If you’re looking at ways to make your home more energy-efficient, then chances are you’ve considered a solar panel setup, complete with a lithium ion battery backup system.
This versatile storage option lets you harness the sun’s power for later use when your panels are producing more energy than your house can process. The batteries store the surplus for use on cloudy days, evenings, and any other time there’s a shortage of sunlight.
Without a battery storage system, you will either need to connect your home to the main power grid or maintain a different backup energy supply for when your panels aren’t producing.
In short, owning a home storage battery system connected to a renewable energy source makes it possible to slash your electricity costs and approach net-zero energy use. However, these batteries aren’t without their own environmental costs.
- Lithium ion batteries: sustainable solution or ecological disaster?
- Overall Winner
- The best lithium ion batteries – in depth reviews
- Are lithium ion batteries worth it? Looking towards the future
Lithium ion batteries: sustainable solution or ecological disaster?
The harsh reality is that lithium ion batteries have some serious limitations for the planet. Not only do these batteries have relatively short lifespans, but they can also be a challenge to dispose of. As things stand today, just 5% of spent batteries are properly recycled. This is shaping up to become a severe problem, as industry analysts predict that more than 10 million metric tons of lithium ion batteries will end their functional lifespan by 2030.
Even worse, these batteries typically contain minerals like nickel and cobalt that are mined in highly destructive ways. This can lead to air and water pollution, habit destruction for endangered species, and higher rates of cancer and other health problems for the people forced to mine them.
This means that it takes some research to make an environmentally conscious decision about which lithium ion batteries to invest in to power your green home. Below is an analysis of some of the top options in the lithium ion battery industry and our recommendations for the most sustainable choices. You can read more about our ranking methodology here.
Below is our top overall pick for the best lithium ion battery for powering your green home. Keep scrolling to read our in-depth reviews on the winner and three runners-up.
Best overall lithium ion battery – Sonnen Eco
You might pay more at the onset for this German-engineered rechargeable battery, but the Sonnen Eco brand impresses us with its all-in-one system that comes complete with an inverter and management software. You can choose from a range of battery sizes, and Sonnen offers one of the best guaranteed end-of-life capacity ratings (88%) for its ten-year warranty period.
The best lithium ion batteries – in depth reviews
Sonnen Eco (Overall Winner)
Highlight: This AC battery offers a range of sizes, an integrated setup for maximizing efficiency, and lithium iron phosphate batteries (LFP) known for their high power rating, safety features, and longer lifespan.
Price: Starts at $9,950 before installation
The Sonnen Eco Battery comes from a German-based company that sells fully integrated power systems for the smart home. This means your AC battery will come with an inverter and smart energy management software for a more seamless setup process and an easier way to maximize the efficiency of your solar panels.
The company offers a range of battery sizes that include usable capacity power spectrum from 5 kWh to 20kWh. They have backup power capabilities, meaning that you can rely on your Sonnen Eco to run your home when the grid goes down.
Unlike the other batteries listed here, the Sonnen Eco is a lithium iron phosphate (LFP) battery. These batteries are known for their high power rating, safety, and a longer lifespan that makes it one of the most eco-friendly options available. By the company’s estimation, a Sonnen battery has an overall lifespan of around 8 to 13 times longer than traditional residential energy solutions.
From a performance standpoint, these batteries come with a ten-year warranty and an impressive guaranteed end of life capacity of 88%.
As a brand, Sonnen has gained recognition as a leader in environmental sustainability. In 2017, it became the first energy storage company to receive the Zayed Future Energy Award in the “Small to Medium Business” category.
LG Chem RESU
Highlight: While an industry leader for clean energy production and innovation, LG Chem RESU batteries offer only a 60%guaranteed end of life capacity ratings.
Price: Starts at $6,000 before installation
The South Korean-based company LG Chem boasts a 72 ESG (Environmental, Social, and Governance) ranking, and its DC-coupled RESU lithium-ion batteries range in power from 3.3 to 13 kWh. It’s most commonly used for storing energy from solar panel systems and will purportedly last up to ten years. However, this lifespan is guaranteed only at 60% capacity, which is lower than its competitors.
According to the company’s 2017 sustainability report, LG Chem is the first Korean chemical company to make a goal of becoming carbon neutral by 2050 with its plan to implement 100% renewable energy use at all business sites worldwide. To meet this standard, it plans to suppress emissions in 2050 to just 10 million tons (equivalent to the company’s 2019 levels), which will require the company to reduce a projected 30-million tons of emissions at the current business growth rate.
LG Chem also plans to implement a strategy for 100% transparency and traceability throughout its supply chain, especially regarding problematic raw materials like cobalt. It is also mandating the adoption of a “Landfill Zero” certification policy at new business sites, which would mean that more than 90% of all waste products are recycled. This standard has already been reached at a Michigan manufacturing plant.
Likewise, LG Chem will expand its use of PCR (post-consumer recycled) plastics from its current level of 60% to 85%, while also increasing the use of biodegradable plastic materials and recycling more of the raw materials (like cobalt) contained within its batteries.
While these goals sound great, it’s important to note that they focus more on LG Chem’s future projections rather than what the company is accomplishing right now.
Tesla Powerwall 2
Highlight: Tesla’s electric cars get most of the media attention, though its home batteries show potential too. Our biggest problem with this company is that most of its environmental promises are theoretical at this point.
List Price: $6,700 before installation and solar inverter
Though better known for its foray into the electric car market, Tesla is also selling its lithium ion batteries for home use. The Powerwall 2 is an AC battery with an energy capacity of 13.5 kWh and 90% round trip efficiency. It can be monitored in real-time through the Tesla App, which lets you optimize settings to maximize energy storage for better sustainability.
You can mount the unit indoors or outside, and the company boasts that it’s possible to scale your system up to ten units to maximize your home’s energy storage capacity. Each unit comes with a ten-year warranty but offers only a mediocre 70% lifetime capacity. Note that you will need an additional solar inverter to use it with solar panels.
The Powerwall 2 offers one of the best cost to capacity ratios in the industry. However, Tesla has a less-than-impressive ESG rating of 33. This is due in part to the reasons why Tesla entered the home battery industry in the first place—an excessive supply of electric batteries for cars it needed another market for.
Even so, Tesla has a relatively positive environmental track record. The company’s 2019 Impact Report shared that the company provided disaster relief financial assistance in areas impacted by hurricanes and forest fires throughout 2018 and 2019, and delivered temporary clean power solutions to more than a dozen critical infrastructure sites through a combination of solar panels and Powerwalls.
The company also plans to offer onsite recycling for its batteries at the main manufacturing factory to reduce the environmental issues associated with their short lifespan. This factory is currently 50% fossil fuel-based, and Tesla is currently working towards making it 100% carbon neutral through a 70-megawatt solar farm.
Tesla also claims to be committed to sourcing responsibly produced materials through “an environmentally responsible and humane supply chain,” particularly by collecting data from suppliers through the Responsible Minerals Initiatives Cobalt Reporting Template. Saying that, it acknowledges that it purchases most of its raw materials from suppliers and sub-suppliers, which makes it challenging to trace them back to their sources.
If Tesla has a reasonable basis to assume a supplier is going against its environmental standards, it will purportedly transition away from that supplier. What this means for day-to-day operations, though, is hard to say.
Pika Energy Harbor Smart Battery
Highlight: Pika Energy Harbor’s high-end batteries make it possible to power your home fully on solar power, and it boasts 96.5% round trip efficiency throughout its range of battery sizes.
Price: Starts at $12,000 before installation
Pika Energy offers a range of lithium ion batteries that are specifically designed to be paired with solar panels. They range from 10.1 (Harbor 3) to 20.3 kWh (Harbor 6). The company claims to offer “the most powerful and flexible smart battery available to homeowners,” and each model is designed to give you extended backup power so that you maximize the efficiency of your solar panel setup.
Harbor batteries have a “black-start” capability that lets you charge them from empty through solar power alone—no connection to the grid necessary. This makes it possible to produce and use your own solar energy, even when net metering isn’t available. Homeowners will also appreciate that the Harbor battery system doesn’t require extra hardware to install.
These batteries boast a round-trip efficiency of 96.5%, and include a ten-year warranty. However, Pika doesn’t specify its battery’s minimum functionality threshold throughout the warranty as its competition does.
Pika Energy has minimal published information about the environmental impacts of the production process for its lithium ion batteries. We did find that the company was awarded funding in 2015 to increase the efficiency of its wind turbines for powering its manufacturing plants.
However, this system’s flexibility and functionality for the home user who wants to minimize (or even eliminate) their reliance on the grid earn it points from our perspective. It’s also an advantage that you can combine multiple batteries to supply more of your home’s energy needs.
Are lithium ion batteries worth it? Looking towards the future
When you look closely at the environmental consequences of lithium ion batteries, it’s easy to wonder whether adopting this technology is worthwhile from a sustainability standpoint.
While there is lots of room for progress to make this technology truly eco-friendly, it’s clear that they offer a valuable alternative to fossil fuels. Lithium ion batteries tend to have high environmental costs upfront due to their mining and manufacturing processes. Still, they start to become more eco-friendly the longer you use them by reducing your home’s reliance on coal or natural gas.
As each battery option on this list is designed to last at least a decade, using lithium ion batteries will make a significant difference in your home’s carbon emission levels over the long run.
Looking toward the future, there is hope that an eco-friendly alternative to lithium ion batteries could be found by manufacturing them out of aluminum instead. Recent breakthroughs have doubled the material’s potential energy density. This opens the door for large scale applications without the problems associated with lithium ion like rare mineral extraction and recycling challenges.
Though initial reports seem promising, more research is necessary before we can say conclusively whether aluminum-fueled battery power is the path of the future.
All this to say, if you have a solar panel setup and frequently find your system generating more power than your house can use at once, it’s likely in your best interest to invest in a lithium ion battery setup. You’ll increase the amount of energy you can harness from the sun and will reduce your reliance on polluting energy sources in the process.