LAS VEGAS — For years, the residential energy storage market was a sleepy place dominated by one big name. Now, more companies are rushing to sell these products than ever before, and some of the new contenders are brands people have actually heard of.

The iconic copper and black Duracell colors now grace a solar-battery product. The perpetually active bunny mascot from Energizer similarly wants to keep your house powered through blackouts with clean energy. Anker, a dominant force in chargers and power packs for personal electronics, has harnessed its engineering and consumer design experience to produce the Solix X-1 solar-battery system, joining a lineup of portable battery packs already on the market. Batteries For Home Solar Power

All this new competition is crucial for turning rooftop solar into a more valuable clean-energy resource. Home solar on its own produces clean energy when the sun shines. Rooftop solar hooked up to batteries empowers households to ride through grid outages unscathed, but it also lets them share clean energy with the grid at hours of peak demand. Networks of home batteries add up to meaningful capacity: They’re already keeping the lights on in Hawaii after a major coal plant retirement and saving Vermonters millions of dollars in grid costs each year.

The Department of Energy wants to supercharge the development of these networks of customer-controlled energy devices, also known as virtual power plants. A “ commercial-liftoff” report published by DOE last week details how supersizing these aggregations can reduce the need for fossil-fueled “ peaker” plants and save money on grid decarbonization by leveraging stuff people are buying for themselves anyway. But for this decentralized vision to succeed, customers need a ready supply of products that they actually want to buy.

Consumer preference is tricky to predict, but the supply, at least, has arrived. In Las Vegas last week at the 40 ,000 -attendee clean-energy trade show RE +, a stroll around the gargantuan two-story expo hall revealed what could be called a Cambrian explosion of residential battery species, if it weren’t imperative to avoid careless references to explosions when discussing lithium-ion batteries.

“ It catches the eye to see how many storage options were being showcased at RE + this year,” said Spencer Fields, director of insights at online solar and storage marketplace EnergySage.

Too many vendors to count are hawking family-sized battery storage products. The vast majority of those new entrants have little to distinguish themselves at this point — they’re anonymous brands selling equally anonymous boxes that do exactly the same thing. Home-storage vendors haven’t learned the lessons of Las Vegas, which entrances even sharp-minded cleantech analysts with its kaleidoscopic colors and sounds.

Nevertheless, these battery packs now enjoy a decade of lucrative tax credits from the Inflation Reduction Act. Seemingly nonstop climate-driven disasters this year have made backup power more visibly valuable than ever before, and new rules in California, the largest home solar and storage market in the country, made batteries essential to selling rooftop solar. Manufacturers from outside the traditional solar industry have noticed.

Tesla didn’t invent battery storage for homes, but Elon Musk popularized the concept when he launched the first Powerwall in 2015 . Tesla then dominated the early years of the fledgling U.S. residential storage market, especially when its second-generation product, unveiled in late 2016 , had increased storage capacity and dropped the price relative to competitors. Tesla promised a built-in inverter at the time but has taken a while to get around to it: The company made headlines last week for promising the exact same thing in the forthcoming Powerwall 3 .

Mercedes-Benz tried to follow Tesla from automotive batteries into home energy, then quickly gave up. Other early adopters kept plugging away, building their home battery brands for American households: German startup sonnen, Tetris-purveyer Henk Rogers’ Blue Planet Energy, South Korean battery juggernaut LG . But an early market where most customers clamored for a single brand left something to be desired: Whenever Tesla fell behind in shipments, which happened regularly as the company prioritized electric-vehicle production, the delays rippled throughout solar-battery installer networks.

For several years now, though, the home storage market has been steadily diversifying.

EnergySage regularly analyzes consumer preferences based on the solar and storage quotes that installers generate on its comparison platform. When its storage marketplace launched in the summer of 2020 , Tesla still led in terms of the number of times its batteries were quoted, followed closely by LG Chem. But at the end of that year, the Korean company recalled some of its home storage systems due to fire concerns, dampening enthusiasm for the product.

Subsequently, leading solar microinverter manufacturer Enphase took market share with its modular battery offering.

Mary Virginia Olano , Julian Spector

As of the first half of this year, Enphase was driving by far the most quotes, followed by Tesla. Another solar inverter leader, SolarEdge, newcomer FranklinWH and high-efficiency solar brand SunPower rounded out the top five. That roster shows the advantages of solar-related equipment companies branching into storage, Fields said: You can buy inverters and batteries from one company, with one warranty and one app. In the case of SunPower, the solar panels are coming from the same place, too.

Even this new, more diversified battery ecosystem has room to grow. Nearly all home batteries get installed via the rooftop solar industry, and Fields noted that the distributed solar industry itself is extremely distributed. The big national players don’t control the majority of the market, and the “ long tail” of small installers adds up to significant market share. That creates opportunities for many storage providers to find a symbiotic partner.

Where Darwinian competition birthed an inconceivable variety of species, home battery competition tends toward similarity.

A few years ago, brands like sonnen and Blue Planet distinguished themselves by evangelizing the more fire-safe lithium ferrous phosphate (LFP ) chemistry; these days, everyone’s into it. Modularity seemed new and exciting when the options for customer sizing were one Powerwall or two Powerwalls, but now stackable Lego-brick batteries are the norm. Indeed, the homogeneity runs more than skin-deep.

“ Most of [these products] use the exact same cells or get their cells from the exact same companies,” Fields pointed out. Chinese manufacturer CATL crushes it in the LFP game, so its battery cells end up in many of the consumer-facing storage products out now. When essentially repackaging the same core product, home storage brands need to find something else to distinguish themselves.

Fields ticked off a few differentiators: inverter power levels, which limit how many appliances a battery can run at the same time; quality of the user-facing app; integration with smart energy management systems like Span or Lumin; ease of installation and commissioning (more a boon to installers, but customers should save on labor costs).

Brand recognition could push certain battery boxes above the fray. I heard several conference attendees independently mention seeing Duracell and Energizer on display; I went searching for them, not for the new brand nobody was talking about.

When so much rooftop solar is sold around the kitchen table, “ What better brand than Duracell to be at the kitchen table?” suggested Aakar Patel, president of Power Center, which licensed the Duracell branding for a line of home storage products.

Likewise, Energizer isn’t making the residential storage packs that bear its name; that’s being handled by a company called 8 Star Energy. The licensed arrangement at least means the home storage system needs to hold up to the quality and performance demanded by Duracell or Energizer to maintain access to the logo. That may count as differentiation in a field where most everyone slaps a label on battery cells made by someone else.

Anker is the one to watch to see if a consumer brand can parlay its hard skills into a more successful home-storage product.

It has thrived as an upstart direct-to-consumer brand and will launch with “ massive lead generation” from its existing, tech-savvy fan base, said Eric Villines, head of global communications at Anker Innovations. But homeowners can’t just buy energy storage online, the way Anker initially sold its chargers and batteries for electronics; that kind of transaction requires help from qualified installers who know how to work with the equipment. Anker now must form alliances with solar installers to deliver Anker batteries to customers.

“ We’re right at the beginning of the conversations with installers and distributors,” Villines said. Las Vegas marked the brand’s first appearance at a U.S. solar industry conference, and “ we’re learning a lot.”

Anker’s permanent home-energy batteries aren’t on the market just yet. They’re in beta-testing in the U.S. now, working toward commercial launch early next year if the company determines everything is ready to go. That would get the product out just in time for what is sure to be the energy storage market’s biggest year yet.

Julian Spector is senior reporter at Canary Media.

Maria Virginia Olano , Julian Spector . 22 September 2023

Jeff St. John . 21 September 2023