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LG Chem RESU battery: the complete review

LG is a leader in the home electronics industry and manufactures some of the most popular panels featured in quotes to shoppers on the EnergySage Solar Marketplace. Now, they’ve entered the U.S. home energy storage market with the launch of their LG Chem RESU battery line.

But how does LG Chem's RESU battery pack measure up against all the other home energy storage options? Read on to learn more about the LG Chem solar battery’s cost, technology, and warranty coverage.

What is the LG Chem RESU?

LG’s lithium ion RESU battery is a home energy storage solution that can be paired with a solar panel system. According to the company, the RESU  can be used both to maximize consumption of solar energy at home, rather than sending it back to the grid, and also functions as a source of backup power in the event that the grid goes down. However, while the RESU has some backup power capabilities, it isn’t designed for off-grid use.

The LG Chem RESU comes in a range of sizes from 3.3 kilowatt-hours (kWh) to 9.8 kWh. U.S. prices for the RESU aren’t currently available, but prices for the technology in other markets indicate that it will be similar to other home batteries like the Sonnen eco and Mercedes Benz home battery.  

How the LG Chem solar battery works

The LG RESU is an ideal pairing for solar panel systems, especially if your utility has reduced or no net metering, time-of-use rates, or demand charges. Installing a solar storage solution like the RESU allows you to maintain a sustained power supply during the day or night.

As with other home energy storage products, the LG Chem battery pack is sized for day-to-day use at your home, and is usually paired with a home solar panel system. When your solar panels produce more electricity than you can use in your home, the excess is stored in the battery pack instead of being sent back into the electric grid. Later, when your panels aren’t producing enough electricity, you can use the electricity stored in your LG solar battery instead of having to buy it from your utility.

Normally, this process happens over the course of a day: when the sun is high in the sky and your solar panels are producing more electricity than you can use, the surplus energy is stored in your battery. As the sun goes down and your solar panel production decreases, you draw on the electricity that you stored during the sunniest part of the day. Essentially, home batteries like the one manufactured by LG help you balance out your electricity production and usage over the course of the day.

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Can you go "off the grid" with an LG Chem RESU and solar?

Installing a solar-plus-storage system at your home is a great way to take control of your electricity bill, but it doesn’t mean that you’re completely disconnected from your utility. Going "off the grid" with solar batteries is actually a more expensive and complicated proposition than you might think. A single LG home battery will only provide backup power for a few hours – not nearly enough to cover you if you have an entirely cloudy day, let alone several days or weeks of inclement weather.

What is LG's battery warranty, and how long does the battery last?

A 3 kWh RESU can help power your home for a few hours with a single charge. In most cases, homes with an LG Chem home battery will charge and drain the battery every day. The RESU comes with a 10-year warranty that assumes your battery is used for daily charging and draining. During that time, if the battery malfunctions or loses more than 40 percent of its storage capacity, it is eligible for replacement under LG’s battery warranty.

LG’s lithium ion battery technology is similar to other rechargeable batteries both large and small: as time goes on, the battery loses some of its ability to hold a charge. Think of how the battery life of a brand-new smartphone compares to one that is a few years old. As you continually charge and drain your phone’s battery, it starts to lose some of its ability to hold a charge.

The battery life of your RESU battery will deteriorate in the same way. That isn’t an indicator of a product flaw – all batteries lose some of their ability to hold a charge over time, whether it’s an electric vehicle battery, a home energy battery, or a rechargeable AA battery. LG’s guarantee that the battery will retain at least 60 percent of its capacity over the course of the warranty shows that the company stands by its product more than other solar battery manufacturers (such as Tesla and Sonnen) that don’t have a warranty related to storage capacity.

How much does the LG Chem RESU cost?

While a full set of list prices for the LG Chem RESU aren’t yet available in the United States, distributors are pricing the 9.3 kWh RESU at $6,000 - $7,000. This price doesn’t include the inverter for the battery or the cost of installation. The inverter can add another $2,000 to $3,000 in equipment costs, and installation can range from $1,500 to $3,000+ (depending on the specifics of the installation).

If you want to install the RESU as part of a solar-plus-storage system, battery costs are just one part of the equation. An average 5 kilowatt (kW) solar energy system costs anywhere from $9,000 to $15,000 depending on where you live and the type of equipment you choose. That may sound like a lot of money, but installing a solar-plus-storage system can be a worthwhile investment – and you can save significantly on installation costs by installing both technologies at once.

Solar battery economics depend on a few different factors. Whether or not the LG Chem RESU makes sense for you is determined by the way that your electric utility structures its rates, as well as your reasons for installing a solar battery.

In some cases, depending on where you live, you may have access to financial incentives that can reduce your home energy storage installation costs. If you live in California, you could get a cash rebate that covers many of your home battery costs through the Self-Generation Incentive Program (SGIP). Other states (like Massachusetts) are in the early stages of evaluating potential energy storage incentives as well. Most recently, Maryland established a solar battery tax credit worth $5,000 to $7,500.

Should you install an LG Chem RESU or other solar battery?

Solar batteries are a fairly new technology for homeowners. While they offer significant benefits for some, they aren’t always a necessary investment. If your utility offers net metering, installing a solar battery won’t save you money. However, if you install a solar panel system in an area with time-of-use (TOU) electricity rates, no net metering, or significant demand charges, a solar battery could be a good choice for you.

Where to buy the LG Chem solar battery

Currently, the LG Chem RESU is being offered through an exclusive partnership with solar installer Sunrun. It will soon be available through other solar installers and approved LG Chem battery dealers.  Whether you want to install an LG RESU or other home battery pack, you will most likely need to work through a certified installer. Adding energy storage technology to your home is a complicated process that requires electrical expertise, certifications, and knowledge of the best practices required to install a solar-plus-storage system correctly.

A qualified EnergySage-approved company can give you the best recommendation about the LG home battery and other energy storage options available to homeowners today. If you are interested in receiving competing installation quotes for solar and energy storage options from local installers near you, simply join the EnergySage Solar Marketplace today and indicate what products you’re interested in your profile’s preferences section.

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