Sonnen Battery Review
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Company background
Sonnen founded in 2010, is a leading German 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 has heated up over the last few years, with many low-cost battery systems entering the market. To help reduce pricing and become more competitive in other markets, Sonnen began manufacturing and assembling systems in California in 2015 and in South Australia in 2018.
Sonnen battery Options
Sonnen offers two different battery systems suited to different applications. The Sonnen EVO, which replaced the previous ECO model, can be retrofitted to homes with an existing solar installation. The other option is the Sonnenbatterie hybrid, an all-in-one system that includes a solar inverter.
Sonnen EVO - AC Battery
The SonnenBatterie ‘EVO’ system is much like the Tesla Powerwall 2, being that it is an AC battery with a built-in power inverter. Total storage capacity is 11 kWh with 10 kWh usable capacity. The power rating is relatively high at 5.0kW continuous and 7kW peak (surge) output, making it an ideal retrofit option for homes with an existing solar system requiring backup power.
Sonnen EVO battery specifications
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 system 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 5kW 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.
Download the Sonnen EVO battery specification datasheet here.
Sonnen Hybrid - All-in-one System
The SonnenBatterie Hybrid is the all-in-one hybrid system with a solar inverter, charger and battery in one simple unit. The hybrid option has a maximum solar PV capacity of 6.4kW and a nominal inverter rating of 5.5kW (3 phase). However, the battery inverter is still limited to 3.3kW for battery charging and discharging.
Download the full SonnenBatterie Hybrid specification datasheet.
For larger residential or commercial (3 phase) buildings requiring more energy storage, like other battery systems the SonnenBatterie can also be set up in a ‘cluster’ with a maximum of 45kWh total capacity (3 x 15 kWh).
Limited Backup Power
The Sonnen Hybrid system 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 needs to be installed. 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 back up 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 a 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 more powerful 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 EVO has a slightly smaller total capacity of 11kWh. The second is Sonnen uses Lithium Ferro Phosphate or LFP battery chemistry, as opposed to the Lithium NMC chemistry of Tesla. Lithium LFP batteries are the safest and most stable battery chemistry, with the longest life of up to 10,000 cycles. Also, they do not use any rare-earth or heavy metals such as Cobalt.
The Tesla Powerwall 2 is weather-rated, can be installed outside, plus has a built-in thermal cooling system that enables a wide operating temperature range. The Sonnen battery system, on the other hand, is a little more limited and will not tolerate being exposed to the elements or temperatures above 45 degC, so it should be installed inside a protected area such as a garage. See how the batteries compare in our complete solar battery comparison article.
Sonnen battery compared to the Powerwall 2 and other leading battery storage systems.
Inverter Power rating
The Sonnen battery 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 EVO model, on the other hand, has a slightly higher continuous power rating of 5kW and a surge rating of 7kW, which is similar to most other battery systems of this size.
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.
Inside the Sonnen battery
The early Sonnen battery modules use LFP or LIthium Ferro phosphate cells manufactured by Sony and are some of the most reliable and longest-lasting cells available. However, they were prohibitively expensive. More recently, Sonnen switched to more cost-effective LFP battery modules made by Pylontech, one of the leading Chinese Lithium battery manufacturers. Interestingly, both the Sony and Pylontech batteries performed exceptionally well in the ITP renewables battery test centre, which conducted extreme battery cycle tests for many years to test durability, performance, degradation and lifespan. In fact, only the Sony and Pylontech batteries passed the long-term testing program.
ITP renewables battery test centre results
The 9.53 Hybrid uses the second generation LFP2 (Pylontech) modules, and the EVO system uses a sonnenModule 4 which was developed in-house by the Sonnen engineers. All Sonnen systems are backed by an impressive 10-year or 10,000-cycle life warranty (details below).
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 number of 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.”
Download the full Sonnen warranty document AU (Australian Warranty)
Download the full Sonnen warranty document (USA Warranty)
Summary Wrap up
Sonnen battery systems are a premium offering from one of the world’s largest and most experienced battery manufacturers. The proven performance and great warranty place them in the same league as industry leaders Tesla and BYD, although some argue they are even better.
The warranty document is a little light on details, but it guarantees no less than 80% of the original rated capacity remains after the 10-year warranty period or 10,000 cycles, making this one of the longest-lasting batteries on the market.
The limited inverter power on the hybrid model will be an issue 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, this is not the system for you. Although, if blackouts are rare, the Sonnen battery Hybrid or EVO is a great, reliable choice.
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