Sunrun Battery Attachment Hits 70% as Home Storage Surges

In the second quarter of 2025, 70% of Sunrun's new customers added a home battery alongside their rooftop solar. A year earlier, that share was 54%.

That's a big shift in how people power their homes. Storage is no longer an add-on. For many households, it's now the default.

Here is what Sunrun reported, what's driving the shift, and why it matters for the grid and for owners of solar in the Northeast.

How Fast Is Sunrun's Battery Business Growing?

Sunrun's battery attachment rate hit 70% in Q2 2025, up from 54% a year earlier, and it installed 392 MWh of storage in the quarter, up 48% year over year, according to Utility Dive. It added nearly 29,000 new customers in the quarter.

The key numbers:

• ●Battery attachment rate. 70%, up from 54%.
• ●Storage installed in Q2. 392 MWh, up 48%.
• ●Solar installed in Q2. 227 MW, up 18%.
• ●Cumulative storage. 3.2 GWh across 195,000 solar-and-storage systems.
• ●Target. 10 GWh by 2029.

Storage is growing much faster than solar alone. That's the real story in the numbers, and it's reshaping what a typical solar installation looks like.

Why Are More Homeowners Adding Batteries?

California's net billing tariff, often called NEM 3.0, cut compensation for exporting midday solar and rewards homeowners who store power and use it during peak hours. California is Sunrun's largest market, so policy there has an outsized effect.

Under the old rules, sending excess solar to the grid at midday earned good credit. Under the new rules, that same power is worth much less, while power used or dispatched in the evening is worth more.

A battery captures that difference. It stores cheap midday solar and uses it when grid power is most expensive. For many homeowners, that makes storage the better economic choice, not just a backup plan.

Storage isn't an upgrade anymore. It's how solar makes the most economic sense.

How Does a Battery Work Alongside Solar?

A battery paired with solar stores excess power produced during the day and releases it later, when the home or business needs it or when grid power is most expensive.

Without a battery, solar power that isn't used right away flows back to the grid. What that exported power is worth depends entirely on local rules.

With a battery, the owner decides when to use it. The typical daily pattern:

• ●Midday. Solar powers the building and charges the battery.
• ●Evening peak. The battery discharges, reducing expensive grid purchases.
• ●Outages. The battery keeps essential circuits running.
• ●Grid events. In VPP programs, the battery can discharge to support the grid.

How Are Home Batteries Helping the Grid?

In July 2025, Sunrun and Tesla batteries delivered 535 MW to California's grid in a single virtual power plant event, according to Utility Dive. That was with only about 35% of Sunrun's batteries enrolled in VPP programs.

A virtual power plant pools many small batteries so the grid can call on them together. When demand spikes, they discharge at once, reducing the need to fire up expensive peaker plants.

Puerto Rico has shown the same model at scale. Its virtual power plant dispatched about 70,000 home batteries during summer 2025 shortfalls. And California's shift to solar and batteries is already cutting its use of natural gas.

Why Does Distributed Storage Matter for the Northeast?

The Northeast faces aging infrastructure, rising electrification, volatile weather, and some of the highest electricity rates in the country, all of which make distributed storage more valuable.

Rate pressure is already intense. Con Edison sought double-digit rate increases to fund grid upgrades in New York City, and regulators approved a smaller three-year increase in early 2026.

Distributed batteries can ease some of that pressure:

• ●Peak reduction. Batteries cut demand during the most expensive hours.
• ●Local reliability. Backup power during outages and storms.
• ●Deferred upgrades. Less need for some costly grid expansions.
• ●Grid services. VPP programs pay participants for making capacity available.

States are building the programs to use them. Michigan is advancing statewide VPP legislation, and New York launched a 1 GW bulk storage program.

Will Regulators Act Before the Next Backlash?

The case for distributed storage is clear, but whether utilities and regulators build programs around it before rate backlash forces the issue is still an open question.

California's rate design pushed storage adoption up quickly. Other states can learn from that, both the benefits and the complaints from customers who saw export credits cut.

The key is designing programs that pay fairly for the value batteries provide, so customers adopt them because it makes sense, not only because the alternative got worse.

What Does This Mean for Commercial Solar Owners?

The same economics driving home batteries apply to commercial solar: storage can shift output into higher-value hours, cut demand charges, and open up grid-service revenue.

Many commercial systems installed in the 2010s were built without storage and are now losing output to aging inverters or degraded panels. Repowering can restore production and, in the right cases, add a battery that changes the system's value.

For more on the process, see what solar repowering involves.

Start With a Ballpark Estimate

Storage is reshaping what solar is worth. Find out what your existing solar project may be worth and whether repowering or adding storage would make it worth more.

Source: Utility Dive, "Sunrun battery attachment rate hits 70%, up 54% from a year ago"