Home Batteries Finally Taking Off?

Fronius Gen24 and BYD battery installation, Australia

Installation by DJM Electrical

This year’s Smart Energy Conference was abuzz with news on solar and batteries — more abuzz than a bucket of Queensland prawns on a hot tin roof.  The hottest of hot topics was home batteries — not because dodgy ones were spouting flame — but because their installation rate is soaring.  If growth continues, by the end of 2027, Australia could have as many home batteries as some optimists predicted for the year 2020.

An excellent source of battery information is Warick Johnston, Managing Director of Sunwiz.

Sunwiz is a solar consultancy company that does loads of market research, including on batteries.  They’ve given us interesting information in the past, and that is appreciated.  Warwick Johnston has been in the solar industry for 18 years.  Long enough for us to give him the nickname “Warwick-san” on account of how he’s not Japanese.  (It’s like how we call people with red hair “Blue”.)  He spoke at the Smart Energy Conference, and I’ll tell you the major points he made on home battery uptake.  While it wasn’t too far from what I expected, some points surprised me.

I didn’t attend the talk in person, but neither did he, so we’re even.  He appeared in video form. He wasn’t there in person due to family health reasons.  I guess he must be one of “those” sorts.  You know — people who love their family.  While there’s nothing wrong with that, I find that if you start loving your family, they expect you to love them all the time!

50% Growth In Residential Batteries

The big news is how battery installations are finally taking off, years after battery optimists thought they would.  Around 47,100 home batteries were installed last year.  That’s an increase of 50% from 2021. Commercial battery installations were also up.  The only area that saw a decline was utility-scale batteries.  Australia leads the world in building big batteries, so it may seem strange fewer megawatt-hours were added last year than the one before.  But because they’re so big, there’s a lot of lumpiness in how much capacity is added each year, so it’s not unexpected.

South Australia is the state with the highest portion of battery households.  There are several reasons, but the main one is the state’s generous battery subsidy that ended in July last year.  By my calculations, around 1 in 60 South Australian homes has a battery.  That’s 1.7%.

Home Battery Installations By Type

Warwick-san divided last year’s home battery installations into six categories.  From the largest percentage of installations to the smallest, they were…

  • 50% — A battery and solar system installed on a home without existing solar.
  • 25% — A battery installed at a home with existing solar.
  • 11% — A battery installed and the existing solar capacity was upgraded.
  • 9% — A new battery installed and the existing solar system was replaced.
  • 5% — Existing battery capacity at the site was expanded.
  • A “handful” were installed in homes without existing solar or solar being added.

I don’t want to reproduce any of Warwick’s graphs because Sunwiz puts a lot of work into them and uses them to help sell reports to earn a crust.  Or maybe even two crusts.  But if I make a crappy graph of my own, hopefully no one will be upset:

Graph of battery installation categories

My Thoughts

I’m a little surprised that 50% of batteries were installed along with a new solar system on a roof that was previously solar-free.  

I suspect many people buying a brand new battery and solar simultaneously looked at the return from both blended together and decided it was a good deal.  If they had looked at the excellent return from just getting solar and compared it to the much lower return from solar and a battery, I expect some would have decided to put off buying a battery for now. 

Expanding Existing Solar Can Be Difficult

Warwick-san said in 11% of battery installs existing solar capacity was upgraded.  There are two main ways to do this:

  1. Add more solar panels to an existing solar system.
  2. Install a second separate solar system on the roof.

While he sounded like he was referring to only the first category, I’m sure at least some people would have had a second solar system installed.  As they’re not mentioned elsewhere, I assume they’re included in this category.

One reason a homeowner buying a battery may want to install a second solar system is some battery systems are limited in the size of the solar system they can be connected to.  To have the desired total solar panel capacity on the roof, two separate systems can be necessary.

Update 22nd May 2023: Warwick Johnston of Sunwiz has confirmed the large majority of solar capacity expansions were done by adding an additional second solar system, rather than expanding an existing system — which is usually difficult to do.

Scrapping Your Old Solar

Around 9% of the time, a battery was installed, an old solar system was ripped off the roof and replaced with a new one.  It can make a lot of sense to replace a small old system with a larger new one that has higher efficiency panels and a fresh set of warranties.  It may make sense even if the solar system isn’t that old.

If you ask me how much solar you should install, my advice is to fill your roof!  Or at least install as much as will reasonably fit.  This is a good idea if you don’t have a battery, and if you do, it will help keep it charged on cloudy days and in the middle of winter.  It will also mean you’ll be ready for when you get an electric car — or a second or third one.  

Expanding Battery Capacity

In 5% of cases, what was called a “battery installation” actually involved increasing the capacity of an existing battery system.  If you want to expand your battery capacity, go for it.  But my advice is to try to avoid the need by selecting a suitable amount of storage capacity in the first place.  If you have money to spare and aren’t certain how much storage capacity you want, there’s no real point in getting a small battery and possibly regretting it later.  But if you can only afford a small battery, unless you’re confident it makes sense for you, I recommend thinking hard about if you can really afford a battery at all at this time.

Batteries Without Solar

A “handful” of batteries were installed in homes with no solar.  While this may seem strange, a solar-less home battery may be able to pay for itself under the right circumstances.  But I suspect the main reason people want them is for backup. 

While the user manuals of battery systems normally say they can’t be relied on to power life support equipment, if I were on life support, I’d want a home battery.  As well as a separate Uninterruptible Power Supply (UPS) in case one didn’t work.  I’d want a generator too, because who knows how long a blackout might last? 

Of course, if I’m on life support, I will have trouble testing the generator and following its maintenance schedule, so I might need some sort of robot.  Elon Musk says he’ll have one ready next year, so, translated into normal human English, that means about 20 years from now…  Goddammit!  It looks like I will have to love my family too!

Battery Trends

One battery trend mentioned by Warwick that we’re currently seeing all over the place is the shift towards the unification of batteries and inverters.  This is where the battery and inverter come from the same company.  This is useful because it means the hardware is (almost) certain to work well together. It eliminates finger-pointing where a battery manufacturer blames the inverter for a problem and vice versa.

Another thing he mentioned is a considerable number of battery manufacturers sell under 2,000 units a year, and many of them are likely to exit the Australian market. 

Warwick-san advised installers not to act as though they’ll only see their customers once.  He didn’t say this because batteries are still so unreliable they’ll be around a dozen or more times to fix them.  He instead meant there can be multiple opportunities to sell to one customer.  One household may want solar, then a battery, then expanded solar capacity, followed by expanded battery capacity, then an EV charger, etc.

Batteries Will Be Big

I don’t doubt home batteries will play a much larger role in the future than they do now.  This is because:

  • Lithium and other materials used to make them are falling in price.
  • While solar feed-in tariffs will rise in the National Electricity Market1 next financial year; after that, they’re likely to start heading down and this will improve the financial return from batteries.
  • Homes will consume more electrical energy as natural gas consumption is gradually eliminated and road transport goes electric.
  • Battery technology will continue to improve in reliability and affordability.

While batteries will be cheaper in future, I don’t know when they’ll fall in price.  So if you want a battery and buying one won’t cause financial hardship, go get one.  Even if it’s not a money maker, it can provide backup power and is good for the environment because it can store clean energy that otherwise may go to waste. 


  1. The NEM does not include WA, NT, or WTF.
About Ronald Brakels

Joining SolarQuotes in 2015, Ronald has a knack for reading those tediously long documents put out by solar manufacturers and translating their contents into something consumers might find interesting. Master of heavily researched deep-dive blog posts, his relentless consumer advocacy has ruffled more than a few manufacturer's feathers over the years. Read Ronald's full bio.


  1. Have read the statement “fill your roof” a few times on SolarQuotes. If you can fit 13.3kw of panels on the NNW side of your house would you consider some or the same capacity again on the SSE side to “fill the roof”. Where would you stop?

    • Depends a LOT on where you live.
      There’s a very big difference between Darwin, Brisbane, Sydney and say …. Hobart.

      Eg: Panels on the south side work VERY well in Summer in Brisbane. Our biggest power drain in Summer in Brissie is A/C, so they work well for us. They also pick up sunlight BEFORE North facing panels first thing in the morning in mid Summer, and later into the evening at the other end of the day.
      Winter- not so good, but our power use is then much less.

      • NSW South coast. The SSE side would definitely boost summer self consumption for the first half of the day. That was the reason I considered splitting system in a N and S side string. Certainly cheaper than a battery as keen as I am on getting one.

        • If you have a big house and an EV or two then 13.3 on NNW and 6.6 on SSE would be good
          That’s a 5kw string inverter on each phase.

          I have big house and EV with 10kw inverter and 13kw panels on NE.
          For more output in winter looking at installing more.

  2. Thanks Ronald for another informative and entertaining article. I always enjoy your writing and appreciate your advice.

    This time you saved the biggest surprise for the last sentence where I notice you’ve changed your tune. Not so long ago the tune was “Batteries are not good for environment because the renewable energy stored in them would otherwise be used by someone else on the grid in a more efficient way than a round-trip to a battery and back”.

    Has that situation changed somehow?

    Because I was surprised that the tune is now “Batteries are good for the environment because they can store energy that otherwise may go to waste.”

    I feel like the opposite of a homeowner who rushed out to buy a home in 2021 because the RBA said interest rates wouldn’t rise for ages. I rushed out and didn’t buy a battery because my RBA (Ronald Brackels’ Advice) said, “Don’t get a battery because they won’t pay for themselves and they’re not good for the environment”.

    So which is it? Are batteries good for the environment or not? Please advise.

    Still yours but slightly confused. Andy

    • Ronald Brakels says

      Hi Andy

      There has been a very large change in the amount of variable renewable energy on the grid since I wrote that the environmental benefit of batteries was overhyped. They have gone from 8.5% of NEM generation to 27%. This makes batteries much more useful for integrating renewables into the grid than they were and they will help reduce the curtailment of renewable generation. Also, while politicians are not perfect on this, those in government now generally understand that our coal power stations have to be shut down. This makes it less important to harm coal generation by forcing the demand for grid electricity down in the middle of the day. Reducing evening electricity prices – which batteries do – also helps. Another plus is the manufacture of batteries has become less environmentally harmful, although by how much is unclear.

      • Warwick-san says

        I agree with Ronald. We’re getting towards the point where there’s so much solar in our distribution network that having local energy storage (EV or stationary ESS) will play an important role in soaking up that energy so MORE PV can be deployed in that area AND the PV that is deployed won’t have its ‘volume’ turned down by the network operator. So batteries can now enable more renewable energy to be deployed.

        • One might think that a forward looking DNSP would know the suburbs where they are having oversupply issues – and rather than trying to turn down the export for users – would deploy a battery there for absorbing the duck curve and then exporting into the evening – if only the AEMO would create this category for them to do so and thus put off curtailment and network upgrades which we all end up paying for.

      • Thanks Ronald, I’m glad to hear that there is starting to be an environmental case for getting a home battery. How about the economic case? Has that improved at all? Power prices are up, FITs are down… I assume that improves the case for a battery. You’ve always said that they won’t pay for themselves for most households. Has that changed? Cheers, Andy

        • Ronald Brakels says

          The economic case for batteries is definitely getting better. They can potentially pay for high electricity consumption households under the right circumstances. Whether they make financial sense also depends on how much value people place on having backup power. Here’s an article I wrote on it. Things have improved since it was written, but not by a great deal:


          • Your calculations do not include the cost of funds. You should be using at least a 5% cost of funds on the battery purchase (think of it as the savings you’d get if you paid down the mortgage rather than buy a battery). Once you’ve done the right financial calculation pretty much all of the cities in your tables produce negative “savings”.

            Having done the calcs for my situation (16kW Solar) large house/kids/pool/computers, and having moved as much usage to periods covered by solar, we’d exhaust a powerwall overnight but the bulk of it would be shoulder/low TOU charges. The “savings” would take around 40 years to pay back the battery cost.

          • Ronald Brakels says

            There’s no calculations on that page for determining the financial return from a battery. It’s just made to help people compare different batteries.

            You can find information on determining the financial return from a battery in a basic way in various blog posts on the site. The article below is fairly old but, unfortunately, there hasn’t been a huge change in returns since then:


  3. We are on the SA PFiT and upgrading or grid connected storage would mean losing that

    Bought a ‘Power Station’ and 6kWh expansion batteries and second hand solar panels, just lying on the ground for now. Only utilising one 1200W 150V maximum MPPT we have been mostly off grid since November with the battery powering the fridge, washing machine, dishwasher, AV equipment and and LED lamp. When the batteries have spare capacity we use them for cooking and boiling water.

    Legal? Probably not. It will probably pay for itself before it dies given the spread between the FiT and kWh price.

    Agreed. If you can afford storage. Go for it. The grid needs storage yesterday

  4. Trevor Jones says

    The main point that you have not made is that adding a battery and providing backup power when there is no grid supply allows your solar to continue to operate. It is really frustrating to have solar on your roof while the sun is shining and not have power for your home.

    The other point is that many new homes are built each year and more and more are getting solar installed which would account for many of the new installs with solar and battery. What better time to get solar and if you are borrowing hundreds of thousands of dollars why wouldn’t you add a battery to the price.

  5. I installed solar and a battery at the same time because the family uses energy nearly exclusively in mornings and evenings, and not during the day. I liked that pathetic FITs weren’t the only benefit I’d be getting from the panels. Financially it will pay for itself within its warranty period, but like I’ve said here before about cars, cost recovery is a low bar that renewable deniers have imposed on the industry. Nobody ever bought a car because it was going to pay for itself. I paid for the extra functionality the battery brings to my home as well. Plus as a risk management thing, knowing that the grid will be potentially unstable for 5-10 years while they try to transition to full renewables.

  6. bosco seeto says

    As battery are so expensive, there are talk of community battery installation, what is your opinion about the topic ?

    • Ronald Brakels says

      While a considerable number of batteries will be built in communities to support the grid, letting households use a share of that storage as if it was their own home battery has major problems. In order to support the grid these batteries will need to be discharged and charged when the grid needs it and not when households necessarily want it. So either households can’t really use them as a home battery or lots of additional storage capacity will be needed to allow it and that’s not the most cost-effective way to reduce emissions.

      • I’m with Ronald on that too.

        Sharing data on a phone plan with your kids? (The kids would use it all, leaving nothing for you.)
        Sharing a car between multiple families? (The car would sit around every night when we’re ALL tucked up in bed. It would almost never be available when YOU actually want it.)
        Sharing a community battery- same deal, (unless it was absolutely massive).

        When you have your own battery, you understand the limits and use it accordingly, moving power demand when, and where you can. If it’s “elsewhere”, many people won’t give a damn, and will say “I’ll just use power when I want.”.

  7. This is part of my thinking about the longer-term plan for grid stability. Easier to do when you centralise everything, but it’s too late for that now, with so much rooftop solar out there. (And not saying that’s a better model, just an easier engineering challenge.) If we decentralise storage too, as is happening now at pace (I’m one of them), does that mean a major component of our grid is in the hands of individual householders, in perpetuity? How do we know they’ll do the upkeep, that they’ll have the funds to replace batteries as they come to end-of-life, etc.? Will we have to set up ongoing permanent subsidies to households to make sure this is being done?

    Lots of really difficult issues to solve.

  8. Batteries also give you time of use options, not just backup. To determine which electricity you’re going to store (grid and/or solar) for use later, to minimise cost. Maybe not enough to pay for themselves, though again I always come back to cars and other consumer goods, that never pay for themselves either. You could argue that a battery has only limited functionality compared to some of those other goods, so cost-recovery has greater importance. Though for most consumer goods, even cars, it’s arguable that many of the ‘needs’ we have for them were generated by the goods themselves.

  9. Tom Sjolund says

    Thanks Ronald, very interesting.
    We own a duplex we live in one unit and the other we rent out. We have 2 solar systems, for us a 6.6kW system with 4kWhr BYD battery module the other is just a 2.5kW system.
    We live in regional Qld and are pensioners, so we get a rebate which offsets the service fee for us but not for the rental. We have to separate smart meters installed.
    So my new plan is to increase the size of the rental system to 6.6kW and add a 16kWhr BYD battery and then take the rental off grid.
    We’ll also install another 3 x 4kWhr BYD modules to our system but stay on the grid and hopefully stay on the grid to take advantage of the proposed new FIT will go from 9.3c to 12.9c.
    This will be good for the environment and our pocket as well.

  10. George Kaplan says

    1 in 60 SA homes has a battery, or 1.7% of all SA homes, but homes without solar tend not to get batteries. What share of homes with solar does that translate to?

  11. Darrell Martens says

    I went hard-core “greenie-backie” on my decisions and only stationary batteries missed the cut. Even a battery-on-wheels pays off on total cost of ownership (when you want 4sec lux performance kit especially). And that was before Putin-on-the-fritz.

    I’m waiting for sodium/zinc/Al-graphene/Al-Sulphur/ZnBr-gel/pseudo-capacitors to kill stationary lithium by crossing the 12-15c/kWh LCOS. Might be waiting 5 years or might be 2 if CATL scale sodium … but it’s coming.

    (Suffice it to say I did a Saul Griffiths & it cut my $$ 50% pre-Putin and my CO2/CH4 70%)

  12. Paul McMahon says

    Since Dec 22 I have got a roof full of panels (20kW) with a battery (12.8kWh) and an all-electric house. Battery starts supplementing solar around 3.30pm and within an hour is powering the house. It’s cold at this time of year, so we use an average of about 4kW through the evening peak – so the battery is depleted before I go to bed. Morning peak (I want the RCAC heat on early when it’s -5!) is all from grid. More battery required – lucky Sungrow is modular!

    • Finn Peacock says

      Have you thought about charging the battery from cheap, overnight grid electricity to get through the morning peak?

      • Paul McMahon says

        I’m on a flat rate from grid as I buy at peak times, so no value in chasing off peak rates. Charging from the grid isn’t implemented – not sure how it could be done. Also interested in topping up house battery from EV (potentially using V2L capability). Paying for grid power when there’s 60kWh parked beside the depleted house battery seems ‘sub-optimal’! Use 1/5 of the EV into the house battery (V2L @ 2kW/hr from 11pm to 5am) and top up both batteries when the sun comes up.

      • Sorry if this posts twice. I’ve been doing the calculations on that as well. Right now we’re breaking even, even with late-evening and early morning use (for heating). The problem I’ve found is that retailers that offer good FITs usually don’t couple them with good off-peak rates as well. So you can have one or the other, but not both. They also vary the daily supply charge significantly, so that’s 3 variables to plug into the calculation. Plus if the FIT is a stepped rate by usage (like mine, 12c/kWh for the first 14 kWh per day, 5c after that), it makes the calculation even trickier. Is there a calculator for these scenarios?

        As the winter progresses I expect the FIT will become irrelevant (little export) and it’ll be an easier decision to just go with the best available time of use rates.

      • Wouldn’t that just mean that the Sungrow battery warranty would be exhausted in 5.5 years based on its 52MWh limit for a 12.8kW battery.

        • Ronald Brakels says

          Hi Harry. Charging at night will increase the battery’s energy throughput, but it won’t go through two full cycles a day in normal use. So the warranty should last considerably longer than 5.5 years. But if they did manage to get two full cycles out of it per day by discharging it when the household would otherwise have been using expensive grid electricity during peak periods it would result in an excellent return from the battery, so the short warranty period wouldn’t be much of an issue. But two full cycles a day is not practical in reality for households.

          • We’ve already worked out that the battery doesn’t provide an “excellent return”, costing 29c per kWh according to your prior article on batteries. Adding a low TOU cost per kWh charging cost to avoid the shoulder TOU is still likely to be far less than the reduction in warranted battery life.

            I’d like to see the calculations that make this “an excellent return”.

          • Ronald Brakels says

            Just assume I often speak in relative terms and my previous comment will make sense.

  13. How does one add a secondary solar system and can you mix different types? Say I have an existing North, West, East facing microinverter system maxing out my state export limit while keeping stuff under single phase, can I and/or would it make sense to add a 6.6kw South facing string solar system (instead of existing microinverters system) without having to upgrade to 3-phase and how would that connect to the existing? Would the costs involved in upgrading 1-phase to 3-phase just to get and additional 6kw (4.3 really because south facing) even be worth it? I’m thinking that my upgrade path would be getting a battery > 3-phase upgrade > more solar > more battery.

    • Ronald Brakels says

      How easy it is to add a second system will depend on the location. Some possibilities:

      1. The region has a 5 kilowatt export limit and a 10 kilowatt inverter limit and there is an existing 6.6 kilowatt system on the roof. Here it’s easy to add a second system.
      2. The area has a 5 kilowatt inverter limit. If there is an existing 6.6 kilowatt system then no additional inverter capacity can be added without expanding from single phase to 3 phase power. But one option to install more panel capacity would be to remove the old system and replace it with a hybrid inverter with a battery. With the right hybrid inverter this can allow considerably more than 6.6 kilowatts of solar panels without upgrading to 3 phase power.

      Provided you are allowed to add more inverter capacity, there’s no problem adding a 2nd string inverter solar system to a roof with an existing microinverter solar system.
      South facing solar can pay for itself but it will generally generate around 25% or more less than north facing panels. Whether or not it’s worthwhile comes down to location, household electricity consumption, and personal preferences.

      • Erik Christiansen says

        Having just mowed an acre with a tired old ICE ride-on mower, and finding the available EV mowers tinny and under-batteried, I’m keen to finish my tree change and build a mower with a pack of 4 or more Zenajis. (4*1.9 kWh = 7.6 kWh) With a small trailer behind it’d also do for fetching firewood.

        Given a pair of battery packs, one could charge while the other is in use. But you can’t reconnect the discharged one across the more highly charged one or there’s a helluva spark and high ongoing equalisation current. (The arc flash wouldn’t do your eyes or hearing any good, and there could be flash burns.) So there’d need to be separate charging for each. If that took the form of a pair of charger/inverters, the two battery packs could form a second house battery on (the majority of) days when not mowing. (The kangaroos do a really good job most of the time, leaving a lot of little black thank-you pebbles all over.)

        That battery is another variable in the energy shunting equation when there’s already a house battery, a HWS, an EV, and all sorts of domestic loads coming and going. I don’t believe even Victron DVCC computes for two batteries, so this is beginning to get interesting. Given the simplistic energy management model of available offerings, there’s much to be said for leaving it in “manual” mode, and sending in commands from a DIY controller, I think. (Would look into it now if I didn’t have to refurbish the garage floor, build a couple of wardrobes first, and move more furniture.)

        But at least some of the big isolated batteries in multiple vehicles need to be bidirectional when off-grid, certainly if generator run time is to be minimised.

  14. Roy Flynn says

    A little off topic, but I was wondering about the cost of home batteries.

    For the sake of the exercise, lets say a 60kwh home battery costs about $60k.
    I just bought my EV, about $50k. It has a 62kwh battery.

    So if I had a simple way to connect the car battery to my inverters, I could buy a whole car with included charger and have more capacity and a spare car!

    Even if I bought just a replacement battery, reputedly to be around $25k (for those VERY few car vendor who will give a price – they should all be forced to provide such costs!!), I would have a MUCH cheaper battery.

    What Have I missed??

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