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.
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Hyundai is keeping the savings going after extending its EV deals yet again. With leases starting as low as $179 a month, the Hyundai IONIQ 5 is hard to pass up right now.
Hyundai extends IONIQ 5, IONIQ 9 lease deals
After a “breakout” month for IONIQ 5 sales in August, Hyundai looks to keep the momentum rolling. At least for another month.
The Hyundai IONIQ 5 remains a top-selling EV in the US, and might be your best bet if you’re looking to go electric.
Through its Hyundai Getaway sales event, the 2025 IONIQ 5 was listed for lease for as low as $179 per month in August. Although the deals were set to end on September 2, Hyundai has extended them until the end of the month.
The 2025 IONIQ 5, now with more range, an NACS port, and a stylish new design, can still be leased for just $179 per month.
That’s for the Standard Range SE trim with a driving range of 245 miles. The extended range IONIQ 5 SE, with up to 318 miles of range, is available from $199 per month.
You can even snag the souped-up XRT trim for under $300 a month right now. All the offers are for a 24-month lease with $3,999 due at signing.
The deals include the $7,500 EV Lease Bonus, which is also set to expire at the end of September. With the bonus, the net cap cost drops to just $24,380 (SE Standard Range RWD model).
| 2025 Hyundai IONIQ 5 Trim | EV Powertrain | Driving Range (miles) | Starting Price* | Monthly lease price September 2025 |
| IONIQ 5 SE RWD Standard Range | 168-horsepower rear motor | 245 | $42,500 | $179 |
| IONIQ 5 SE RWD | 225-horsepower rear motor | 318 | $46,550 | $199 |
| IONIQ 5 SEL RWD | 225-horsepower rear motor | 318 | $49,500 | $209 |
| IONIQ 5 Limited RWD | 225-horsepower rear motor | 318 | $54,200 | $309 |
| IONIQ 5 SE Dual Motor AWD | 320-horsepower dual motor | 290 | $50,050 | $249 |
| IONIQ 5 SEL Dual Motor AWD | 320-horsepower dual motor | 290 | $53,000 | $259 |
| IONIQ 5 XRT Dual Motor AWD | 320 horsepower dual motor | 259 | $55,400 | $359 |
| IONIQ 5 Limited Dual Motor AWD | 320-horsepower dual motor | 269 | $58,100 | $299 |
Hyundai also extended the offers for its new three-row electric SUV, the IONIQ 9. Leases for the 2026 Hyundai IONIQ 9 start at $419 per month. If you choose to finance it, Hyundai is offering a $5,000 cash bonus on all trims.
Both the 2025 IONIQ 5 and 2026 IONIQ 9 are built at Hyundai’s EV plant in Georgia, enabling them to qualify for the $7,500 federal tax credit. With the credit set to expire at the end of September, the savings will likely disappear. It will be up to the automakers to step in with significant incentives to keep lease prices as low as they are.
Want to lock in the deals before they are gone? Check the links below to find local offers on the 2025 Hyundai IONIQ 5 and 2026 IONIQ 9 in your area.
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Costco members looking for a break on car prices can tap into a new Volvo deal this fall. Members can tap into limited-time manufacturer incentives through the Costco Auto Program, a year-round auto-buying service that secures prearranged low pricing. The latest: a Certified by Volvo Limited-Time Special launched this week.
Certified by Volvo vehicles are pre-owned Volvos that must pass a rigorous test with 170+ points, have less than 80,000 miles, and receive a detailed CARFAX Vehicle History Report. They come with roadside assistance, and EVs and plug-in hybrids also include an 8-year/100,000-mile battery warranty.
Until October 31, 2025, eligible Costco members can score an exclusive bonus when buying select Certified by Volvo vehicles from model years 2022 through 2025.5. Gold Star and Business Members get $1,000 off, and Executive Members get $1,250 off. The offer applies to hybrids, plug-in hybrids, and BEVs. What makes this deal sweet is that the Costco perk stacks with any other manufacturer incentives you qualify for.
Among the vehicles on the eligible list: The Volvo EX30, the EX90, the XC90*, the most requested premium midsize SUV among Costco members last year, and the Volvo C40 EV, which also topped requests in the premium electric compact SUV category.
To cash in on the offer, Costco members must register online for a certificate, then bring it to a Volvo dealership where they present it at the time of purchase. Full details are on the Certified by Volvo Limited-Time Special page.
*CarsDirect links are trusted affiliate links
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.
The GV90 is set to arrive as the most luxurious Genesis vehicle to date. With its debut approaching, Genesis is showcasing the ultra-luxe SUV at its new flagship brand space.
Genesis opens new brand space based on the GV90
Although it’s not yet in production form, Genesis is still showcasing its stunning new full-size electric SUV. The Neolun concept, unveiled last March at the New York Auto Show, will soon arrive as the brand’s new flagship model.
When Genesis launches the GV90, expected in mid-2026, it will become the brand’s largest and most luxurious electric vehicle yet.
According to Genesis, the GV90 is “an ultra-luxe, state-of-the-art SUV” that will take the luxury brand to the next level. We’ve seen camouflaged prototypes out testing a few times, revealing advanced new features and luxury design elements, such as coach doors, adaptive air suspension, and more.
The GV90, or Neolun concept (for now, at least), is the centerpiece of the company’s new “Night in Motion” space, which Genesis opened on Thursday.
Based on the Neolun concept, the new exhibition is “the starting point of the Genesis brand’s spatial philosophy.” It’s designed to showcase the brand’s latest design and the beauty of Korean aesthetics.
Genesis is expected to launch the GV90 in mid-2026, but we could see an official debut before the end of the year.
We will learn prices, range, and other specs soon, but the GV90 is expected to debut on Hyundai’s new eM platform. Hyundai claimed the new platform will “provide 50% improvement in driving range” compared to current EVs. It will also offer advanced Level 3 autonomous driving features.
One thing is sure: The Genesis GV90 won’t be cheap. As its largest and most luxurious SUV, the GV90 is expected to start at around $100,000. Higher trim levels could reach upwards of $120,000 or more.
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