Optimizing RES in an Unbalanced Energy System: A Perspective from Yehor Zakharchenko

02.10.2025

On September 25, the Energy Club forum “Resilience and Transformation: Balancing Ukraine’s Energy System in a New Reality” was held in Kyiv. Yehor Zakharchenko, Head of the RES and Battery Energy Storage System Projects Department at D.TRADING, during his speech, revealed the key challenges and opportunities for optimizing renewable generation in an unbalanced energy system. He focused on the causes of these challenges, their costs, and ways to minimize losses.

A Drop in Consumption and a Growing Share of RES

According to Yehor Zakharchenko, after the full-scale invasion began, electricity consumption in Ukraine sharply decreased: from 144 million MWh per year, the country moved to 98 million MWh for two consecutive years. At the same time, the share of RES has grown by 3% and now stands at 11% of the energy system’s balance.

“It might seem that 3% is not much, but on the scale of the energy system’s balance, it is very noticeable: both for electricity prices and for dispatching,” he emphasized.

Of the 11 million MWh of RES generation in 2025, 75% comes from solar energy. However, a key element – battery energy storage systems (BESS) – is still lacking. For comparison, in the UK, batteries already account for about 10% of the total installed generation capacity in the country.

In Ukraine, according to Yehor Zakharchenko, if the planned projects for 2 GWh of BESS capacity are implemented, this technology could approach 7% of the total power balance.

Distributed Generation as a Trend

The speaker called distributed generation “the only window of entry” for investors into the Ukrainian energy sector. Unlike wind, which requires large investments and expertise, solar power plants (SPPs) remain an accessible option for large companies as well as for small and medium-sized businesses.

“In my opinion, this trend will continue. An 11% share in the balance is not the end, but only the beginning,” stressed Yehor Zakharchenko.

Two Key Challenges for RES

1. The cost of electricity and imbalances.
   • The price of “solar” generation falls every year as volumes increase. The only exception was 2022, when regulatory restrictions kept the price no lower than 2,646.25 UAH/MWh.
   • The average losses due to imbalances for an SPP operating independently on the market in 2025 are: 0.40 UAH/kWh when the forecast is higher than the actual output, and 1 UAH/kWh when generation exceeds the forecast.
2. Operational constraints and the war factor. In the East of the country, due to destroyed infrastructure, distribution system operators are forced to curtail generation instantly. This creates unpredictable imbalances that are impossible to forecast.

“These challenges complicate the work for both investors and Ukrenergo dispatchers,” the speaker noted.

Solutions: From ESS to Aggregators

Yehor Zakharchenko highlighted several tools:

• Energy Storage Systems (ESS)—they increase the value of solar generation by 80%, based on the 2025 operating model.
• Quality Forecasting—Using several models and updating forecasts hourly reduces losses from imbalances by 24% compared to daily forecasts.
• Balancing Groups and Aggregators—professional associations of different types of generation (solar, wind, biomass, gas, batteries) that take responsibility for imbalances and act as a single balancing entity for NPC “Ukrenergo.”

D.TRADING’s Experience

The company has already obtained aggregator status, consolidated 767 MW of various generation types into its balancing group portfolio, and manages over 200 MWh of energy storage systems.

The Head of the RES and BESS Projects Department at D.TRADING also answered questions from the moderator and forum participants:

1. Why has the share of RES increased?
   • The growth occurred due to new RES projects as well as a drop in consumption and a reduction in conventional generation. About 200 MW of new wind power plants have appeared during the war. The exact impact of rooftop SPPs is difficult to calculate.
2. How is the payback period for an SPP with an ESS changing?
   • The basic payback period for an SPP is currently about 7 years at the average market CAPEX. But everything depends on price forecasts. According to the capture price indicator, Ukrainian solar in 2025 has a coefficient of 0.6 (40% cheaper than baseload), whereas solar + ESS has a coefficient of 1.1–1.15 (10–15% more expensive than baseload).

According to Yehor Zakharchenko, despite significant challenges, distributed generation and energy storage systems remain the key drivers of change in the market. They provide an opportunity to increase flexibility, reduce imbalances, and open up new possibilities for both large companies and small businesses.

“The 11% share of RES is just the beginning. Further development will depend on how effectively we can work with imbalances and create conditions for investors,” he concluded.