Demand reached a record 69,783 megawatts on Monday, topping the previous records of 68,912 MW set on Aug. 6 and 68,459 MW on Aug. 5, the Electric Reliability Council of Texas (ERCOT) said in a statement. ERCOT is the grid operator for most of the state. 

Before the latest heat wave, the grid's previous peak demand was 68,305 MW set on Aug. 3, 2011. One MW is enough to power about 200 homes during periods of peak demand.

"Demand is expected to remain high until temperatures begin to break at the end of the week," said Dan Woodfin, ERCOT director of System Operations.

Temperatures in Houston, the biggest city in Texas, have topped 100 degrees Fahrenheit (38 Celsius) since Sunday and were expected to remain at or around triple digits Fahrenheit through Saturday, Aug. 15, according to weather forecaster AccuWeather.com.

"Our focus continues to be on ensuring we maintain overall reliability and protect the grid, while having sufficient generation in place to meet demand," he said.

There are more than 73,000 MW of generation in the grid, according to the ERCOT website. ERCOT said the region's more than 13,000 MW of wind generation contributed up to 2,400 MW during Monday's peak.

Some of the biggest power companies in Texas include units of Energy Future Holdings, CenterPoint Energy Inc, American Electric Power Co Inc, NRG Energy Inc, Exelon Corp and NextEra Energy Inc.