UK day-ahead power prices rose sharply on Monday in thin trade, extending last week's gains on tightened supply margins, one source said.
On the OTC market, baseload power for Tuesday delivery was last heard trading at GBP53/MWh, up GBP8.05 from Friday's assessment for Monday power.
The day-ahead peakload power price saw stronger gains of GBP13 to trade at GBP66/MWh before Platts 11am London time close.
Meanwhile, the UK base day-ahead auction outturned above the OTC price by more than GBP1 at GBP54.34/MWh on N2EX and APX exchanges on Monday.
It is a "very quiet day in terms of prices and liquidity," one trader said, adding that the "market tightness within day" helped push prompt prices higher.
UK transmission system operator National Grid expects peak demand to reach 48.5 GW for Monday, and further increase to nearly 49 GW on Tuesday, while surplus margins are set to remain below 7.5 GW this week.
Peak wind power generation is forecast to decline by more than 1 GW on the day to 2.3 GW on Tuesday, down from Monday's maximum wind output of 3.8 GW, which would likely curb supply.
At midday Monday, wind output came in slightly below initial estimates at 2.2 GW, representing 5.6% of total electricity supply.
This was offset by an increase in nuclear generation, which rose to 5.4 GW at midday, up from less than 5 GW seen in recent weeks, after a nuclear plant was reconnected to the grid.
On Monday, EDF Energy said it had restarted the 485 MW unit 8 at its Hunterston B nuclear plant on Sunday after the plant was shut down in early October due to turbine issues.
Further on the supply side, coal became the dominant source of energy in the UK on Monday, surpassing gas to produce 35.8% of the UK's total supply at 14.4 GW.
Gas-fired power generation at 12.7 GW, accounted for 31.5% of the fuel mix, the grid data showed.
Power generation from solar and hydro stood at 656 MW and 785 MW respectively at midday Monday.
