08.09.2026
On 8 September 2026, Energy Club held a closed online meeting for representatives of its member companies and invited experts, focusing on European experience in the development and deployment of battery energy storage systems.
The keynote speaker was Oskari Jaakkola, CEO of the Finnish company Cactos, which specialises in the development, manufacturing, financing, installation and operation of intelligent BESS solutions. The discussion was moderated by Valerii Bezus, Vice President of Energy Club.
Participants examined practical models for deploying energy storage systems in the commercial and industrial sectors, integrating BESS into the power grid, managing imbalances, providing backup power, enabling local flexibility and improving power quality. They also discussed the prospects for developing new services for distribution system operators.
Particular attention was given to Cactos’ practical experience in Ukraine and to the European approaches that could help strengthen the resilience of Ukrainian businesses and the country’s energy system.
At the beginning of his presentation, Oskari Jaakkola introduced the structure of Cactos’ business. Founded in 2021, the company has manufactured and installed more than 150 MWh of battery capacity, comprising over 450 individual BESS units.
The largest Cactos system currently in operation has a capacity of 14.2 MWh. The company’s current order backlog amounts to approximately 220 MWh across seven countries. In addition to Finland, Cactos operates in Sweden, Norway, Denmark, Estonia, the Netherlands and Ukraine.
Approximately 60% of the company’s revenue comes from behind-the-meter solutions for commercial and industrial customers, while around 40% is generated by front-of-the-meter, grid-scale energy storage projects.
A defining feature of Cactos is its vertically integrated business model. The company designs and manufactures its own BESS equipment at its factory in Kempele, Finland, and manages installation, commissioning, technical maintenance and system operation.
Cactos can also finance projects, optimise the operation of storage assets, trade electricity and provide electricity supply services. Its software, battery management systems, embedded control systems and trading dispatch interfaces are all developed in-house.
According to Oskari Jaakkola, one of the main drivers behind the rapid deployment of BESS across Europe is the accelerating electrification of industry, transport, utilities and data centres.
This transition is increasing not only overall electricity consumption but, more importantly, the peak capacity required by individual businesses and new facilities. Electricity grids are not always able to expand at the same pace.
While new generation can often be developed through relatively local projects, expanding transmission and distribution infrastructure requires significant investment, complex permitting and long implementation periods. In some European countries, businesses may have to wait for years to obtain a new grid connection or increase the capacity of an existing one.
Jaakkola highlighted the Netherlands as an example of a market where grid congestion has become particularly severe. In one customer case, a food-processing company wanted to launch a second production line, but the grid operator informed it that obtaining the required additional connection capacity could take more than ten years. The alternative was to combine local solar generation with a battery energy storage system.
The decentralisation of the power system is therefore becoming more than a policy choice. It is increasingly a practical consequence of business demand growing faster than the capacity of centralised grid infrastructure.
Oskari Jaakkola emphasised that battery energy storage systems are often associated primarily with ancillary services and frequency regulation. However, for commercial and industrial customers, participation in these markets is only one of the potential functions of BESS.
In practice, a battery can simultaneously provide:
As electricity markets mature, the importance of individual revenue streams may change. The economics of a BESS project should therefore not depend solely on one source of income, such as the ancillary services market.
A more sustainable model is one in which the storage system addresses a genuine local need while simultaneously participating in several electricity markets.
One of the practical examples presented during the meeting was a project developed for Wibax, a logistics company that is electrifying its transport fleet.
At the company’s terminal in Malmö, electric trucks need to be charged at approximately 400–500 kW. However, the site’s existing grid connection can supply only around 138 kW, and the local distribution system operator was unable to increase the connection capacity within the required timeframe.
The problem was addressed by installing a BESS. During truck charging, the battery provides approximately 300 kW of additional power, allowing the total charging capacity to exceed 400 kW while keeping the power drawn from the grid within the permitted limit of approximately 138 kW.
Once the truck charging session is complete, the battery gradually recharges from the grid. In effect, the BESS distributes electricity consumption over a longer period and enables the customer to use the existing grid connection much more efficiently.
The case demonstrates how a battery can provide a practical alternative to waiting several years for grid reinforcement, allowing businesses to proceed with investment projects despite limited grid connection capacity.
Another important area of Cactos’ work is imbalance management across a distributed customer portfolio.
Local generation, charging stations, industrial machinery and other large loads with irregular operating patterns make demand forecasting increasingly difficult. For an electricity supplier or balance responsible party, this creates the risk of substantial imbalance costs.
A combination of BESS and real-time metering makes it possible to adjust the portfolio position during the settlement period itself. If actual consumption exceeds the volume of electricity purchased, the battery discharges. If the portfolio is long, the battery charges.
According to Oskari Jaakkola, Cactos uses this mechanism in its own operations as an electricity supplier. Through forecasting, real-time data and automated control of distributed batteries, the company can almost entirely eliminate imbalances within its portfolio.
Reducing imbalance risk is important not only for the operational stability of an electricity supplier. It also means that the expected cost of this risk does not have to be fully transferred into the electricity price paid by customers.
A substantial part of the meeting focused on the operation of BESS under the conditions of damaged energy infrastructure and prolonged electricity outages in Ukraine.
Oskari Jaakkola presented data from a Cactos-equipped facility in Poltava. During the first months of the year, the system detected 380 power interruptions. In February alone, 209 outages were recorded, while the total duration of unavailable grid supply exceeded half of the entire month.
During every interruption, the BESS automatically isolated the facility from the external grid and continued supplying its internal load. When grid power returned, the battery recharged in preparation for the next potential outage.
Despite this extremely demanding operating pattern, there was no occasion during the winter when the battery at this facility was fully depleted. The facility’s electricity consumption continued without interruption.
According to Jaakkola, batteries offer significant advantages as a source of backup power. They respond almost instantly, require less maintenance and do not depend on fuel deliveries. For longer periods of autonomous operation, BESS can be combined with solar generation, gas generators or diesel generators.
A battery can also reduce the number of generator starts, optimise its operating regime and lower the risk of mechanical failure.
Valerii Bezus noted that, for Ukraine, the deployment of BESS has not only an economic and technological dimension but also a critical security component. In the context of Russia’s deliberate attacks on energy infrastructure, storage systems are becoming a practical instrument for maintaining the operation of critical, industrial and commercial facilities.
A separate part of the presentation addressed power quality.
The inverters used in modern BESS installations can rapidly adjust the power factor, compensate for reactive power and help mitigate voltage fluctuations. This is particularly important for facilities with sensitive equipment, including refrigeration systems, production lines and electrical machinery.
The Ukrainian experience has also demonstrated cases of significant frequency deviations after electricity supply was restored. Such readings may indicate that part of the grid was temporarily operating as a local island without synchronisation with the wider European system.
Under these conditions, a battery storage system can disconnect a facility from an unstable grid, form a local microgrid and reconnect only after power quality indicators return to an acceptable range.
The efficient operation of BESS requires continuous optimisation across different electricity markets and the customer’s local needs.
Oskari Jaakkola identified several potential applications for a distributed battery fleet:
In many European countries, the focus is gradually moving away from payments based solely on the availability of capacity and towards deeper participation by BESS in energy and wholesale markets.
At the same time, Jaakkola warned that operating a battery exclusively to maximise revenue from reserve markets does not always create a positive effect for the local grid. A BESS can switch very rapidly from full charging to full discharging. Under certain conditions, this may increase local power fluctuations.
Battery operation should therefore take into account not only trading revenue but also grid conditions, the customer’s needs and the wider impact on the electricity system.
Storage systems installed at industrial and commercial facilities are already being used to manage local constraints, including through peak shaving. However, the same capacity could also provide services to a distribution system operator.
When congestion occurs in a particular part of the network, the DSO could compensate a company for temporarily reducing consumption or changing the operating mode of its battery. This could postpone expensive investment in a new transformer or other grid infrastructure while creating additional capacity for new connections.
According to Oskari Jaakkola, this requires clear price signals and remuneration mechanisms for local flexibility. Bilateral contracts between distribution system operators and BESS owners could be one possible solution.
Such agreements may provide more predictable and durable availability of flexibility resources than a multilateral marketplace, particularly during the initial stage of market development.
One of the most important strategic issues discussed during the meeting was the control of distributed energy resources.
Batteries, solar power plants, inverters, transformers and other equipment are increasingly connected to manufacturers’ cloud platforms. Equipment suppliers can remotely monitor the systems, change their settings and, in certain cases, directly influence their operation.
Oskari Jaakkola drew attention to the absence of sufficiently harmonised rules clearly defining who may access and control such systems. When a significant share of balancing resources is provided by distributed batteries, control over digital platforms becomes an energy security and cybersecurity issue.
For Ukraine, which continues to resist military aggression, the origin of software, the architecture of remote access, the location of servers and the manufacturer’s authority to control equipment remotely should all be treated as important criteria when selecting BESS solutions.
During the discussion, Valerii Bezus asked about typical BESS project implementation timelines and the business models used by Cactos.
According to Oskari Jaakkola, the typical period from order to commissioning for a behind-the-meter system installed at an existing commercial or industrial facility is between two and four months.
For medium-voltage grid-scale projects with a connection capacity of approximately 1–10 MW, the typical delivery and implementation period is around six months. When permitting is included, the full process in the Nordic countries may take approximately nine months.
Cactos offers several cooperation models:
Under its management agreements, Cactos trades on behalf of the customer, while the battery owner receives approximately 92–93% of the trading revenue. A small portion is retained by Cactos as a fee for optimisation and trading services.
For projects in Ukraine, Cactos is prepared to consider direct supply, export credit financing and opportunities to access Finnish support programmes. However, the availability of grants and government support mechanisms cannot always be guaranteed, meaning that the financing structure must be developed separately for each project.
Cactos organises technical maintenance in Ukraine in cooperation with local partners. Its systems are monitored remotely around the clock, allowing potential problems to be identified and addressed before they become noticeable to the customer.
The meeting concluded that battery energy storage should not be viewed merely as a separate category of equipment, but as a multifunctional energy asset.
A BESS can simultaneously:
For Ukraine to move from individual BESS projects towards industrial-scale deployment, it will need to develop not only the technical infrastructure but also local flexibility mechanisms, bilateral agreements with distribution system operators, access for energy storage systems to different market segments, transparent price signals, and robust digital and cybersecurity requirements.
Energy Club will continue its series of professional meetings focused on European experience in energy storage, practical BESS project models and opportunities for cooperation between international technology providers and Ukrainian businesses, EPC contractors, project developers and energy companies.
Cactos has been a member of Energy Club since 2025.
