Rune Raises $40M to Run GPUs on Solar Power That Farms Would Otherwise Waste

San Francisco startup Rune has come out with RELIC, a modular compute unit that plugs straight into operating solar farms and runs GPUs on electricity those farms would otherwise waste. The launch came with a $40 million Series A led by Spark Capital, bringing Rune’s total funding to $53.5 million, DCD reported.

Solar plants can throw away as much as 20% of what they generate, according to Rune, which TechRadar noted adds up to more than 50 TWh a year nationwide. RELIC (Renewable Energy Linked Intelligent Compute) taps that stranded power at the source, skipping the meter, utility fees and the grid interconnection queues that have slowed data center projects.

“Every solar plant is a latent data center. The power is already there, sitting idle while AI labs wait years for grid connections that may never come,” said William Layden, Rune’s co-founder and CEO. “We built RELIC to close that gap with compute that’s online in days, powered by energy the grid was throwing away.”

Weeks instead of years

Rune says a RELIC unit installs in about an hour and can deliver working GPU capacity within six weeks of a contract being signed. It runs natively on direct current, the form solar panels produce, so it avoids the losses of converting to alternating current. The company also says it uses no water and cuts non-compute infrastructure spending by 85%, which it puts at roughly $620 million in savings on a 100-megawatt deployment.

The first working installation sits at a 200-megawatt solar facility in Texas and was mounted on existing infrastructure without modifications. Rune hasn’t named the site.

“Demand for AI infrastructure is growing faster than it can be delivered,” said Santo Politi, founder and general partner of Spark Capital. “Every renewable asset in operation becomes a potential deployment site.”

Rune’s co-founder and CTO, Varun Palivela, framed the problem as one of design. “AI’s power constraint isn’t generation, it’s resource allocation,” he said. “The industry is retrofitting data centers designed for a different era rather than rethinking the architecture itself.”

Some practical questions are still open. Solar output rises and falls with the sun, and Rune hasn’t detailed how RELIC handles that variability for workloads that expect steady power, or published independent data on its efficiency and cost claims. The company, founded in 2023, has so far disclosed only the single Texas deployment.