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Meet Cactos, a Finnish startup that got €26M to address energy crisis with repurposed Tesla batteries


Finland has cultivated a vibrant tech ecosystem, giving rise to several popular startups that have made waves on the global stage. Among these, Helsinki-based Supercell stands out as a mobile gaming giant, known for creating globally acclaimed titles like Clash of Clans and Clash Royale. Another notable success story is Rovio Entertainment, the creator of the iconic Angry Birds franchise. Beyond gaming, Finnish startups like Wolt have gained recognition in the food delivery sector, providing seamless services across numerous countries. Additionally, Varjo, a Helsinki-based company, has made significant strides in the virtual and mixed-reality space. 

The country has also been actively participating in the global clean energy transition, and several startups are likely to be involved in smart energy solutions, including energy storage. One of them is Cactos–a developer of smart energy storage systems built from second-life Tesla EV batteries–which has raised over €26 million to expand its portfolio as it aspires to transform the country’s energy landscape. The investment was led by OP Finland Infrastructure LP and the Finnish Climate Fund, and forms part of Cactos’ plans to raise €70 million in capital (consisting of €35M in equity and €35M in debt) to invest in its energy storage units.

Energy storage is critical in supporting the transition from carbon-emitting fossil fuels to weather-dependent renewables like wind or solar. TFN asked Cactos founder and CEO Oskari Jaakkola about how Cactos works and the difference they aspire to make.

Supporting the transition to greener energy

Until relatively recently, everyone was reliant on the electricity generated and supplied through their national grid, which could mean fluctuating prices as demand levels change. But advances in battery technology are changing that, and Cactos’ batteries are creating power self-reliance for their users.

“A typical use case would be to charge the unit from the grid during cheaper power prices at night,” Jaakkola explains, “then discharge during the day to offset consumption from the gird during more expensive power prices.” However, he adds, the system is about more than just benefiting from cheaper power.

“Each unit can be used for the benefit of the building where it is installed, for instance in Load Shifting, Peak Shaving or Back up power,” says Jaakkola. And they can help every power user. “All the units together can be used for the benefit of the whole transmission system, or grid, of the country by operating them together as a large virtual battery.”

It means that also while each user can determine their own use for their battery, they also collectively contribute to the efficiency — and carbon reduction — of their national grid. A feature that attracted OP Finland Infrastructure’s Tuomo Ursula, “the growth in weather-dependent electricity generation has also increased the volatility of the electricity markets and the need for energy storage,” he said. “We are happy to be able to work together with Cactos to offer solutions that benefit the customers and simultaneously improve the stability of the entire electricity grid.”

Providing an energy storage backbone

This is all made possible by the Cactos’ software, Cactos Spine. The automated software takes care of all the energy management decisions required to make the best use of the system.

“Cactos Spine receives real-time measurements of power consumed and generated at a given location,” Jaakkola says. “Using electricity pricing information, weather forecasts, local consumption forecasts and other parameters, it calculates the optimal operating profile for the energy storage system.” It means the automated system takes care of everything, from buying lower priced energy and supplying it later to save costs, to selling back surplus energy at peak times. And the software re-calculates every few minutes to ensure that it is always operating to maximise the unit’s profitability.

Founded in 2021, Cactos manufactures and manages its energy storage units and currently has around fifty Cactos One units in operation. The system is already in use with major Finnish enterprises like Logitri Oy, Ahola Group Oy, Heka Oy, and Keskusosuuskunta Oulun Seudun Sähkö. And it is particularly popular with logistics companies who benefit not just from the savings and energy management, but also its value in managing electric vehicle fleets, something that increasingly important in the logistics industry.

Indeed, Cactos’ largest installation to date, a 2.5 MWh system, is in a logistics centre. To indicate how much power that is, a typical family home uses about 130 kWh a week, “a 2.5 MWh system could power it for almost five months,” Jaakkola told us, although he stressed that was just an illustration for us. “These units are not typically for powering a single-family home,” he said, “so it’s a purely theoretical example!”

However, the same of that single system highlights the difference that could be made by Cactos’ plans to scale up to around a 1,000 battery installations.

The most obvious beneficiaries will be Cactos’ clients, says Jaakkola, “more companies will have the opportunity to get a Cactos energy storage system and hedge themselves against electricity price volatility, limit their peak power and participate in the grid services markets to earn revenue.” But, he adds, the collective storage provided will have a much wider impact.“A thousand Cactos One systems will also have real-life stabilising effects on grid frequency and electricity prices in Finland,” Jaakkola told us. Offering a system that supports the growth of renewable energy generation and increasing grid resilience, Jaakkola says, “The fleet of Cactos units will help not only our clients but also all other electricity users in the country.”

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