Power use broke records and the lights stayed on

conserve energy throughout the hottest part of the day, 3 p.m. to 7 p.m., by doing things such as closing drapes and blinds in rooms that get direct sunlight and grilling dinner outside instead of using the oven.

In the Houston area, several retail electricity providers sent out email alerts asking their customers to turn off pool pumps, turn up thermostats and refrain from using washing machines, dryers and dishwashers during the late afternoon hours when power use peaked — and wholesale prices were at their highest.

“It was pretty clear we were getting to the point we were strained,” said Ed Hirs, energy economist at the University of Houston.

Power use hit 72,192 megawatts on July 18, surpassing the previous 2016 record. The following day Texas set another all-time, systemwide peak demand record, topping out at 73,259 megawatts between 4 p.m. and 5 p.m. One megawatt can power about 200 homes during a hot summer day in Texas.

NRG Energy said information about how its retail companies supplied customers in July won’t be made public until the company announces its third quarter earnings in the fall. But NRG spokeswoman Pat Hammond said its request to customers to conserve power was made to protect the integrity of the power grid, knowing how hot it would be and how much it would strain electricity supplies.

DeAnn Walker, chairman of the Public Utility Commission, said her agency is already examining how ERCOT handled the hot weather demands this summer.

“The summer season is halfway over,” Walker said in a statement, “but we anticipate continued reliability,”

One former power trader said it appears ERCOT encouraged generators to operate their plants at maximum capacity and sell the power on what’s known as the “day ahead market,” a financially-binding forward energy market where generators agree to sell their power at a contracted price on the following day.

That caused day-ahead prices to rise, which in turn spurred generators to produce more electricity, said Trent Crow, who left trading to launch the electricity shopping service Real Simple Energy.

“At those prices every single power plant is making money,” said Crow, noting that the price per megawatt hour in the day ahead market hovered between $1,400 and $2,000 during the hottest afternoons last month, compared with typical prices of $100 to $200.

Photos by Melissa Phillip / Staff photographer Wells Fargo CEO Tim Sloan, a three-decade veteran of the bank, took over as CEO in October 2016.

Kin Man Hui / Staff file photo The Electric Reliability Council of Texas didn’t issue pleas to consumers and businesses to conserve power, but a number of local utilities did.