The new record percentage set at 3:48 a.m. local time (0148 GMT) compared with a previous maximum of 59.63 percent at 2 a.m. on Nov. 11.
The Iberian Electricity Market’s (Mibel) spot exchange OMIE set the benchmark "pool" price in Spain for Sunday at 10.99 euros ($14.38) per megawatt-hour, its lowest since fixing a level of 6.32 euros for Jan. 1, 2010.
Wind farm plants sways the spot market, because producers can sell it at a considerable discount to electricity generated by burning coal and gas.
REE estimated wind power would decline to about 7,500 MW on Tuesday from 12,113 on Monday afternoon, or enough to meet a robust 30.5 percent of demand.
That forced the pool for Tuesday up to 49.41 euros/MWh, a gain of 9.40 euros from the rate set on Sunday for Monday. REE said that it had to cap wind power output several times on Saturday and Sunday at limits of between 11,000 and 14,979 megawatts.
The grid needs to regulate wind power on very windy days because Spain can export only a limited part of any surplus electricity it generates, and nuclear plants cannot be shut down easily. A minimum number of coal- and gas-powered plants also need to keep ticking over. Producers expect wind power to rise again on Wednesday, a factor that may weigh on the pool when it is next fixed on Tuesday.