A new Slovak record has been set. Negative electricity prices have broken through -200 euros/MWh.

Almost to the day, Slovakia is rewriting the statistics of the daily electricity market again after a year.

While last year, on May 12, 2024, the price of electricity fell to an unprecedented -146 euros/MWh, the day before yesterday, on May 11, 2025, it fell even deeper. Below the -200 euros/MWh mark.

We took a closer look at the figures published by the organizer of the short-term electricity market, the state-owned company OKTE. The price development on individual days since the beginning of this year is summarized in the graph below in the article.

What's happening on the daily market
Negative electricity prices and greater volatility (variability) of prices are an increasingly strong phenomenon on the spot electricity markets. While in 2023 the price of electricity on the Slovak daily market was below zero for two hours, in 2023 there were 90 such hours. Last year there were almost 300.

And although last year rewrote the statistics, this year started even "wilder."

As we reported on Energie-portal.sk after Easter, since the beginning of 2025, the number of hours with a negative electricity price has increased year-on-year and electricity prices have also begun to fluctuate more significantly. Both in the positive and negative directions.

This year's record in the positive direction continues to be held by January 20 and 21, when electricity on the OKTE daily market was briefly traded for more than 500 euros/MWh. In both cases, these were working days (Monday and Tuesday).

On the contrary, the price of electricity traditionally drops to negative values ​​this year during weekends and holidays, i.e. days of rest associated with lower electricity consumption. Extreme drops occur mainly in situations where this low demand meets with a large supply. For example, thanks to sunny weather, which favors the production of photovoltaic power plants.

The drops in electricity prices gained intensity this year during May. Since the beginning of the month, electricity on the Slovak daily market has been traded with a negative price for 42 hours so far (as of May 13).

The first steep drop below 0 euros/MWh came on the public holiday of May 1, when the price of electricity broke through the level of -100 euros/MWh, similar to the same day a year ago. On this day, the buyer was de facto paid for the electricity consumed between 10:00 and 17:00.

As the graph, which captures the entire time course, shows, an even bigger drop came 10 days later, on Sunday, May 11. Electricity was first “sold” for exactly -200 euros/MWh in one trading period (2:00 p.m.) and then (3:00 p.m.) for -202.70 euros/MWh.

The phenomenon will weaken, believes an EY expert
Although the trend of negative electricity prices associated with the rapid development of renewable energy sources (RES) has been growing across virtually all European markets in recent years, there are also opinions that the number of hours with negative electricity prices will begin to decrease in the foreseeable future.

Such an attitude was presented at the recent conference Days of Heating and Energy by Blahoslav Němeček from the consulting company EY, for example. The gradual ending of support schemes in Germany and the Czech Republic will lead to a reduction in the number of hours with low or negative electricity prices.

"The incidence of negative hours may still increase in the short term. Then there will be a slowdown, although they will not disappear completely. It will always be a tool to get rid of the surplus, but there will definitely be no motivation to produce, because producers will not collect any support," he thinks.

Complication and opportunity
In the current situation, when negative electricity prices are increasing and at the same time the so-called price spread between positive and negative extremes is increasing, new challenges and opportunities are emerging on the market.

Frequent drops in electricity prices below zero can be a complication, for example, for many investors considering RES projects. Negative electricity prices can in many cases worsen the return on investment plans or make it more difficult to predict, especially in cases where their business model does not include operational support and guaranteed prices.

On the other hand, the trend of negative prices can be a new opportunity for battery storage systems (BESS). While in the past two years the battery market in Slovakia has largely been driven by the interest of investors in providing support services, large price spreads open up other possibilities.

“Whether the battery will be used for arbitrage on the intraday market or for time shifting from photovoltaics, the size of the market will in principle correlate with how many renewable sources are connected to the system,” explained Tomáš Rajčan from IPESOFT at last year’s SPX conference.

In addition, customers who have electricity supply contracted in a dynamic product with a spot additive can benefit from the more frequent occurrence of negative prices. Provided that they can flexibly adapt their consumption to price developments.

"If you have the highest consumption on these days, or if you can adjust the consumption times, this will have a positive impact on the average price of the supply. A very useful tool is smart metering, which will help to understand the consumption point, down to the level of individual appliances. Then this data can be actively used to optimize consumption and energy purchases," explained last year, Prva Energeticka analyst Andrej Lednár.