Rune, a San Francisco-based company developing modular compute systems, has raised $40 million in Series A funding.

The round was led by Spark Capital, with participation from Union Square Ventures, Lowercarbon Capital, Activate Capital, Committed Capital, Timeless Partners, and Logos Fund. The funding brings Rune’s total raised to $53.5 million.

Rune will use the funding to expand its network of renewable energy partnerships and grow its customer base for AI computing.

The company has launched RELIC (Renewable Energy Linked Intelligent Compute), a modular system that installs directly at solar power sites and uses underutilized solar energy to provide AI compute capacity.

“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, Co-Founder and CEO of Rune. “We built RELIC to close that gap with compute that’s online in days, powered by energy the grid was throwing away.”

RELIC operates off-grid using direct current (DC) power and does not require traditional grid connections, water, transformers, or heavy construction.

“Demand for AI infrastructure is growing faster than it can be delivered. Rune deploys compute directly behind the meter at operating solar farms, converting clean power into rapidly scalable AI capacity,” said Santo Politi, Founder and General Partner of Spark Capital. “Every renewable asset in operation becomes a potential deployment site. Rune is the fastest path to new capacity we have seen.”

“AI’s power constraint isn’t generation, it’s resource allocation,” said Varun Palivela, Co-Founder and CTO of Rune. “The industry is retrofitting data centers designed for a different era rather than rethinking the architecture itself. We built an entirely new technology stack from the ground up, coupling compute directly to clean generation so AI can scale here on Earth.”

Rune says its systems can be installed in about 60 minutes, with compute customers able to receive power in as little as six weeks.

The company currently has live deployments at clean energy sites, including a 200MW solar facility in Texas.