Cactos: repurposing batteries for a greener future

“A Cactus is nature’s battery … It stores water when it’s available and releases it for use later” – Oskari Jaakkola, Co-Founder and CEO of Cactos Oy. 

Oskari has a background in engineering. He is a marine engineer by education and a CFA (Chartered Financial Analyst) charterholder and, before co-founding Cactos, he was focused on business development and structured finance for large energy projects. 

The idea 

It was Oskari’s involvement with wind park transactions that first spurred the idea for Cactos, a Finnish company that build, own and operate an aggregated smart battery energy storage system. 

“In my previous career I was also involved with wind park transactions and the sheer volume of transactions made me think about the temporal imbalance in production and consumption of electricity that they would induce.” 

Between Oskari and fellow Co-Founder Veli-Erkki the idea of an aggregated battery energy storage system was quickly realised. Veli-Erkki already had a company that was repurposing batteries for boats and cars. This led the duo to reach out to their network, more precisely to people with whom they could utilise their specific skillset to make the idea a reality, and so in December 2021, with seven co-founders, Cactos was born. 

What we do 

Cactos build, own and operate an aggregated smart battery energy storage system using recycled electric vehicle batteries. They then lease the individual units to their clients for a monthly fee. This system allows clients to enjoy the benefits of load shifting, peak shaving and reserve power. The units are operated by a Cactos proprietary cloud computing service which utilises artificial intelligence to allocate each unit the optimal service mode. This is tailored to the individual unit and based on grid level and local inputs. 

The units are located at client premises and offer high-capacity back-up power and perform energy optimisation operations, making it economically beneficial. 

“The Cactos One system consists of the Cactos One energy storage unit (ESU) and the Cactos Spine cloud computing system. Each ESU holds 100kWh of capacity and provides 50kW charging and discharging power. Multiple units can be installed to achieve larger systems. 

Cactos Spine calculates the optimal running schedule for each ESU based on local parameters such as purchase price of electricity, sales price of electricity, connection size, peak power-based charge and so on. The target of the schedule is to maximise the profit of the system. The ESU embedded system then executes the schedule. 

The schedule includes load shifting (charging when power is cheap and discharging when it is expensive), peak shaving (limiting peak current, power or both) and demand response (e.g., FCR (Frequency Containment Reserve), and aFRR (automatic Frequency Restoration Reserve)).” 

How it helps 

The units participate in the TSO’s (transmission systems operator) demand response markets, and clients can choose if they wish to be a part of that (to share the revenue). The system is available to clients 24hrs a day, seven days a week for the duration of their contract. The client need not do anything. 

One of the big draws for the Cactos One is the savings clients receive on their energy bills “Some of our clients routinely receive negative electricity bills – they receive money.” 

Oskari believes that this makes Cactos unique as “there are not so many companies who offer the energy storage unit, the control and optimisation software, installation, operation, 24/7 monitoring, financing, maintenance and recycling in one package at a monthly fee. I believe that sets us apart.” 

Another positive aspect is the system can replace expensive reserve power systems like UPS’s or diesel gensets. 

“Our system also provides frequency response services to the transmission grid and therefore helps the whole system maintain balance of supply and demand, enabling the introduction of more renewable power in the system.” 

The ups and downs 

The biggest challenge Cactos has faced is that the concept of energy storage is a new one for a lot of people and so, to attract investment, they have needed to teach investors what the system is, and why it helps. The other challenge has been to then educate clients, suppliers and regulatory bodies about what the system is and how is helps. This is something that Oskari assures is not difficult because the concept is straightforward. However, what makes it a challenge is that it is a time-consuming process. 

What is obvious is that the time they have put in has paid off, and despite the revolutionary concept they have secured investors and clients, and are now gaining traction – with this year seeing their team expand. 

Oskari enthuses that a highlight for the team was when they hooked up their first unit at a client’s factory. “In a rapidly expanding startup, that was one of the best moments.” 


The batteries have a ten-year guarantee. After this period passes, the team reassess their condition. If they find they still have life left in them, they will continue to use them. Any batteries that have used up all their useful life are recycled via a specialised company with whom Cactos has a contract with. 

What’s next 

As the popularity of energy storage is growing, so too must Cactos, and January will see the team expand as they welcome new members. 

Their next adventure? To install over one hundred units in a year. No small task. But with both the energy and battery economy due a much-needed overhaul, and with the talent and determination of the Cactos team, anything is achievable. 

It is only the beginning of the journey for this innovative startup. Who knows to what heights they will take their system in the future – it will certainly be interesting to find out.