The backup battery choice you didn’t know you had: li-ion, or vanadium flow?
Whether it’s to keep the lights on after a natural disaster or just to avoid peak energy rates, more people than ever are adding battery energy storage to their home solar systems. With some 45% of home solar customers saying yes to home batteries last year, the big question isn’t whether or not to get one – it’s what kind to get.
Two options stand out: lithium ion, and vanadium flow. Here’s the information you need to make the right choice.
SKIP THE STORY: get me prices on both types of batteries.
Lithium-ion or “li-ion” batteries are the batteries you’re probably most familiar with. They’re used in most laptops, smartphones, and EVs – and for good reason!
Over the last few decades, billions of dollars have been poured into li-ion R&D, and the resulting batteries are energy dense, almost entirely recyclable, and readily available, with literally millions of li-ion batteries in the market today.
That sort of market ubiquity and like-for-like competition among vendors and manufacturers has driven per kWh costs down continually. And those lower costs? They’re driving adoption in big solar markets like California, Texas, and Hawaii, where between 68 and 100% of residential solar quotes have home backup batteries “attached,” and Tesla – thanks to the slick new Powerwall 3 and its integrated solar inverter – is the most quoted brand.
Most quoted home solar batteries
As good as they are, li-ion batteries aren’t perfect. Li-ion batteries degrade over time, losing capacity with use and needing to be replaced after 10-15 years. And, while the risk of a lithium battery fire is increasingly and exceedingly low, it’s also very real – leading to intense fires that are difficult to put out with conventional fire-fighting methods.
Vanadium flow batteries address both of those shortcomings, offering 20-30 years of usable service life without degradation and with little (or, depending on who you believe, zero) chance of the sort of “thermal runaway” that leads to li-ion battery fires.
Flow battery diagram
If you’re not familiar with flow batteries, the Wikipedia page is a great first learning step (I hope – I’m still wrapping my brain around them). Once there, you’ll find that a flow battery works kind of like a fuel cell – charged ions pass through the membrane, causing electrons to flow through an external circuit, generating usable electricity.
The energy capacity (kWh) of a flow battery is determined by the volume of the electrolyte fluids in the tanks (bigger = more), while the power output (kW) depends on the size of the electrochemical cell stacks.
That is, of course, to say that a comparable vanadium flow battery will be significantly bigger and more complex than a li-ion solution. That added complexity, combined with the relative rarity of vanadium flow batteries on the market, mean that the same economies of scale and manufacturer/vendor competition haven’t acted to drive costs down in the same way that they have in the li-ion space.
Spec + price comparison
| Battery | Usable Capacity (kWh) | Continuous Power Output (kW) | Round‑Trip Efficiency | Average Price per kWh* | Coupling |
|---|---|---|---|---|---|
| Tesla Powerwall 3 | 13.5 | 11.5 | 97–97.5% | $1,133 | DC or AC |
| StorEn Vanadium Flow* | 30 | 5 | ~75–80% | $500–$900 | DC or AC |
*Based on StorEn’s modular 30 kWh system. The company doesn’t post pricing (or I couldn’t find it), and the prices shown are based on Google and Reddit searches. Prices may vary by region, so click here to get localized pricing.
As you can see, there are pros and cons to both setups. The li-ion batteries are proven tech, but the Gen X-ers and Boomers out there will tell you: 10 years is not a long time, and the thought of replacing your batteries (or, more likely, your inverter) every ten years isn’t a pleasant one.
That said, the vanadium flow batteries I could find seem to “top out” at about 5 kW of continuous output – so if your AC draws more than 5 kW continuously (possible in a large Texas or Arizona home or barnodminium), the system won’t be able to power it.
The final conclusion, then, comes down to what you value as an individual. If you want maximum output to keep the lights on and ride out a power interruption like nothing happened with a decade of reliability baked in, a li-ion setup might work. If you’re primarily interested in keeping the food and medicines in your refrigerator fresh, think replacement is a hassle, and the thought of a one-in-a-million battery fire taking out the 90-point Lancia Aurelia B20 GT that lives in your garage keeps you up at night, the “absolutely will not burn” vanadium flow option might be a no-brainer.
And, don’t forget: while you do need a home backup battery to access solar power during an outage, you do not need a home solar system to take advantage of battery storage.
You don’t need a home solar panel system to reap the benefits of home battery backup. But you’ll get the most out of your system when you pair them together — especially if your utility doesn’t pay you much for the excess electricity your solar panels generate and send to the grid.
That’s a lot to digest, but I hope you let us know which way you’re leaning – or what alternative battery chemistry you prefer – in the comments. And, if you’re looking for some options to giving Elon more money to turn Grok into a far-right propaganda machine, check out these great Powerwall alternatives.
If you’re considering going solar, it’s always a good idea to get quotes from a few installers. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them.
Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisors to help you every step of the way. Get started here.
FTC: We use income earning auto affiliate links. More.
On today’s exciting episode of Quick Charge, we don’t even mention “you know who,” focusing instead on EV news from Rivian, Lucid, Nissan, Ford, and what it takes to make a MAN in the heavy truck space. Check it out!
Sure, Nissan is pushing back production estimates on its yet-to-begin-production Nissan LEAF and Ford’s EV sales were down significantly in Q2, but there’s more to the story than the “Faux News” crowd would have you believe. Plus: some new electric success stories from Porsche and a disappointing (but still cool) dive into some new home backup battery tech.
Source Links
Prefer listening to your podcasts? Audio-only versions of Quick Charge are now available on Apple Podcasts, Spotify, TuneIn, and our RSS feed for Overcast and other podcast players.
New episodes of Quick Charge are recorded, usually, Monday through Thursday (most weeks, anyway). We’ll be posting bonus audio content from time to time as well, so be sure to follow and subscribe so you don’t miss a minute of Electrek’s high-voltage daily news.
Got news? Let us know!
Drop us a line at tips@electrek.co. You can also rate us on Apple Podcasts and Spotify, or recommend us in Overcast to help more people discover the show.
he 30% federal solar tax credit is ending this year. If you’ve ever considered going solar, now’s the time to act. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them.
Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisors to help you every step of the way. Get started here.
FTC: We use income earning auto affiliate links. More.
Battery electric cars sold today in Europe produce 73% less life-cycle greenhouse gas emissions than gas cars, even when factoring in production, according to new research from the International Council on Clean Transportation (ICCT). That’s a big improvement from 2021, when the gap was 59%.
Meanwhile, hybrids and plug-in hybrids haven’t made much progress. The study confirms what clean transportation advocates have been saying for years: If Europe wants to seriously slash emissions from its dirtiest mode of transport – ICE passenger cars, which pump out nearly 75% of the sector’s pollution – it needs to go all-in on battery EVs.
“Battery electric cars in Europe are getting cleaner faster than we expected and outperform all other technologies, including hybrids and plug-in hybrids,” said ICCT researcher Dr. Marta Negri. Credit the continent’s rapid shift to renewables and the higher energy efficiency of EVs.
The makeup of the EU’s power grid is changing fast. By 2025, renewables are expected to generate 56% of Europe’s electricity, up from 38% in 2020. And that’s just the beginning: the share could hit 86% by 2045. Since cars bought today could still be on the road two decades from now, the growing use of clean electricity will only boost EVs’ climate benefits over time.
Gas-powered cars, on the other hand, will stay mostly tied to fossil fuels as the cost and availability of biofuels and e-fuels are still uncertain.
Hybrids and plug-in hybrids only cut lifetime emissions by 20% and 30%, respectively, compared to gas cars. That’s partly because plug-in hybrids tend to run on gas more than expected. So while hybrids aren’t useless, they’re just not good enough if we’re serious about climate goals.
Countering EV myths with hard data
There’s been a lot of noise lately about whether EVs are really that green. The ICCT study takes aim at the bad data and misleading claims floating around, like ignoring how the grid gets cleaner over time or using unrealistic gas mileage figures.
It’s true that manufacturing EVs creates more emissions upfront – about 40% more than making a gas car, mostly due to the battery. But EVs make up for it quickly: that extra emissions load is usually wiped out after about 17,000 km (10,563 miles) of driving, which most drivers hit in a year or two.
“We’ve recently seen auto industry leaders misrepresenting the emissions math on hybrids,” said Dr. Georg Bieker, senior researcher at the ICCT. “But life-cycle analysis is not a choose-your-own-adventure exercise.”
ICCT’s new analysis includes emissions from vehicle and battery production and recycling, fuel and electricity production, and fuel consumption and maintenance. It even adjusts for how the electricity mix will change in the coming years – a key detail when measuring plug-in hybrid performance.
Read more: Volkswagen’s 47% BEV sales jump includes a 24% boost in the US
The 30% federal solar tax credit is ending this year. If you’ve ever considered going solar, now’s the time to act. To make sure you find a trusted, reliable solar installer near you that offers competitive pricing, check out EnergySage, a free service that makes it easy for you to go solar. It has hundreds of pre-vetted solar installers competing for your business, ensuring you get high-quality solutions and save 20-30% compared to going it alone. Plus, it’s free to use, and you won’t get sales calls until you select an installer and share your phone number with them.
Your personalized solar quotes are easy to compare online and you’ll get access to unbiased Energy Advisors to help you every step of the way. Get started here.
FTC: We use income earning auto affiliate links. More.
![Here's our closest look at the Kia EV2 caught testing in the Alps [Video]](https://i0.wp.com/electrek.co/wp-content/uploads/sites/3/2025/07/Kia-EV2-closest-look.jpeg?resize=1200,628&quality=82&strip=all&ssl=1)
The EV2 may be Kia’s smallest electric vehicle, but it has a big presence on the road. Kia promises it won’t feel so small when you’re inside, thanks to clever storage and flexible seating. After a prototype was spotted testing in the Alps, we are getting our closest look at the Kia EV2 so far.
Kia EV2 spotted in the Alps offers our closest look yet
Kia first unveiled the Concept EV2 during its 2025 EV Day event (see our recap of the event) in April, a preview of its upcoming entry-level electric SUV.
Despite its small size, Kia claims it will “redefine urban electric mobility” with new innovative features and more. Kia has yet to say exactly how big it will be, but given it will sit below the EV3, it’s expected to be around 4,000 mm (157″) in length. The EV3 is 4,300 mm (169.3″) in length.
Looking at it from the side, it sits much higher than you’d expect, similar to Kia’s larger EV9. During an exclusive event at Milan Design Week in April, Kia gave a sneak peek of the interior.
Kia said the interior is inspired by a “picnic in the city,” or in other words, a retreat from the busy city life. With a flat-floor design and flexible seating, you can quite literally have a picnic in the city.
Although we’ve seen the EV2 out in public testing a few times, a new video provides the closest look at Kia’s upcoming electric SUV.
The video, courtesy of CarSpyMedia, shows an EV2 prototype testing in the Alps with European license plates. There’s also a “Testfahrt” sticker on the back, which translates to “Test Car” in German.
As the prototype drives by, you can get a good look at it from all angles. Like in past sightings, the front features stacked vertical headlights with Kia’s signature Star Map lighting. Even the rear lights appear to be identical to those of the concept.
The interior will feature Kia’s next-gen ccNC (connected car Navigation Cockpit) infotainment system. The setup includes dual 12.3″ instrument clusters and infotainment screens in a curved panoramic display. Depending on the model, it could also include an added 5.3″ climate control screen.
Last month, a crossover coupe-like model was spotted on a car carrier in Korea, hinting at a new variant. The new model featured a design similar to that of the Genesis GV60.
Kia’s CEO, Ho Sung Song, also recently told Autocar that a smaller, more affordable EV was in the works to sit below the EV2. Song said the new EV, priced under €25,000 ($30,000), was “one area we are studying and developing.”
With the EV4 and EV5 launching this year, followed by the EV2 in 2026, it could be closer toward the end of the decade before we see it hit the market. Next-gen EV6 and EV9 models are also due out around then.
The Kia EV2 is set to launch in Europe and other global regions in 2026. Unfortunately, it’s not expected to make the trip to the US.
FTC: We use income earning auto affiliate links. More.
-
Sports3 years ago‘Storybook stuff’: Inside the night Bryce Harper sent the Phillies to the World Series
-
Sports1 year agoStory injured on diving stop, exits Red Sox game
-
Sports2 years agoGame 1 of WS least-watched in recorded history
-
Sports2 years agoMLB Rank 2023: Ranking baseball’s top 100 players
-
Sports4 years ago
Team Europe easily wins 4th straight Laver Cup
-
Environment2 years agoJapan and South Korea have a lot at stake in a free and open South China Sea
-
Sports2 years agoButton battles heat exhaustion in NASCAR debut
-
Environment2 years agoGame-changing Lectric XPedition launched as affordable electric cargo bike