Iryna Beresnieva, Tolk: «Our Task is to Make Cooperation with the 'Sun' Precise and Controllable»

Excess electricity during the day and shortages in the evening — this is the reality of Ukraine’s energy system today, which is oversaturated with solar generation. What began as a “green” revolution has turned into a serious technical problem that threatens the stability of the grid. How can this chaos be balanced and the uncontrollable sun be turned into a predictable resource? Iryna Beresnieva, CEO of the energy supply company Tolk Ukraine, shares her vision in an interview with Energy Business magazine.

How do you assess the current state of solar generation in Ukraine today?

The situation is complex and, at the same time, telling. What we see today is not just a technical problem, but also the result of years of ignoring a systemic approach. In the early 2010s, solar generation in Ukraine began to develop against the backdrop of very generous “green” tariffs. This led to a real boom, but without proper integration into the energy system, without balancing capacities, and without energy storage systems. We built up solar generation, but we did not create the mechanisms for its safe use.

Today, during daytime hours, the curtailment of solar generation reaches up to 2 GW.

Traditionally, balancing in the Ukrainian energy system was handled by hydro and thermal power plants. But even back then, they could not respond effectively to the rapid changes in generation from renewable energy sources. And now, during the war, many of them have unfortunately been destroyed.

However, the balancing system must work precisely; every kilowatt must be manageable. And solar generation, as we know, has peak productivity during the day, which hardly ever coincides with peak consumption.

Globally, we are now observing a situation where there is sun, but no consumption. Or when there is demand, there is no sun. This is a challenge not only for the United Power System of Ukraine or the European energy system but for every one of us who is responsible for a reliable electricity supply and responsible consumption.

What is the biggest threat to the energy system from solar power plants?

It all starts with physics—the sun doesn’t generate electricity “on demand.” Wind, clouds, dust, the time of year—everything has an impact. As a result, we have “windows of surplus generation” in the afternoon and “deficit gaps” in the evening when people turn on their lights, cook dinner, and start up energy-intensive appliances. This creates significant risks for the grid balance.

Plus, there is uncontrolled construction. In some regions, solar power plants were built chaotically: without considering the grid’s capacity, without power limiters. Furthermore, consumers are actively switching to daytime self-sufficiency, and we are seeing a change in the load profile on the energy system, which can no longer be forecasted using conventional methods.

But there are solutions, right? Storage systems?

Exactly. And I have unwavering faith in new technologies that help overcome chaos. At our company, “Tolk Ukraine,” we are preparing to launch the first stage of an energy storage facility in 2025 — with 17 MW of power and a capacity of 50 MWh. This will be a real step towards strengthening the stability of the energy system.

We will be able to accumulate the daytime surplus of solar energy and supply it in the evening when there is increased demand.

This is not just an investment in equipment—it’s an investment in the trust of our clients and in unwavering stability. In reality, when there’s a war outside and it’s dark at home, you don’t think about megawatts. You think differently: why is there no light and why is the power fading? And this is precisely where we are ready to offer a solution.

Your company is not an electricity producer, yet you are actively involved in the “green” energy sector. Why is that?

Because we don’t just sell electricity; we build and maintain a system of trust. Within the Tolk Group of Companies, we work with both households and businesses: from connecting “home” solar power plants to designing integrated solutions for enterprises with storage, consumption optimization, night tariffs, and charging infrastructure for electric vehicles. People want to control their consumption, and businesses want to control their costs. Tolk is always there to help with that.

What will happen if the problem of balancing renewables is not solved?

It will lead to a rapid halt in the development of “green” energy in Ukraine and worldwide. Already, as I mentioned earlier, the transmission system operator is forced to curtail solar power plants during certain hours. This is a bad signal for investors, and it’s a path that undermines all the efforts made. To develop the green sector, we must provide it with a stable infrastructure—technical, regulatory, and financial. Otherwise, we risk turning solar generation from a pillar of support into a threat to energy security.

Despite everything, do you remain an optimist?

Yes. I sincerely believe in Ukrainian energy. And in the people who hold it in their hands every day—from the engineer at the regional power grid to the dispatcher at “Ukrenergo.” We are a nation that strives for improvement for the sake of a happy life, adaptation, and lightning-fast solutions. The sun is our strong partner. And our task is to find solutions that will turn this cooperation into a precise, manageable, and mutually beneficial one.

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