Battwoo Cuts Solar Storage Costs by 30% Using EV Batteries

French startup Battwoo is converting electric vehicle batteries that have retired from cars into stationary storage units for solar energy. The company aims to extend the useful life of these batteries from roughly 15 years to 30, preventing them from going directly to recycling while offering a cheaper alternative to new lithium-ion cells.

The core of the business model rests on the fact that many EV batteries still hold 70% to 80% of their original capacity when they are no longer suitable for vehicles. Battwoo sources these modules, tests them rigorously, and refurbishes them at a workshop in Madrid. This approach addresses a growing challenge in the photovoltaic sector: how to store solar electricity generated during the day for use when the sun is not shining.

Rigorous Testing Ensures Safety

Not every used battery is suitable for this second life. Battwoo only accepts modules that retain more than 80% of their capacity after undergoing diagnostics in-house and by an accredited laboratory. This strict filtering process is designed to maintain high standards of safety and performance, ensuring that the refurbished systems are reliable for long-term use.

The company emphasizes full traceability throughout the process, overseeing every stage of requalification. By controlling the supply chain from sourcing to final assembly, Battwoo seeks to mitigate the risks associated with second-hand components. This industrial capability allows them to guarantee that the batteries meet specific safety requirements before they are installed at customer sites.

Early Projects Show Practical Use

Battwoo has already installed its systems in a few early projects in France. One example is a padel club in the Hauts-de-France region, which uses a 350 kWh storage system to power its illuminated courts in the evening. The system stores surplus solar power generated during the day, effectively shifting the energy usage to when it is needed most.

Another client, an apple producer, uses similar technology to stabilize electricity supply for cold-storage facilities and sorting lines. These real-world applications help the company test its model on an industrial scale. Battwoo is currently focusing on projects below 500 kWh to ensure reliability, with plans to scale up to systems of 1 MWh and eventually several megawatts as it gains confidence in the technology.

Lower Costs and Carbon Footprint

The primary financial benefit for customers is a significant reduction in cost. According to the company, a refurbished 500 kWh battery system costs approximately 30% less than an equivalent new system. This price difference makes stationary storage more accessible for industrial sites and photovoltaic operators who might otherwise find the upfront investment prohibitive, according to reports from pv-magazine.com.

There is also an environmental trade-off to consider. While reusing batteries reduces the need for new raw material extraction, it requires careful management to ensure safety. Battwoo estimates that extending the service life of batteries by decades can reduce the associated carbon footprint to one-quarter of that of a newly manufactured unit. However, the success of this model depends on the continued availability of suitable used EV batteries and the ability to maintain rigorous safety standards at a larger scale.