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Sonnen eco: the complete review

Last updated 3/1/2019

Sonnen is one of the biggest names in energy storage technology, and in 2016 the company announced a new battery designed for home use: the sonnenBatterie eco. The eco is a fully integrated energy storage system that includes an inverter and smart energy management software. Property owners with solar that install a home battery like the eco are able to store excess solar electricity for use later in the day. As a result, properties with solar-plus-storage can increase their total monthly savings in certain markets

What is the sonnenBatterie eco?

Sonnen describes the lithium-iron-phosphate eco battery as an "all-in-one residential solar battery solution.” It offers various grid-tied functions, including increasing household solar self-consumption and managing time-of-use electricity rates. The battery also has some backup power capabilities. 

The eco comes in a range of sizes from 5 kilowatt-hours (kWh) to 15 kWh. While the company's website doesn't have pricing information, prices from solar equipment providers start around $10,000 (for the 5 kWh eco) and go as high as around $23,000 (for the 15 kWh eco). Note that the list price does not include installation costs, which can add a significant amount to the final pricetag. 

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How does the Sonnen eco work?

The sonnenBatterie eco 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 eco allows you to maintain a sustained power supply during the day or night.

As with other energy storage products, the sonnenBatterie 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 Sonnen home 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 Sonnen 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, the eco helps you balance out your electricity production and usage over the course of the day.

Can you go "off the grid" with a Sonnen eco 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. Most home batteries, including the eco, only have enough capacity to store a few hours of electricity. That being said, some of the larger eco batteries could serve as temporary backup when the grid goes down if you have a solar panel system to provide power. 

What is the Sonnen eco warranty, and how long does the battery last?

A 5 kWh eco can help power your home for a few hours with a single charge. In most cases, homes with a Sonnen home battery will charge and drain the battery every day. The eco comes with an unlimited 10-year warranty that assumes your battery is used for daily charging and draining. Sonnen also guarantees that the battery will maintain at least 70 percent of its capacity to hold a charge during that time. 

Sonnen 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 eco 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. This is why Sonnen offers a warranty that guarantees a certain amount of storage capacity.

How much does the sonnenBatterie eco cost?

The Sonnen eco has a starting list price of around $10,000, which includes the integrated inverter and energy management software. However, the price doesn’t include installation, which can increase your costs by thousands of dollars. 

If you want to install the eco 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. Solar battery economics depend on a few different factors. Whether or not the sonnenBatterie eco 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 most 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.

Should you install a Sonnen eco 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, or if you are interested in having sustainable backup power, a solar battery could be a good choice for you.

Where to buy the Sonnen eco

Sonnen's eco battery is currently available through the company's installer network in the U.S. Whether you want to install a sonnenBatterie eco 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 Sonnen 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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