Episodes of negative power prices in Slovenia, Romania spread to workdays

Romania registered the first negative day-ahead electricity price for a workday. The phenomenon, which only used to occur on holidays and weekends, has emerged in Slovenia as well.

In spring and autumn, most of Europe occasionally faces periods of excessive power grid loads. The rapid rise in solar and wind power production and the lack of accompanying energy storage and flexibility capabilities are straining the system at times when demand is low. Advanced electricity markets countered the issue by introducing negative prices.

When prices hit zero or go below zero, the seller delivers electricity without compensation or even has to pay to the buyer, respectively. The phenomenon was normally reserved for holidays and weekends, but more day-ahead markets are now experiencing it for workdays as well.

Downward pressure in Romania from strong inflow of negatively priced electricity via Hungary

Romania saw its first such episode yesterday, on Sunday, in the session for today, Profit.ro reported. Prices in its day-ahead market are negative in five out of 24 periods of one hour, between 11:00 and 16:00.

The country is importing at almost 2 GW via Hungary and exporting at up to 1.5 GW to Bulgaria, the news website added. The article notes that renewable energy producers, especially in Germany, where prices are also negative, are exporting to other markets to ease the impact. They usually benefit from subsidies, so generating electricity isn’t necessarily unprofitable even when they sell at a loss.

In addition, shutting down and restarting power plants can be more costly than paying the other side to take excess output.

The level in Romania went to as low as EUR 6.18 per MWh below zero. But the daily average is EUR 76.54 per MWh. The peak, is EUR 198.16 per MWh, between 20:00 and 21:00, when there is no sunlight and prosumers only consume.

Negative prices turn Slovenia’s HSE into electricity consumer

Prices in Slovenia for today also came in negative between 11:00 and 16:00, which is very rare for a workday, Naš stik reported. Among other factors, the two-day May 1 holiday shortens the current workweek. The lowest, between 14:00 and 15:00, is EUR 6.18 euros per MWh below zero.

In comparison, the lowest price for Sunday on the BSP Southpool exchange was EUR 104 per MWh under zero.

At one point during the Easter holiday, virtually all HSE’s production capacities were offline and the Avče pumped storage hydropower plant was storing electricity from the grid

“Last year, we had 219 hours in Slovenia when prices were negative. This year, we are already at number 72, and we have only just entered the critical period,” said Deputy Director of System Operations of ELES Aleš Donko. The company is Slovenia’s transmission and distribution system operator.

State-owned power utility Holding Slovenske elektrarne (HSE) found itself in an unusual situation during the Easter holidays because of negative prices.

“For a while, we were actually an energy consumer, not a producer, which is our core mission… Virtually all our power plants were shut down, and the Avče pumped storage hydropower plant was pumping water into the upper reservoir at full capacity,” Head of Operation Planning and Management Jernej Brglez said.

Portugal and Spain, which suffered major outages today together with France, both registered negative prices every day in the third week of April.

Also of note, Greece is preparing to introduce negative prices in the balancing market.