The home battery stopped being a toy

The home battery became infrastructure in 2025. The United States installed a record 57.6 gigawatt-hours of new energy storage that year, roughly 30% above 2024 by the SEIA and Benchmark count and up 52% by Wood Mackenzie’s, and the residential segment specifically set its own record.1 More telling than the volume is the attach rate: about 45% of new residential solar now ships with a battery, an all-time high, as states replace one-for-one net metering with net-billing structures that make storing your own power worth more than selling it back.2 The battery is no longer the upsell on a solar system. In many markets it is the reason to buy one.

The market has a clear winner, which is the warning

Tesla dominates the hardware. It held roughly 70% of the broader US storage market in early 2026, and the Powerwall carries about a 34% share of residential batteries specifically, with Enphase and LG closing the gap.3 For anyone thinking about where the durable return sits, a single manufacturer holding a third of the residential market is a reason to stay out of the hardware, not to chase it. The cell is becoming a commodity with a dominant brand and deflating price. A residential system now installs at roughly $800 to $1,200 per usable kWh, putting a typical 10 to 13.5 kWh battery at $9,000 to $18,000 before incentives.4 Commodity plus deflation is a bad place to own the margin.

The chemistry will keep changing, which is also a warning

Today’s default cell is lithium iron phosphate: safe, long-lived, and cheap enough to have won. The interesting challenger is sodium-ion, largely because of cold performance, where CATL’s first-generation sodium cells hold over 90% of capacity at -20°C and HiNa reports 85% at -30°C, which matters in a Colorado garage in January.5 It is not ready: you cannot yet buy a UL 9540-listed residential sodium system with a warranty near the 10 to 15 years LFP offers, and the 2025 collapse of sodium pioneer Natron shows that a promising chemistry can still fail commercially before it matures.5 If you are buying a battery this year, buy LFP. But the point for an investor is the opposite of a chemistry pick: the cell inside the box is going to keep changing, and any capital tied to a specific chemistry ages badly.

The money that does not deflate is the service layer

Every one of those batteries has to be sized, permitted, installed, inspected, warrantied, serviced years later, and enrolled in the utility program. That work is local, fragmented, reputation-driven, and indifferent to which cell is inside the box. It also carries better and more durable economics than the hardware. Solar-and-storage installers run 25% to 35% gross and 5% to 15% net margins, with battery attach adding a 20% to 30% gross margin on the unit and labor plus recurring monitoring revenue; installation labor alone runs $2,000 to $3,500 on a straightforward job.6 The pressure in that model is customer acquisition, which Wood Mackenzie clocked rising 40% year over year to $0.84 per watt, so the installers that win own their lead flow rather than buying it.7

Then there is the new revenue line that did not exist a few years ago. Utilities now pay homeowners to enroll a battery in a virtual power plant and discharge it at peak, worth $50 to $100 a month in several states, or $500 to $1,500 a year, enough to cut two to three years off the payback period; the installer configures and submits that enrollment.8

Where I land

I have no idea which cell chemistry wins in ten years, and neither does anyone selling one. That uncertainty is the entire reason to avoid the hardware and buy the layer above it.

Demand is compounding, the product is becoming standard infrastructure on a solar roof, and the technology is confusing enough to keep patient money out of the operating business while it chases the cell. The installer sizes the system, pulls the permit, carries the warranty, services it in year seven, and now enrolls it in a program that pays the homeowner every month. That is recurring, local, reputation-gated work, and it earns the same margin whether the box behind it holds lithium or something else entirely. I would rather own that business than the one that invented the cell chemistry inside the box. The one risk I would underwrite carefully is policy: net-billing rules and VPP payments are set by regulators and utilities, and a rule change can move the payback overnight. But the work of putting the box on the wall and keeping it running is demand that compounds regardless.