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Recently I heard the news that sonnenBatterie were joining Australia’s emerging Solar storage market, so I contacted Sonnen’s new Australian managing director Chris Parratt to get the scoop. The reason for my interest is that the “sonnenBatterie eco” is an AC coupled battery. This means we can connect it to any solar system – old or new. Enphase has had a crack at an AC coupled solar battery but in my view, they failed. Since reviewing Enphase, I’ve been on the lookout for an AC coupled battery that works. Today, “hot off the press”, Chris sent the spec sheets. Let’s break it down.

To be clear, the sonnenBaterie ECO is not the model that True Value Solar are importing directly from Germany, and misleading consumers by saying that sonnenBaterie is: “Fully compatible with the Bosch inverter”. The sonnenBattery as an AC coupled battery so it can be coupled with any inverter. Why would you link it to the Bosch inverter that is no longer in production?

The sonnenBatterie is a completely different solution to the Tesla PowerWall, but for the sake of benchmarking, first this post will compare the two. Next, I’ll advise what I would do if I were buying a solar system today, with batteries in mind.

Pro’s of the Sonnenbatterie

  • sonnenBatterie is German Made.
  • As an AC coupled battery it can hook up to any solar inverter, or any AC generation source. The Tesla is currently limited to the Fronius Symo hybrid and the SolarEdge.
  • It is scalable from 2kWh to 16kW of usable storage, or up to 48kWh in cascading clusters. In reality, 10-16kWh should be more than enough for an average household. The PowerWall for comparison comes in 6.4kw packs. 
  • It is warranted for 10 000 cycles or 10 years. The warranty covers all parts. Theoretically, you could cycle it 2.7 times a day, and it would be still covered by the warranty. The Tesla also come with a 10-year warranty but only 3650 cycles, and only a 4-year workmanship warranty.
  • It’s expected lifetime is 20 years. Sure that’s not a warranty, but it means if you cycle it more than once a day, it should last 20 years.
  • It’s fairly compact on the larger end. From 4kW hours to 10kWh, it uses the same enclosure: 137cm tall, 64cm wide and 22cm deep. That’s about the same size as the 6.4kWh Tesla. If you want larger than 10kWh, the enclosure is just 50cm taller.
  •  The Maximum efficiency is 93 percent. More data would be needed to compare it to Tesla’s DC coupled 92.5 percent round trip efficiency. However being AC coupled, the total system efficiency would be less than a DC coupled system.
  • It will be able to run as an “emergency power supply” in 2017 with an upgrade.

Con’s of the sonnenBatterie

  • It’s a bit lacking on its charge and discharge rate. On single phase it’s 2400W, and for three phase it’s 3300W. The Tesla Powerwall charges and discharges at 3300W. An oversized solar system will sometimes want to charge faster than 2400W, and average household would have an evening maximum demand of higher than 2400w. However, 2400w would absorb a big chunk of surplus power, especially if your solar system was designed with appropriate load shifting.
  • It’s heavy. At 116kg, the 6kwh option is even heavier than the 97kg Tesla Powerwall, but that probably speaks of its quality. Unlike the Tesla, they don’t expect you to hang it on the wall!
  • It’s IP 21 and can only operate up to 35degrees. In Queensland weather, this would limit the areas you could install it.
  • This is the big negative. The sonnenBatterie costs well over $2000 per kWh of storage capacity plus install. With far superior technologies like Redflow costing less, it’s hard to see sonnenBatterie ever becoming a cost-competitive solution.

My Advice

If you planning to install a battery ready solar system, I would advise you away from an AC couples solution purely based on Price. Since DC coupled batteries are significantly more affordable, it would be far more prudent to install a quality hybrid inverter now (such as a Fronius or Redback), and add a quality DC coupled battery when prices come down further. Whatever you do, don’t be sold on the false hope that a second rate inverter like Bosch is compatible with the sonnenBatterie. Every inverter is compatible with the sonnenBatterie, but using the Bosch inverter would be like putting a Rolls Royce engine into a Datsun.

Before you purchase solar from anyone, please do your background checks on the company. Especially if you are reading this because you have a quote from True Value Solar.
Here is a simple 5 step background check.

Conclusion

As a battery, the sonnenBatterie seems to be serious competition for the PowerWall. As an AC couple battery, you don’t need to purchase an expensive inverter now. It is compact and easy to install on the ground, and one unit can take up to 16kWh of storage. Its warranty is better than the PowerWall. One downside is the single phase version will only charge and discharge at 2400w, but the three-phase version meets the PowerWall’s 3300w. As with most batteries, you’ll need to choose carefully where to install it. However all said and done, batteries need to be cost effective, and AC couples solutions such as the sonnenBatterie seem to be missing the mark by a long way. Choosing a hybrid inverter today, for a DC coupled future, would be the way I would advise you to go.

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11 Comments on "Sonnenbatterie review"

11 Comments on Sonnenbatterie review

Mark C said : administrator Report 3 months ago

Hi Doug. No, I haven't really kept up with Sonnen - but I have heard good things. Redflow (ZCell) has had major teething issues. Please don't do car batteries!!! The industry doesn't need the bad publicity of batteries causing house fires :)

Doug McEwan said : Guest Report 4 months ago

Any update on these SonnenBatterie since your article April last year? Has the price dropped to be competitive yet? I also liked the idea of the Z-Cell bromine batteries however they are also way too expensive. I might just stick to putting in a few car batteries into the system lol

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Mark C said : administrator Report 7 months ago

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Mark C said : administrator Report 7 months ago

Hi Dave, it depends on where your mother lives. In Queensland, batteries don't have a great payback period yet. But in other states where they use "Time of use" a battery may make more financial sense. I'm more in favour of Tesla as a battery even though it is AC coupled, but it depends on the situation. I'm keeping my eye on Solarwatt, which will have it next model battery released soon.

Dave said : Guest Report 7 months ago

Hi There, Thanks for writing the review. Valuble info. My mother has a solar system installed and never got the feed in tarrif because the company ripped her off and she didn't get certificate. Anyway she wants to use a battery setup so shes not sending power to the grid and not being paid. Do you think the batteries like Sonnen or as you say here DC batteries are best? or to wait for fuel cell systems to be available?

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Plu42jiKoyh said : administrator Report one year ago

I was Luke. I've fixed up a typo, and the redflow wouldn't be half the price. I probably should also change that because I'm not a fan of Redflow at the moment. See the updates on my review Hopefully, they will change their warranty soon. I'm more inclined towards the Tesla Powerwall and Redback with Pylontech.

Luke said : Guest Report one year ago

were you referring to REDflow in the cons section of this article? couldn't find anything on reflow but Redflow popped up.

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Plu42jiKoyh said : administrator Report 2 years ago

Hi Doug, That's a hard one to advise via a comment. It will depend a lot on what feed in tariff you have. Are you based in the Energex area (South East Qld?). If so we can help you with options, and give you advice on the viability of using batteries. Ph 32683836

Plu42jiKoyh said : administrator Report 2 years ago

Hi James! So Sonnen is where you ended up - good to know and lucky for Sonnen! It was a while since I posted this review, and I'll have to revisit it. I couldn't get a lot of info at the time of writing. Interested to hear more, and I'm guessing pricing has changed somewhat since I looked at it.

Doug Slatter said : Guest Report 2 years ago

I have 2 seperate PV systems, a 1.1kw gross metering system & a 2.85 kW. . Nett metering system on 2 seperate SMA inverters. How can I marry them into one system with battery backup still selling excess to the grid? Battery type &costs? Thanks Doug

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james said : Guest Report 2 years ago

Hi Mark, Nice blog, its important however to also look at all of the other product advantages and to not just focus on the batteries and cost per kWh. Whats unique about the sonnen unit is that it already has the ability to do what other companies are developing, i.e. the ability to control loads. The sonnen unit also already has it built in intelligent algorithm to learn and predict the lifestyle of the homeowner to chose when to charge and/or discharge the batteries and manage loads. The unit already takes in BOM data to also choose how to manage loads and charge/discharge the batteries based current and forecast climate. sonnen uses Z-wave for direct appliance control its a very clever meshed based system, with socket adapters the unit measures loads of appliances and it will manage them in either auto-intelligent mode or you can control them via the smart phone app. The warranty is good too, its 10 years or 10,000 battery cycles, whichever comes first. Although the unit is new to Australia its by no means a start up, sonnen have well over 12,000 systems already up and running in Europe and the us. There's a 3-phase version to be released before the end of the year as well a commercial offering with up to 240kWh's worth of storage.! Hope that's helpful for you... All the best;

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james
Guest
Hi Mark, Nice blog, its important however to also look at all of the other product advantages and to not just focus on the batteries and cost per kWh. Whats unique about the sonnen unit is that it already has the ability to do what other companies are developing, i.e. the ability to control loads. The sonnen unit also already has it built in intelligent algorithm to learn and predict the lifestyle of the homeowner to chose when to charge and/or discharge the batteries and manage loads. The unit already takes in BOM data to also choose how to manage… Read more »
Doug Slatter
Guest

I have 2 seperate PV systems, a 1.1kw gross metering system & a 2.85 kW. . Nett metering system on 2 seperate SMA inverters. How can I marry them into one system with battery backup still selling excess to the grid? Battery type &costs? Thanks Doug

Luke
Guest

were you referring to REDflow in the cons section of this article? couldn’t find anything on reflow but Redflow popped up.

Dave
Guest

Hi There, Thanks for writing the review. Valuble info. My mother has a solar system installed and never got the feed in tarrif because the company ripped her off and she didn’t get certificate. Anyway she wants to use a battery setup so shes not sending power to the grid and not being paid. Do you think the batteries like Sonnen or as you say here DC batteries are best? or to wait for fuel cell systems to be available?

Doug McEwan
Guest

Any update on these SonnenBatterie since your article April last year? Has the price dropped to be competitive yet? I also liked the idea of the Z-Cell bromine batteries however they are also way too expensive. I might just stick to putting in a few car batteries into the system lol

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