of new panels. All existing panels rewired to the new inverter. One system, one app, DC-coupled. Higher upfront cost because you are replacing the SolarEdge, but better long-term efficiency and a much simpler system to live with.
The complication with this specific example: SolarEdge uses panel-level power optimisers, which means you cannot simply rewire those panels into a different brand of inverter without either replacing the optimisers or using specialised adapters. This is where the SolarEdge lock-in becomes a real factor and why some homeowners end up going AC-coupled even when DC-coupled would normally be the better choice.
The key concerns homeowners in this situation raise: which inverter becomes the "main" controller during a blackout? Will backup actually work? Can I see everything in one place? These are legitimate questions and they should be part of every conversation with your installer.
The biggest mistake: Buying a standard inverter when you should have gone hybrid
This is the single most common regret we hear from solar owners in Australia, and it comes down to one piece of advice: do not pay for the same equipment twice.
If you are getting solar installed for the first time and there is any chance you might want a battery in the future (and there is, because battery prices keep dropping), get a hybrid inverter from day one.
The price difference between a standard grid-tie inverter and a hybrid inverter is typically $500-$1,500. The cost of replacing a standard inverter with a hybrid later? $2,000-$4,000 for the inverter alone, plus installation labour, plus the waste of a perfectly functional piece of equipment.
The maths that matters
Installing a standard inverter now and replacing it with a hybrid in 3-5 years costs you roughly $2,500-$4,000 more than just getting the hybrid upfront. You are literally paying for two inverters when you could have paid for one. If you are getting solar installed today, this is the single most important decision you will make.
The hybrid inverter sits there, running your solar panels exactly the same as a standard inverter would, until the day you are ready to plug in a battery. Then it is a straightforward addition rather than a full system overhaul.
If you already have a standard inverter, do not panic. The options above (AC coupling or hybrid replacement) work well. But if you are reading this before your first install, consider this your heads-up.
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What to ask your installer before signing anything
Not all installers think about battery retrofits the same way. Some will default to the quickest option (bolt on an AC-coupled unit and move on). Others will take the time to assess whether DC coupling makes more sense for your situation. Here are the questions that separate the two.
Is AC coupling or DC coupling better for my specific setup, and why?
If DC coupling, what happens to my existing inverter? Is it still under warranty?
Will I have one monitoring app or two? Can I see all energy flows in one place?
How does backup work during a grid outage? Which inverter controls the switchover?
What is the total round-trip efficiency of the proposed battery setup?
What are my DNSP export limits, and how does the system handle them?
Can I add more battery capacity later if I need to?
Pro tip: Get at least 3 quotes
The answers to these questions will vary dramatically between installers. Some will only offer AC coupling because it is easier. Others will push DC coupling because they sell a particular brand. The best installers will explain the trade-offs for your specific situation and let you decide. Check installer reviews before committing.
Bonus: Your battery can earn money while you sleep
Once you have got a battery installed, you unlock something that solar panels alone cannot do: Virtual Power Plant (VPP) programs.
Instead of your battery just storing solar for your own use, VPP programs let your battery export stored energy back to the grid during high-demand events. Retailers pay you a premium for this, typically 15-25 cents per kWh and sometimes over $1/kWh during extreme demand. That is 3-5 times more than a standard feed-in tariff.
Most battery brands supported in Australia (Tesla, Sungrow, Enphase, Sigenergy) are compatible with one or more VPP programs. It is free additional income from hardware you already own. Check our VPP guide for program details and eligibility.
The quick decision framework
Here is the shortest version of this entire guide.
You have a hybrid inverter already
Add a compatible battery. Simple job. DC-coupled.
You have a standard inverter and it is out of warranty
Replace it with a hybrid and DC-couple the battery. One system, maximum efficiency.
You have a standard inverter still under warranty
Weigh up AC coupling now (keep the warranty value) vs DC coupling (better long-term). Crunch the numbers with your installer.
You have microinverters (Enphase, etc.)
AC coupling is your path. Look at Enphase IQ Battery, Tesla Powerwall 3, or FranklinWH.
You have SolarEdge with optimisers
AC coupling is usually the practical choice. Consider whether to wait for SolarEdge DC battery solutions or go with a third-party AC-coupled battery.
You have not installed solar yet
Get a hybrid inverter from day one. No exceptions. Do not pay for the same equipment twice.
The bottom line
Adding a battery to your existing solar is one of the smartest energy upgrades you can make. If you are still weighing up whether it is worth the investment, the answer for most households is a clear yes. You are already generating the power. Right now most of it is leaving your house and coming back at 5x the price. A battery changes that equation completely.
The key is getting the coupling method right for your situation and installing the battery somewhere it will not overheat. Australian heat can seriously shorten battery lifespan, so installation location matters. If you can DC-couple, do it. If AC coupling is the only option, that is still a massive improvement over no battery at all.
And if you have not installed solar yet? You know what to do. Hybrid inverter. Day one. No exceptions.
The next step
If you have any questions about the information in this guide, feel free to get in touch:
Email: hello@whysolar.com.au
Tel: +61 455 221 921
If you're considering a home battery system, Kim and the team can help you get quotes from trusted, pre-vetted local installers:
Written by
Kim TranBattery Storage Expert
Specialist in home battery systems and energy independence solutions. Kim analyses the rapidly evolving battery market to help homeowners decide if, when, and which battery to add to their solar setup.
Learn more about Kim Tran