Energy Storage Startups funded by Y Combinator (YC) 2026

Dartboard is an AI Analyst for Electricity Markets, starting with the owners of grid-scale battery projects.

Rewbi uses AI to optimize grid-connected battery storage. We generate revenue by charging when electricity is cheap and discharging when electricity is expensive. We rent battery storage for a fixed fee per month, and we earn 2x that fee in monthly revenue by dispatching the battery optimally. Today, power companies use human traders to manually track grid conditions and update the battery’s dispatch schedule. However batteries can adjust their power output 100x faster than traditional power generation (e.g. hydro, coal, nuclear, gas), with the ability to go from full-speed charging to full speed discharging in under a minute. Electricity prices change every 5 minutes, often by 300% or more. Our AI better tracks 100s of live inputs, and it makes decisions faster than a human operator (with lower overhead!), improving revenue 2x.

Spark AI is workflow software for solar, storage, and data center developers. We've reviewed and identified over 1 million zoning, permitting, and project-related documents in nearly every jurisdiction in America, so that you can instantly identify project requirements, local sentiment, and fatal flaws in seconds. We’re trusted by dozens of industry-leading developers representing over 90 gigawatts of project pipeline and $30 billion in financing. Our team combines leadership experience from AI and energy (Microsoft, Apple, Department of Energy, Brex).

Vista designs, finances, installs, and manages energy storage and solar at commercial, industrial, and multifamily properties for $0 upfront, helping businesses save up to 30% on their energy bills. The founding team previously worked at SpaceX, Rocket Lab, NASA and Firefly.

Founded in 2022, Atmeto was started as a place to develop and apply machine learning to solve the world's biggest problem—climate change. Our current priority is getting the grid to run on 100% clean energy, which is currently limited by battery storage (specifically, the algorithms that control them). We're redefining these algorithms to unlock gigawatts of untapped energy storage capacity, enabling the grid to run on more clean energy from wind and solar.

We are working on rapidly deployable energy storage and power generation solutions for C&I customers, especially in the AI data center space.

We remove CO2 and water from the air and use electricity from solar and wind power to turn them into zero net carbon electrofuels. These are gasoline, diesel, and jet fuels that work in existing cars, trucks and planes without requiring modification of their engines, and don't contribute to global warming because they don't add any new CO2 to the atmosphere. Each gallon of our electrofuels means a gallon of fossil oil left in the ground forever. Importantly, these fuels for the first time can compete with fossil fuels on price - our zero net carbon jet fuel has a price of one cent per gallon less than fossil jet fuel. American Airlines ordered 10 million gallons of this fuel and we will start shipping it next year.

We build engines that have the potential to slash 33% or worldwide CO2 emissions - cost-effectively. First, we help food and mining companies cut both their heat costs *and* CO2 emissions by replacing gas-fired steam boilers with our proprietary high temperature heat pumps. Our heat pumps make up to 3x more heat with the same amount of electricity, even at up to 1000°F. Once the heat pump market is mature, we will address the seasonal energy storage market. Our storage units are based on the exact same proprietary engine we use for our heat pumps. They work with solar and wind, and replace lithium-ion batteries, fossil-fired power plants, CO2 capture and storage, and fuel procurement, with a cheaper, sustainable and more reliable alternative, which can be sited anywhere. The first opportunity is a high-margin market worth 3% of worldwide CO2. The second is a much bigger market worth 30% of worldwide CO2. By the time all cars become electric, it will be even more. Our key is we are building the first Stirling engine to reach 86% of the Carnot efficiency, compared to 64% for the state of the art. We do all that while significantly decreasing costs, and increasing reliability. Please see Airthium's website for more information.

Combining nanotechnology with fundamental chemical engineering principles to accelerate the renewable energy revolution.

Our technology enables li-ion batteries to charge extremely fast while retaining long cycle life using smart control algorithms.

We use machine learning to accurately forecast electricity prices. Our live customers, including Enel, use our software to improve revenue by millions of dollars per year.