Sunrun, Voltus turn home batteries into AI data center capacity

Sunrun has signed its second capacity deal with Voltus this summer, this one aimed at the AI data center market. Under the agreement, Sunrun will supply capacity from a portion of its residential storage-plus-solar fleet in PJM and MISO to Voltus's Bring Your Own Capacity program. Data Center Dynamics first reported the deal.

Voltus launched BYOC in October of last year as a workaround for the interconnection queue. Instead of waiting for new transmission and generation, developers assemble a capacity stack from distributed energy resources and offer it to utilities as an alternative route to approval. Voltus says the model can shave years off a buildout and that it has already signed a 100MW agreement with Google on PJM plus a partnership with Octopus Energy US.

The capacity Sunrun is committing comes from its existing residential solar-plus-storage systems, not new construction. Sunrun does not say how many systems or megawatts are involved. The release calls it a portion of a fleet spanning thousands of homes across PJM and MISO. Founded in 2007, Sunrun is the largest US provider of residential solar and battery storage.

The two chief executives frame the logic in similar terms. Sunrun's Mary Powell says meeting growing demand means using every available electron, and notes that hyperscaler money is behind some of those home batteries. Voltus's Dana Guernsey describes BYOC as turning distributed resources into capacity the grid can count on. The marketing language omits one operational point: Voltus says the capacity is market-accredited, meaning wholesale markets recognize it and can settle against it.

This is the second Sunrun-Voltus deal. In June, the two companies and Tesla signed an agreement to aggregate more than 16GW of residential energy capacity across the US for sale to hyperscalers and utilities. That stack would draw on home batteries, smart thermostats, and vehicle-to-grid devices already installed. A 16GW portfolio is a meaningful chunk of generation, but it is spread across homes rather than concentrated in one plant, and its value depends entirely on dispatchability.

The BYOC concept addresses the AI buildout's timeline problem. AI developers want power within a few years; transmission and large generation take far longer to permit, finance, and build. Residential batteries are already commissioned, interconnected, and registered with wholesale markets. They sit in homeowners' garages, yet a hyperscaler can rent their capability through an aggregator like Voltus without owning a single panel. Capacity without construction is the novelty.

For investors underwriting digital infrastructure, this is the distributed fringe of a week otherwise devoted to central stations. Private Infrastructure Daily has tracked Blue Energy and GE Vernova Hitachi advancing a Texas gas-plus-nuclear plant to feed a Crusoe data center by 2030. GDS lifted its sales target past a gigawatt. It also raised capex to $1.4 billion. The Sunrun-Voltus deal builds no turbines and breaks no ground. It finds megawatts that already exist and gives them a schedule. For a hyperscaler facing a years-long interconnection wait, that can be faster than any new plant.

The unresolved question is firmness. A battery fleet is only capacity if it responds when called. Voltus says it has the operational scale. It connects distributed resources to all nine North American wholesale markets. It operates more than 7.5GW. That record suggests the aggregation can work. If it does, the next capacity crunch in the AI buildout may be solved by a price signal. But the release does not say the price, the contract length, or the performance guarantees. Those details will show up in interconnection filings, where utilities will decide whether a stack of home batteries can carry a data center's capacity requirement.