Mixergy Raises £3.6M to Roll Out Smart Hot Water Tanks Across the UK

Mixergy, the Oxford University cleantech spin-out, has raised £3.6 million in Series A financing to support the national rollout of its smart hot water tanks. The round was led by Foresight Williams Technology (FWT), an EIS fund combining the investment track record of Foresight Group with the engineering expertise of Williams Advanced Engineering, which brings significant Formula 1 technical heritage to its portfolio companies. Joining FWT in the round are existing investors Oxford Sciences Innovation, IP Group, and Centrica Innovations — the strategic investment arm of Centrica, which owns British Gas, Mixergy's primary commercial launch partner in the UK.

Mixergy was founded in 2014 by Pete Armstrong and Ren Kang, both of whom developed the core technology during their time in the Energy and Power Group at the University of Oxford. The central insight behind the company is that conventional hot water cylinders heat their entire contents even when only a fraction of the hot water is needed — a deeply inefficient approach that wastes energy and money. Mixergy's patent-pending design uses thermal stratification and precision controls to heat only the volume of water that the household actually requires, delivering water up to five times faster for electric tanks and reducing energy consumption by up to 20 percent.

Beyond household efficiency, Mixergy's platform has achieved a notable regulatory first: its tanks are the first hot water product to be certified to deliver grid balancing services to the National Grid. Through a network of connected tanks — what the company calls the "Internet of Tanks" — Mixergy can turn devices on and off in response to real-time signals about the balance between renewable energy supply and national demand. When excess wind power is available, tanks can absorb it; when demand is high, they can defer heating. This flexibility positions Mixergy at the intersection of home energy management and grid infrastructure, a commercially significant space as the UK integrates more intermittent renewables.

The company has partnered with British Gas to launch the product to households across the UK, giving it access to the country's largest heating services customer base. The relationship with Centrica through the funding round deepens this commercial alignment and creates a pathway to significant volume at the national scale. Mixergy tanks are also compatible with heat pumps and solar PV, making them suitable for the full range of low-carbon heating pathways that UK households are expected to adopt over the coming decade.

The £3.6 million raise will fund the manufacturing scale-up required to support the British Gas rollout, further development of the machine learning software that underpins the platform's personalised heating schedules, and expansion of the company's commercial demand response services to the National Grid.

Sources

• Mixergy — £3.6M Series A announcement
• Tech.eu — Mixergy raises £3.6M (January 2020)
• EU Startups — Mixergy raises €4.2M (January 2020)