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Is the LG Chem RESU battery right for your home?

Avatar for Ben Zientara
Published on 11/13/2019 in
Updated 03/11/2020
The LG Chem RESU Battery

In Short: The LG Chem RESU battery is a lithium ion battery that can keep your home running even if the grid goes down. Since 2013, the LG RESU battery is a proven product with a solid track record. It’s also used by some of the biggest solar installers in the country to provide backup power for their solar systems.

In the crowded home energy storage field, the LG Chem RESU home battery stands out for its relative longevity; it was initially launched in 2013 and brought to the North American market in 2017. During that time, LG has become the top market player in energy storage, and U.S. installers like Sunrun and Vivint Solar offer home battery storage systems based on the LG Chem battery.

Like the Tesla Powerwall battery, the LG Chem RESU needs to be paired with a compatible solar inverter in order to charge from a solar installation. There are several storage inverters available on the market, including the SMA Sunny Boy Storage and the SolarEdge Storedge.

We’ll go through all the details below, but for those of you who like lists that sum up more complicated writing:

  • The LG Chem RESU battery can keep your lights on if the power goes out
  • It should last 10 years, but LG’s warranty is not as good as Tesla’s.
  • An LG Chem RESU 10-kWh battery will set you back around $8,500
  • It probably won’t ever pay off its cost, but the peace of mind you get from a battery backup has no tangible financial value.

What are the benefits of the LG Chem battery?

The most important benefit of energy storage is keeping your refrigerator running and the lights on if the electric grid goes down. The peace of mind that comes with using solar power in a blackout is intangible, so you need to decide what it’s worth to you.

A secondary benefit is to be able to charge the battery with solar power during the day and use the stored energy in the evening. This can help avoid the costs of utility company tactics like demand charges and time-of-use rates that can make a traditional grid tied solar system less financially viable.

LG, perhaps more than other companies, can promise benefits like these because they have a longer track record of successful battery deployment. Like we said above, LG batteries have been paired with solar panels since 2013, with great success.

How many years will the RESU battery last?

Like most other home battery systems based on lithium-ion technology, the LG Chem RESU10H battery is warrantied to last for at least 10 years, but the details matter. While the LG Chem RESU battery carries a 10-year warranty protection, it guarantees different performance over that time than other lithium-based batteries.

The specifics of LG Chem’s 10-year battery warranty

The warranty doesn’t include explicit protections from defects in materials and equipment, which is a fairly major oversight. The warranty implies that LG will repair or replace the battery if it’s found to be defective, but that doesn’t meet a very high standard. It would be better if LG explicitly guaranteed protection for faults in materials and workmanship for 10 years.

LG Chem’s warranty does promise that its RESU batteries will maintain at least 60% of their initial rated energy storage capacity after 10 years OR before the battery has been used to provide 22.4 megawatt-hours (MWh) of electricity.

That distinction is important, because if you’re charging and discharging the battery daily, you’ll probably run through that amount of MWh sooner than 10 years. To spread 22.4 MWh over 10 years, you’d have to ensure the batteries discharge an average of only 6.14 kilowatt-hours (kWh) per day, which is 62% of their capacity.

This should be fine for most people, as daily cycling of the battery isn’t necessarily the plan. Talk to a licensed installer to find out whether you should expect to use more than 6.14 kWh of battery storage per day.

The LG warranty vs. other solar batteries

This 10-year warranty sets the LG RESU battery part from older varieties of deep cycle battery banks that have been used in solar installations for decades. Those batteries, based on lead acid and other technologies, typically carry warranty coverage from only 12-24 months.

If properly cared-for, these deep-cycle batteries usually last longer than their warranty periods — between 4 and 8 years depending on the technology. That’s not a long lifespan, but considering these cost about one-third as much as lithium batteries like the LG RESU, it’s a trade-off people have been making for years.

A more direct comparison can be made between LG’s battery and the Tesla Powerwall 2. Tesla’s warranty for its 13.2-kWh battery includes explicit language that the battery will be “free from defects” for 10 years. As for charging capability, the warranty says the battery will retain at least 70% of its ability to store energy during the 10 year period.

Tesla guarantees that performance for 10 years and unlimited cycles if you charge the battery exclusively with solar energy and use it as a backup. If you use the Powerwall to draw from the grid or charge your electric vehicle, they guarantee 37 MWh of aggregate throughput. That’s 65% greater allowance than the LG Chem battery.

Importantly, Tesla requires you get your Powerwall connected to the internet and register the equipment with them in order to retain the full 10 year warranty.

How much does the LG Chem RESU battery cost?

As of late 2019, the LG Chem RESU10H can be bought from online suppliers at a cost of between $5,900 and $8,000. That’s down from an MSRP of $8,750.

But you can’t just buy one of these things, slap it on the wall, and plug a cord into it. It’s important to have a battery like this installed by a professional solar installer or electrician, who is authorized to perform the installation and do repairs. In fact, LG’s Warranty requires warranty claims to go through the installer.

That means you’ll be paying someone to install the battery, probably at a cost of about $1,500. A complete installation of the LG Chem RESU10H will likely set you back around $8,500, but you might be able to get a better deal if you have one included in the price to install new solar panels on your roof.

You could also choose the Sunrun BrightBox or Vivint Battery Backup system, which include the LG batteries in them as part of a full-service package. Prices for those two should also be around $8,500.

Is the LG Chem RESU battery worth it?

Like we said above, whether this battery is worth it to you depends on the price you put on peace of mind. If you absolutely can’t bear the thought of suffering through a power outage in the dark, then the LG battery is a no-brainer. And no one could blame you, with Californians now seeing “planned outages” of more than a day or two on a regular basis.

The only way the LG battery becomes financially worth it is if you use it to avoid time-of-use or demand charges. In that case, you’d have to be saving over $.50/kWh on every kWh of storage in order to make it worth it over the 10 year lifespan of the battery.

No place on earth has a difference of $.50 between its on- and off-peak electric rates, so the cost of the LG battery will basically never be repaid.

However, if you look at this more like a balancing act, between the “peace of mind” benefits and the tangible financial benefits, it might start to look better. Especially if you live in California.

Last modified: March 11, 2020

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