Punters Surprised: Prices Publicised Show Batteries Subsidised Cost More Than Surmised

sonnen battery prices

Prices Sonnen Has Published Show Their SA Subsidised Batteries Of Any Size Ain’t Cheap!

In what could have been good news, Sonnen’s Australian website now gives prices for home battery systems bought directly from them after the South Australian battery subsidy is applied.  Unfortunately, they are not cheap and range from $9,375 for a 6 kilowatt-hour battery to $15,175 for 14 kilowatt-hours.

This graphic from their site shows prices for systems ranging from 6 to 14 kilowatt-hours:

Sonnen battery system prices

At these prices it’s essentially impossible for the battery systems to pay for themselves.  The good news is you can shop around and get a better deal from one of Sonnen’s partners.  It appears you have to pay a premium to buy direct from Sonnen.

The Type Of Sonnen Battery Is Unclear

The batteries are called “sonnenInklusiv”.  Using my translation program I see the word “inklusiv” in German means “LANGUAGE NOT RECOGNIZED”, which is an interesting choice to call a battery. But I like it.  To me it says, “Our batteries don’t care what language you speak.  They just work.”  Also, “inklusiv” sort of sounds like the English word “inclusive” so it’s easy to remember.

The sonnenInklusiv batteries increase in capacity in two kilowatt-hour steps.  This means they use 2 kilowatt-hour battery modules like Sonnen’s 8th generation and earlier systems.  But Sonnen’s 9th generation batteries use 2.5 kilowatt-hour battery modules.  This means I’m not certain what generation they are and I don’t know if they are going to stick with 2 kilowatt-hour modules or change to 2.5.

Just to make things a little more confusing, Sonnen’s Australian site used to say their systems increased in 2 kilowatt-hour steps, but at some point in the recent past they changed it to 2.5 kilowatt-hours.

Sonnen battery capacity

From Sonnen’s Australian website.

Currently it appears that both types can be obtained from Sonnen’s partners.

Includes Installation?

The Sonnen battery prices should definitely include installation.  Surely they would have to?  Given the prices they are charging after subsidy I find it inconceivable there could be an additional charge for installation.

However, on the Sonnen site it doesn’t actually say it includes installation.  I’m sure it does, but if you are getting one, check just in case.

Will They Pay For Themselves?  Inconceivable!

At the prices Sonnen is charging, these batteries won’t pay for themselves under realistic conditions.  It’s not even possible for the smaller batteries under wildly optimistic conditions.  To show you what I mean, let’s look at the sonnenInklusiv 10 kilowatt-hour battery.

Sonnnen battery payback

Let’s say you use 10 kilowatt-hours of stored electricity from it everyday.  That’s more than is reasonable to expect for any normal household, but let’s just run with it.  In South Australia solar feed-in tariffs of 16 cents or more are common and grid electricity costs around 38 cents a kilowatt-hour.1  If the battery system has a round trip efficiency of 90% then each kilowatt-hour of storage used at night will only reduce your electricity bill by about 20 cents.  This is because when you store solar energy in the battery for later use you forgo the feed-in tariff you would have received and you have to put more than one kilowatt-hour in to get one-kilowatt-hour out.  This means the battery would save around $2 a day.

Over a year the savings would come to $730.  At this rate it would take over 16 years to save the $11,775 purchase price of a battery with a 10 year warranty.  If you take a more realistic approach and take into account normal expected usage, capacity deterioration, and cost of capital, things get much worse.  The two larger batteries cost about 8% less per kilowatt-hour but that’s not enough to make them pay for themselves and the cost per kilowatt-hour is considerably greater for the smaller batteries.  If 6 kilowatt-hours of stored energy is used everyday from a 6 kilowatt-hour battery, it would take over 20 years for the savings to equal the purchase price.

Sonnen Offers Finance At 4.2% Or Less

Low interest loans are available as part of the battery subsidy and also apply to rooftop solar purchased along with a battery.  While Sonnen’s prices are high, the interest rate charged if you decide to borrow to buy the battery aren’t.  This image shows the monthly charges you will pay over 84 installments (7 years) if you finance the purchase:

sonnen battery finance

The interest rate comes to 4.2% for the smallest battery and gets down to 3.8% for the largest one.  That’s better than I expected.  If you decide to finance your battery, check the interest rates as they may vary.

The Sonnen Site Needs Work

If you go to the Sonnen site and tell it you want to “claim your battery subsidy” the first steps are easy.

You answer some straight forward questions and they recommend an expensive battery.  But after that it gets weird.

  1.  They ask for your NMI number without telling you what it is or that it’s on your electricity bill.  (It’s your National Meter Identifier number.)
  2. They ask for your meter ID without saying what it is or showing pictures of electricity meters with its location pointed out.
  3. They ask for identification details at a point when no one should have decided to buy the battery as no technical details have been given apart from its capacity and this doesn’t match up with information elsewhere on their site.
  4. They ask “Are you operating a life support machine?”2 which is reasonable, but then they ask, “Do you have multiple sclerosis?” with no explanation of why they are asking about that particular condition and not others.

I suspect very few people have decided to go ahead and purchase from Sonnen after seeing their prices, otherwise enough people would have complained for them to fix this.  But this is just a suspicion of mine.  I could be wrong.  Maybe they’ve sold — I don’t know, say 20,000 units?

I was planning to enter all the numbers and identifying information they wanted so I could move on to the next page and see what was there, but for some reason I became nervous and couldn’t bring myself to do it.  I don’t know why.  It’s not as if a German company would misuse the information3.

You Can Shop Around For A Cheaper Sonnen Battery

Fortunately, it’s possible to get Sonnen batteries at a lower cost from Sonnen’s partners than directly from Sonnen themselves.  This isn’t really surprising when you think about it because there wouldn’t be much point in becoming a Sonnen partner if Sonnen was going to install batteries at a lower price than you could.  One potential customer told me he was quoted almost $1,000 less by one of Sonnen’s partner’s.  I’ve also been told by Mark Moody of Solaworx that he has organised a 12.5 kilowatt-hour Sonnen system for $11,500.  Going by cost per kilowatt-hour that’s over $2,000 cheaper than a similar sized battery direct from Sonnen.  Clearly it pays to shop around.

More Choice Starting Next Year

At the moment only Sonnen batteries receive the South Australian subsidy because they’re building an assembly plant in Adelaide.  Other battery manufacturers will be able to receive it at the start of next year.  Or possibly the 30th of December depending on how literal the state government was being when they said 9 weeks after the start of the scheme.  At that point, whenever it is, there should be much more choice and competition.

I don’t know what battery systems will be able to receive the subsidy, but one that’s likely is the Tesla Powerwall 2.  Tesla recently increased both its price and their estimate of how much it will cost to install.  According to them it was a coincidence this happened just before the South Australian subsidy started.  If we use the middle of their installation estimate then after the subsidy is applied an installed Powerwall 2 will cost $9,275.  That’s 39% less than the $15,175 Sonnen is asking for their similar sized 14 kilowatt-hour battery. And the Powerwall 2 comes with backup.

Hopefully there will soon be a wide range of batteries available under the subsidy.  I suspect Sonnen’s will be among the higher quality ones.4  But unless they lower their prices they are not going to be among the cost effective ones.


  1. If your solar feed-in tariff is less and/or your grid electricity charge is higher after discounts have been applied, I strongly recommend finding a better electricity plan.
  2. Not just at the moment.
  3. My grandfather used to be a foreman in a German company.  He would cycle over to Germany everyday to work.  The border guards would search him for contraband but never found anything.  This was because he was smuggling bicycles.
  4. I inherited some clothes from Germans who just happened to die after I found out they were the same size as me and the quality of the clothing was incredible.  I never actually got to wear them as my father stole them as he is the same size as me.  He said they were reparations for that time I annexed the bathroom.  How was I supposed to know it was against Council regulations to turn a bathroom into an annex?
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. The challenge I see is that installing solar reduced my annual power bill to somewhere in the region of $500. If I could get a 50% saving on that, that would be a saving of $250/year. On that basis, it would be almost impossible for a battery system to pay for itself. Some more fundamental changes need to happen for battery systems to be worthwhile.

    • The blood of our Australian heritage is still running strong amongst these solar installers and specially these battery storage companies. Am a pensioner and I might have to live beyond a hundred for me to recoup expense in getting a solar system and storage, even with all that fancy rebates, which doesn’t actually help the home owner but feeds the commercial greed.

      • Ronald Brakels says

        A battery system, even a subsidized one will be a bad idea for many pensioners as they often won’t use enough electricity overnight to make it worthwhile at current prices. But just to be clear I’ll mention that solar by itself can definitely pay, especially if people are at home during the day and using the electricity produced. This article goes into the simple payback time for solar systems in each capital:


  2. This means the battery would save around $2 a day
    Which at 16cents feed in is 12.5 kwh from lets say a 3kw solar panel upgrade

  3. Sonnen Quotation from one of their aproved installers:
    1 x Sonnen Eco 8.2/16 Battery
    1 x Sonnen sonnenProtect 2500

    PLEASE NOTE: No allowances have been made in your quote for the following:
    outside installation enclosure, extra cooling and ventilation equipment or
    installation, extra materials and isntallation for difficult site access, upgrading of
    internet infrastructure.
    Energy Storage 16.00 kWh
    Utility Meter Not Included
    Includes Standard Installation
    Warranties 10 Year Whole of System
    5 Year Installation
    System Cost(ex GST) $22,254.55
    Plus GST $2,225.45
    Less Rebate ($6,000.00) (Indicative)
    You Pay(Inc GST) $18,480.00

  4. It does not matter what facts might be presented, the general uninformed public will just go ahead and have one installed anyway and for what possible reason? To keep up with the Jones family?

    And if you pay cash then look at the losses involved by no longer having that money in a high interest savings account.

    • First, find any “high interest ” savings account in Australia !!!
      Secondly, Sonnens’ ‘high price’ simply reflects commercial reality wherein Sonnen is supporting its distribution chain by not undercutting it !

      • UBank, ING Direct, CUA. I have used all three, I switch them around as rates and conditions change. They are all around 3% for low risk investment with the Government’s savings protection up to $250,000.

        3% on $18,000 is $554 PA in interest.

      • A simple 10% returm is available, and doesn’t depend upon ‘investment experts/fees.
        Open a (free) account with, say, Comsec and BUY bankshares. The major banks make a point of paying a dividend of about 6% pa (on one occasion I remember even borrowing the money overseas to be able to do so). The exact figure will be determined by exacctly how much you pay for them initially.
        (in the last few weeks the CBA price has risen from about $65 ~$70)

        In any case, tht return is fully franked which ~ depending upon your own tax bracket ~ can be calculated at about half as much again as the div. All up, a ‘rate’ of nearly 10% pa…… and safe as anything can be, since the government cannot/will-not allow the banks to fail.
        But wait!! there’s more!!.. If you can time it right, and with a little luck, you can get tht sme sort of return from EACH of the major banks pa.

        Why would anyone with more than three braincells piddle about comparing watts and the weather for a gain of from zero to about 3%??

        • Your appear to be Trolling based on what I have seen of your posts so far.

          Those high returns is pure speculating and there are no guarantees and could return a loss.

          And you are missing the point. The $554 (I did not include the compounding portion) could have been used to help pay for any usage during non solar hours.

  5. Greg J Greet says

    It ain’t necessarily so. I’m off grid in one location. The ‘capital contribution’ to connect is $50-100K! Ignoring generators, there is possibility that the batteries would pay for themselves in a PV system in less time than indicated in the article, particularly given the need for energy security in times of no/ low solar output.

    • Mike Gaskin says

      Also, if you live in the third world with very high rates of grid failure, having backup options is worth more than just the price of batteries and a payback period. How much light and refrigeration and just being able to live normally worth when the power fails often?

      • @Greg: Your situation is far different to most, for you it probably adds up.

        @Mike: While I can concur with what you are saying fact is we dealing with batteries for people living in Australia not other places in the world.

        • What do you mean “other places in the world”? I’m talking NEW SOUTH WALES & only 100kms from Canberra. There are PLENTY OF OTHERS WITH SIMILAR SITUATIONS!

        • I completely understand the economics of the argument and agree. But as I mentioned consider what it is like to not have power for two weeks at a time. I tell you that will change how you look at what power is worth to you.

  6. Bret Busby in Western Australia says

    Whilst the above apparently applies to only South Australia, as one of the rare states in Australia, that appears to have made it into the twenty-first century (no doubt due to receiving a higher per capita proportion of the GST revenue, that the state of poverty, WA), an aspect that I find interesting, in the above report, is that the “low interest loans” are for only up to seven years, whilst the purported warranties are for ten years.

    I expect that, if the duration of the warranties for the batteries, was genuine, the “low interest loans” would be for up to the duration of the warranties.

    That is, unless Sonnen intends to to a “True Value Solar” (also, a german company) job, and withdraw from Australia, before the warranties expire, so that, like the domestic rooftop photovoltaic systems on this property (not from “True Value Solar”), the warranties are not worth the paper upon which they are written, due to no presence in Australia.

    A significant problem with the rooftop photovoltaic industry in Australia, is the disappearing act, leaving cusomers with inoperative systems and void warranties, due to the disappearing act.

  7. What about a battery in my situation, I have 10.6 kw panels and an 8.2kw fronius with 5kw export limiting.

    Meaning alot of the time my system is throttled how do I figure out if a battery will pay for itself in my situation?

    • Finn Peacock says

      Great question – needs a blog post to answer. But yes – a battery will have slightly better payback for you because it can save your ‘wasted’ solar kWhs.

      I’ll add it to the To Do list.

      • A battery could save you “wasted” solar kWhs and so have a better payback than otherwise, but probably still not good enough to be worth while unless you value other aspects of a battery such as the back-up power it can provide as well.

        I’m going to assume you live in South Australia for no good reason (except that I live in SA and have an 8.2kw Fronius inverter so I know something about that setup) and that you have single-phase power so SA Power Networks will only allow you to have a 5kw inverter, or in your case a larger inverter with an export-limit. This also means you have a Fronius smart meter installed because that’s required in order to do the export limiting that you have. This is a smart choice because it means you can install more than the 6.66kw of panels that you would have been limited to with the STC rebate if you had stuck with a 5kw inverter and means that even though it is limited to exporting 5kw, if you self-consume 3.2kw then it can still get up to its maximum output of 8.2kw. With the current high feed-in tariffs you’ll probably get a good return on the larger system (not as good as the first 5kw, but at least worthwhile).

        A battery will have some challenges though. It appears https://www.solarquotes.com.au/blog/sa-power-networks-inverter-limits/ that SAPN impose a total limit of 10kW. This means that you have to DC-couple your battery which is tricky since the Fronius you have doesn’t support that, or AC-couple with a maximum total of 10kW which means the battery can have a maximum inverter capacity of 1.8kW, which severely limits your choice. It seems crazy to me that they put limits on the battery inverter when it never exports to the grid, but that seems to be the case. Maybe you can retrofit a GoodWe BP https://www.solarquotes.com.au/blog/goodwe-bp/ on the solar panel side to get around this, but it will only be able to charge from some of your panels and you can’t set it up to provide power in a blackout. The other option is to throw away your inverter and buy a hybrid inverter, but nobody like doing that, especially with a nicely made one like a Fronius.

        Your second problem is that to fully-utilise your nice new battery you need to avoid charging it in the early morning because then on a sunny day you will probably fully charge it before you get up to 5kW of production and your export limit kicks in, so you could end up not getting any of those free kWhs to charge it at all. A simple timer so it won’t start charging until 11am or so would help, but to get all the kWhs you can you’d need something much smarter than that. If you thought it was hard to buy a battery before with the 10kWh total inverter limit, it is virtually impossible to buy something useful now. In fact, I’m not sure that there is any battery available that is smart enough to soak up all those excess kWhs exactly the way you’d like it to.

        So, something else you might want to think about instead of a battery is a hot water relay: https://www.solarquotes.com.au/blog/using-fronius-inverter-smart-meter-relay-make-solar-electric-hot-water/. Since you already have a Fronius inverter and a Fronius smart meter, you may be able to have one of these installed for a little over $200 (although in reality it is unlikely to be that low for a standalone job). And since you have an electric off-peak hot water system (I know you probably don’t, but just go with it for the sake of the story), you can hook that up with the relay and start using your wasted solar to heat your tank. It isn’t going to perfectly use your excess kWhs either, but I think you might actually be able to program it to get reasonably close.

        And if you want even better control then you can get the Fronius Ohmpilot (although as you can read in the article it wasn’t available in Australia when it was written and as far as I know still isn’t). The Ohmpilot goes one better and doesn’t just let you switch on and off the hot water element, it can control exactly how much power gets used by the element, but due to its questionable availability you might want a different Solar diverter instead https://www.solarquotes.com.au/blog/divert-excess-solar-pv-hot-water-cylinder/.

  8. over and over and over again!—> Deep cycle AMG etc. lead/acid batteries will store one kw for UNDER $85. Buy more and you can get them for about $1.60 per ah ~ with a warranty of 3 years (which means that properly handled they can last up to 8 years in my experience; but EXPECT 5 years.
    Why would anyone with more than three braincells even consider being hooked to a system (including the grid) which gives them no autonomy, no control of fluctuations (including power supply and prices) and which can cost a fortune to ‘have installed’ ~ a job any half-witted chimpanzee could do?
    Fair dinkum!!!

  9. One thing I do find encouraging is that we are at last beginning to see the emergence of a ‘battery market’ with various suppliers offering acceptable products..

    So far as the ‘average’ residential grid-tied consumer with roof-top PV is concerned though, might still be a while yet before it becomes ‘economic’ to consider adding a battery to their home system.

  10. Mike Gaskin says

    I have been looking for modern Lithium batteries here in Mexico for two years and to date cannot find a vendor. Very expensive to import from the States. Can order from China but dont trust the pay first and hope you get them deal.

  11. What if the FIT goes down to 4 cents ? or zero

    • Ronald Brakels says

      As the average wholesale price of electricity falls, which is the cost of generating it, the feed-in tariff will also fall, but so will the cost of electricity, so the economic benefit from batteries should remain roughly steady. Other components of electricity bills have the capacity to fall but that’s not likely to happen in a hurry. If they do fall that reduces the economic benefit of batteries. The general trend at the moment is for grid electricity prices to trend down in real terms, which reduces the benefit from batteries. But I expect the cost of batteries to come down at a much faster rate.

  12. Before you all started speaking in acronyms and a language I don’t understand – I could keep up with kWh, after that I became dazed and confused, and my eyes glazed over — I really appreciated the tone and humour in the article.

    “3.My grandfather used to be a foreman in a German company. He would cycle over to Germany everyday to work. The border guards would search him for contraband but never found anything. This was because he was smuggling bicycles” Giggle-snort!

    Thanks for attempting to demystify, Ronald—and if I understand the intent of your last comment correctly, it was ‘hold your horses’, right?

  13. What about we grey nomads living in our Rv we would like to buy lithium batteries 24volt or 12volt what do have for us?

    • Ronald Brakels says

      While you can get lithium batteries marketed for caravan or RV use a quick look online shows they tend to be very expensive. If you are living in your RV and so using them daily it’s you may be able to get your money’s worth out of them, but I’d look very carefully at the warranty and how many cycles it covers. If you are using lead-acid batteries I wouldn’t be in a rush to change to lithium unless you are confident the product suits your needs or you willing to a risk to try out something new. Note that for every 10 kilograms in battery weight you save you only reduce fuel consumption by about 1 litre per 10,000 kilometers.

  14. Ronald Brakels says

    Moderator note: I am specifically not publishing a comment here that called another commenter dopey. This is Australia, so I’ll kindly ask you to not respect each other, but you do have to be polite. Or at least polite by our national standards, which is bloody polite in my opinion.

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