In recent years, much has been said about energy storage systems, balancing markets, and the integration of renewable energy sources into the grid. At first glance, everything appears straightforward, but once real work begins, numerous complexities emerge.
Over the past several years, we have integrated both small- and large-scale power plants—solar, wind, and battery storage projects—and worked with various control systems. This experience has clearly shown the challenges involved and what should be anticipated well before project implementation begins.
Connecting Different Power Plants: More Challenges Than Expected
One of the major challenges is connecting several power plants into a single balancing “basket.” At first, this may seem like a simple technical task. However, when you start merging six different plants, the nuances quickly become visible: one system allows control, another does not; one lacks a measurement device, another lacks proper data.
What looked simple on paper ended up taking twice as much time in reality. For example, one project that was planned for two months ultimately took four. Weather conditions also significantly affect the process: if there is not enough sun or wind, systems cannot be qualified, delaying testing.
Slower Processes
This year, we have observed that both operators and project developers still lack experience. Processes that previously took a few days now stretch up to 40 working days.
For instance, mathematical model verification used to take two weeks — now it takes two months. The reason is simple: a massive influx of projects and new requirements introduced during ongoing work. Therefore, if previously we expected to commission a power plant in a couple of months, now we must plan for at least four or five.
Manufacturer “Innovations” That Are Not Yet Working
Another lesson: do not rely solely on features described on paper. Manufacturers often introduce new controllers or inverters with additional functionalities that theoretically should manage storage systems more efficiently. In practice, however, these functions often turn out to be unfinished—requiring extra programming and testing, sometimes for up to six months. It is essential to verify whether a feature is truly necessary and operational rather than relying on a manufacturer’s datasheet.
Storage System Operational Challenges
Another issue we encountered is battery cell imbalance—when individual cells charge and discharge unevenly. At first, everything runs smoothly, but within a month voltage differences appear, reducing overall capacity. The system may indicate that the battery is charging, but once it reaches about 70%, the reading suddenly jumps to 100%. The same occurs during discharge.
Therefore, a cell-balancing function is essential. This system equalizes voltage differences between individual cells and ensures uniform operation. Balancing can be performed automatically or through regular maintenance. Without it, the storage system gradually loses capacity, and its state-of-charge indicators become inaccurate.
Temperature is another critical factor. In one project, a battery system was kept in an unheated warehouse where winter temperatures hovered around 10°C. The system attempted to charge the battery, but the process repeatedly stopped. It became clear that heating is just as important as cooling.
In another project, the opposite occurred. A container with batteries was heated continuously — even when unnecessary. As a result, the client consumed as much electricity over the weekend as they earned during the entire week. Proper control of heating and cooling systems is therefore crucial.
Cybersecurity Is a Must
Another important lesson concerns cybersecurity requirements. Since May of this year, these requirements apply to all new solar, wind, and battery storage projects connected to the grid. For a long time, many treated this as a formality that could be addressed later. However, in September, ESO began requiring cybersecurity reports proving that all systems meet established security standards.
Only then did it become clear that without these reports, power plants simply would not be permitted to operate. Therefore, cybersecurity measures must be included in project planning and budgeting from the very beginning.
These experiences have shown that integrating energy storage systems and renewable energy sources is not just a technological process but a continuous learning journey. Flexibility, collaboration, and the ability to adapt to evolving requirements are essential. Each project becomes both a challenge and a step toward a more mature, efficient energy system.
Dr. Šarūnas Stanaitis, CEO of “Inion Software”