What solar battery has the greatest capacity? LG vs Sonnen

Published: 13 February 2019

Looking for the best solar battery with the greatest energy storage capacity? Find out how LG’s solar battery compares to Sonnen’s. We look at warranty, price, specs and dimensions to find out which battery is best.

The energy storage industry is constantly evolving and the leading companies in the market are struggling to get a bigger slice of the pie. Considering this, it can be difficult to decide on the best solar battery with the greatest storage capacity. In this article, we’ll help you weigh up your options between LG and Sonnen.

In this market competition there are three big players: Tesla, LG Chem and Sonnen. So on this occasion we will examine a Korean vs a German company: LG Chem and Sonnen.

LG Chem is a large subsidiary of LG Electronics based in South Korea and offers a wide range of energy storage solutions to the market known as the LG Chem RESU models.  Their top and most recent model is the RESU10H lithium-ion battery.

Meanwhile, Sonnen is one of the greatest battery manufacturers in Europe and is headquartered in Germany.  The company released its 9th generation Sonnen Batterie Eco available in multiple power sizes.

Let’s analyse each of these products to see which is the winner in this battery showdown!

Best solar battery choice for warranty

Warranty is an important factor to take into account. 

LG Chem RESU 7H and 10H products guarantee that the battery will retain at least 60% of its nominal energy output for 10 years, or for a minimum energy throughput from the battery, whichever comes first. 

According to this statement, the LG Chem RESU 10H model that has nominal energy storage of 9.8kWh ensures that the product will be able to store at least 5.88 kWh by the end of the 10 years or provide 27.4MWh of energy throughout.

Meanwhile, the Sonnen Batterie Eco 9.43/10 has a nominal battery capacity of 10 kWh (similar to the LG Chem product) and guarantees that the product will maintain at least 70% of its capacity to hold a charge or run at least 10,000 cycles, whichever happens first. 

This is a point for Sonnen!

Best solar battery choice for price

Competition between energy storage manufacturers has intensified since Tesla started reducing prices to compete and make energy storage more attractive for residential uses.

LG Chem has followed this trend and has been able to establish the average cost of LG Chem RESU 10H at around $7,000. Considering this is the residential product with a higher energy capacity, it gives you an idea of affordability with lower size models. 

On the other hand, Sonnen has not followed this trend. The Sonnen eco 9.43 for instance, can be found in price ranges starting from $11,000. 

It is very important to know that this is the price after the South Australian subsidy is applied. A price that would probably not pay for itself within the 10-year warranty. 

That is definitely a point for LG!

(Disclaimer: Even though we aim to provide the most accurate information on our Nectr blog, the prices mentioned above may vary depending on your location, solar provider or other reasons. Please ask your solar installer for an accurate quote). 

Most conveniently sized home batteries

A big flaw of the Sonnen battery is the amount of space required. 

According to LG Chem RESU 10H datasheet, the energy storage is 90 cm height, 74 cm in width and 20 cm in depth and weighs 97 kg. 

On the other hand, Sonnen 9.43 10kWh battery, is 186 cm height, 67 cm wide, and 23 cm depth. 

Also since the battery changes as you add more cells of 2.5kWh capacity, the weight also changes. But for the 10kWh model, the estimated weight is around 154 kg! 

This is another point for LG!

Best solar battery choices

The LG Chem RESU 10H is a lithium-ion battery designed to be connected at 400 VDC nominal voltage and a maximum voltage of 520 VDC

High voltages are always desirable since they mean that to transfer the same amount of power, less electrical current is required, which also means less power loss.

In this sense, the maximum charging current is 11.9A at 420V and maximum discharging current is 14.3A at 350V. 

Also, the battery nominal capacity is 9.8kWh, but its usable capacity is 9.3kWh. This translates into a maximum depth of discharge of 95%. 

Moreover, the LG RESU models are designed to fit both indoor or outdoor environments without any additional enclosure, and compatible inverters with the battery are from Fronius, Sungrow, SMA and SolarEdge. 

Continue reading here: All You Need to Know About LG Chem Compatible Inverters

Meanwhile, the Sonnen model works with a lithium iron phosphate battery at a nominal voltage of 48VDC

The depth of discharge of the battery is 90% which means that from a 10kWh nominal battery capacity model you will only be able to use 9kWh and the battery is only suitable for indoor spaces, meaning an additional expensive enclosure is needed for outdoor purposes.

An important difference with the LG Chem RESU models is that Sonnen offers an all-in-one solution that includes a storage system and inverter. 

In other words, you do not need to purchase an inverter to convert to AC; an important difference. 

However, keep in mind that maximum power capacity is only 3.3 kW for all 9th generation models, which is not a lot.


We have found that the warranty offered by Sonnen is better than the one from LG since Sonnen is guaranteed to remain at least with 7kWh while LG is warrantied with 5.88kWh by the end of the 10 year period. 

Regarding dimensions and weight, which can deeply influence transport costs, they are definitely much better with the LG option.

If we refer to the specs, we notice that the LG product has a better DOD than Sonnen and that it can be placed in outdoor or indoor conditions. 

Maybe we could consider the fact that LG needs to be coupled with specific top inverters a limitation, while Sonnen offers an all-in-one solution. 

However, we must also evaluate the AC power output that we want to have available. Sonnen’s 9th generation products limit their AC power output to 3.3 kW while LG has no limit on this aspect since it is established by the selected inverter. 

Here a decision must be made as to whether it suits you to have 3.3 kW AC output or not.

Maybe the most determining point is price, as it usually is. 

Sonnen offers a really good quality product, but LG is also doing so. The question is if the extra price is worth it? 

Probably not, since the LG product will pay for itself much faster than Sonnen’s, you will not be capped at 3.3kW, and you will still have access to enough energy to power your appliances at night while using solar energy.

For more information about solar batteries visit our product page!

Next Steps…

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