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Detailed reviews and information of the best solar panels, inverters and batteries. Plus hybrid and off-grid solar system reviews and information articles on how solar and battery systems work.

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Reviews and information of the best Solar panels and inverters from SMA, Fronius, SunPower, SolaX, Q Cells, Trina, Jinko, Selectronic, Tesla Powerwall, ABB. Plus hybrid inverters, battery sizing, Lithium-ion and lead-acid batteries, off-grid and on-grid power systems.

Sonnen Battery Review

Jason Svarc

sonnenBatterie ECO - Copy.jpg

Company background

Sonnen founded in 2010 is the leading Germany lithium battery system manufacturer and the largest residential battery company in Europe. Until recently Sonnen also known as sonnenBatterie had deployed the largest amount of home battery systems globally surpassing even Tesla and LG chem, however the competition really heated up over the last few years with many low cost battery systems entering the market.

Sonnen being a premium option also has a premium price and this can be a barrier to those on a tight budget. To help reduce pricing and become competitive in other markets Sonnen has began manufacturing and assembling systems in California in 2015 and more recently in South Australia (Nov 2018) with the aid of local Government rebates and incentives.

South Australia Home battery Scheme

Since the announcement of the South Australian Government home battery scheme worth $100 million and the opening of the Sonnen battery assembly plant in Adelaide, the Sonnen battery has become headline news in Australia. Home battery systems installations in Australia are predicted to soar over the coming years due to a combination of Government incentives and high power prices. The scheme will provide a subsidy of $600 per kWh of storage, up to a maximum of $6000 with 40,000 grants currently available. Read more about the battery Scheme here.

Inside the battery

Sonnen systems are made up of individual 2.5kWh (KiloWatt hour) lithium battery modules which are linked together in various capacities from 5 to 15 kWh. Like many other Lithium battery systems the usable capacity is rated at 90% of total capacity, so a 10kWh Sonnen battery will provide 9kWh of ‘usable’ energy.

The modules use LFP or LIthium Ferro phosphate cells manufactured by Sony and are some of the most reliable and longest lasting cells available backed up by an impressive 10 year, 10,000 cycle warranty. The Sony cells come at premium price which puts the cost of the sonnen systems above most other batteries on the market. To become more competitive sonnen have be rumoured to source cells from leading Chinese manufacturer PylonTech technologies. PylonTech is well known in the energy storage industry and has proven to make reliable cells but have a higher rate of degradation over time compared to the Sony lithium cells. With the impressive 10 year or 10,000 cycle life warranty (details below) the premium Sony cells will no doubt be used in all systems sold in Australia.

Sonnen battery Options

Sonnen offer two different battery systems suited to different applications. The Sonnen ECO which can be retrofitted to homes with an existing solar installation and the Sonnenbatterie hybrid or all-in-one system which is not yet available in Australia.

  1. Sonnen ECO - Modular AC Battery

    The SonnenBatterie ‘ECO’ system is much like the Tesla Powerwall 2 in that it is an AC battery with built in power inverter, however unlike the Powerwall 2 which is only available in one size the Sonnen is modular system made up of 2.5 kWh battery modules. Storage capacity starts from 5 kWh (2 x modules) up to 15 kWh maximum. The power output is rather limited at 3.3kW charge and discharge which means a larger 15 kWh capacity battery could take 4 hours or more to charge which may become problematic in the temperate cooler states with short winter days or if shading is a issue. The Sonnen ECO is a great retrofit option for homes with an existing solar installation.

    Solar Inverter Required - Like most battery systems the Sonnen battery requires an additional solar inverter to function with a solar array. Since this is an AC coupled battery the Sonnen is compatible with all solar inverters as long as the inverter is sized large enough to charge the battery in an appropriate amount of time. Depending on your location and energy consumption you will generally require a minimum 4kW solar array to supply household appliances and charge the battery. An accredited solar installer or designer should always be used when selecting and sizing a solar array or solar energy storage system.

    See the full SonnenBatterie ECO specification data sheet here.

  2. Sonnen Hybrid - All-in-one System

    The SonnenBatterie Hybrid is the all-in-one hybrid system with a solar inverter, charger and battery in the one simple unit. The hybrid option has a maximum solar PV capacity of 6.4kW and nominal inverter rating of 5.5kW (3 phase). However the battery inverter is still limited to 3.3kW for battery charging and discharging.

Sonnen battery ECO and Hybrid specifications.jpg

See the full SonnenBatterie Hybrid specification data sheet here.

For larger residential or commercial (3 phase) buildings requiring more energy storage, like other battery systems the SonnenBatterie can also be setup in a ‘cluster’ with a maximum of 45kWh total capacity (3 x 15 kWh).

Sonnen battery cabinet size options.jpg

Limited Backup Power

Sonnen battery Backup box.jpg

The Sonnen ECO and Hybrid systems cannot function as a backup power supply or UPS without additional components. To enable backup power in the event of a blackout an external Backup box will need to be installed at additional cost. The backup box, which looks like a tiny version of the battery system, isolates the house from the grid if it detects any issues with the electricity supply and can supply limited power for emergency backup.

Unfortunately the backup box only offers a very limited 1.8kW of continuous power out with a maximum surge rating of 4.1kW for 2 seconds. This is adequate for backing up basic loads such as lights, computers, and a fridge, but will not be able to backup anything substantial such as kitchen appliances or air-conditioning systems.

For those who want to go off-grid sorry it is not designed to function as an dedicated off-grid power system. There are many dedicated off-grid and powerful hybrid backup options available - see here for more details about dedicated off-grid systems. Consult a professional off-grid designer / installer for more information.

Larger backup option now available

Sonnen will soon be offering a slightly larger backup option called the SonnenProtect which provides up to 2.5kW continuous output. It may also function as a UPS but unfortunately not if a blackout occurs during charging. Still this is an improvement over the Backup-box but it should be noted that it cannot charge from solar during a blackout.


Sonnen battery Vs Tesla Powerwall 2

There are two main differences between the Sonnen and Tesla AC batteries, the first being that Sonnen ECO is available in a range of different sizes with capacities from 5kWh up to 15kWh and the second is Sonnen use Lithium Ferro Phosphate or LFP battery chemistry as opposed to Lithium NMC of Tesla. Lithium LFP batteries are regarded as the safest and most stable battery chemistry with the longest life of up to 10,000 cycles, also they do not use any heavy metals.

The Tesla Powerwall 2 on the other hand is weather rated and can be installed outside plus has a built in thermal cooling system, where as the Sonnen battery system will not tolerate higher temperatures above 45 degC and must be installed inside a protected area such as a garage.

See how the batteries compare in out complete solar battery comparison article

Sonnen battery compared to the Powerwall 2 and other leading battery storage systems.

Sonnen battery compared to the Powerwall 2 and other leading battery storage systems.


Inverter Power

Sonnen battery inverters in both the ECO and hybrid models have a limited continuous power output power of 3.3 kW with a maximum peak output also rated at 3.3kW. Most homes basic energy consumption will be much less than 3.3kW on average so this should not be a big concern, unless you regularly use very high power appliances such as electric car chargers or multiple air-conditioners.

The plus side to having a relatively lower power output is that the battery is not ‘worked hard’ meaning the cell charge/discharge rate is low in comparison to the available capacity. This means the battery cells should last much longer and operate at higher efficiency. Also during hot weather the cells with not heat as fast which can also prolong battery life.


Video from Sonnen - The sonnenBatterie intelligently controls how energy is used to power homes - even when the grid is down. Robust self-learning software manages solar generation, battery storage and smart plug technology to cost-effectively meet household energy needs.

10 year / 10,000 cycle Warranty

Like most other reputable battery supplies the sonnenBatterie warranty comes with a 10 year warranty but it beats most others in that it also covers 10,000 charge/discharge cycles to 80% retained capacity. This is very impressive and only high quality lithium cells with robust monitoring and balancing could achieve this. Ten thousand cycles is huge and no doubt the ten year period will come before this numberof cycles is ever reached, even with 2 cycles per day this would take about 13.7 years.

However like most warranty conditions the battery must be maintained in a relatively controlled environment but the warranty document does not specify a temperature range or so it is not clear exactly what conditions are covered.

The warranty states the battery must be connected to the internet to receive software updates or it will not be covered by the warranty. The exact wording is “If the sonnenBatterie is not connected to the internet, or software updates are not performed, sonnen does not warrant that the sonnenBatterie will be free from defects or faults.”

See the full warranty document here (Australian Warranty)

Summary Wrap up

Sonnen battery systems are a premium offering from one of the world’s largest and most experienced battery manufacturers. Sonnen systems have proven performance and a good warranty which puts them in the same league as both Tesla and LG chem. The Sonnen systems using the premium Sony cells may be expensive compared to others but they will no doubt outperform and outlast most other battery systems on the market provided they are kept in a relatively controlled environment. The warranty document is a little light on details but with no less than 80% of the original rated capacity remaining after the 10 year warranty period makes this one of longest lasting batteries on the market.

The limited inverter power might be a concern for heavy power users but for most households it should be more than enough. If you have regular blackouts in your area or require a UPS then this is not the system for you; although if blackout are rare then the sonnenBatterie is a great choice.