In what is becoming an almost daily occurrence, ERCOT on Sunday issued another appeal for voluntary conservation as the Texas grid operator continues to manage tight conditions during a brutally hot summer.

The ISO called for the market’s consumers and businesses to reduce their usage between 4 p.m. and 9 p.m. (CT). As it has since late last week, ERCOT warned of the potential to enter emergency operations because of high demand paired with expected low wind and possibly low solar generation during the evening hours when the sun sets.

The conservation call marked the fourth straight day, and seventh overall, the grid operator has asked for voluntary conservation this summer. Temperatures reached a record 109 degrees Fahrenheit in Houston and broke triple digits throughout much of the rest of Texas.

“What we’re seeing are conditions that are more tight than what we have seen on any other day this summer,” ERCOT CEO Pablo Vegas told the Public Utility Commission during an open meeting Thursday. “At this time, it’s a high likelihood that we expect to be in emergency operations this evening.”

That did not happen. The grid operator deployed its newest ancillary service, ERCOT Contingency Reserve Service (ECRS), and non-spin reserve service to close the gap between supply and demand. Pop-up rain showers in the Houston area also lowered temperatures and with it, demand — but not before an hourly average peak of 84.24 GW, more than 1 GW from a record.

ECRS dispatches resources that can respond within 10 minutes of deployment instructions and can operate for at least two straight hours. It also was deployed Friday and Saturday along with non-spin and responsive reserves; energy storage regularly supplied more than 1.2 GW of energy as well.

“Thank you to Texas residents [and] businesses for your conservation efforts, which along with additional reliability tools, helped us to get through a tight peak time,” ERCOT tweeted Thursday night, a message it has repeated several times since.

Vegas told the commission the ISO has seen a “very different profile” for wind energy, with an afternoon production of about 6 GW that is several GW lower than normal during summer months. He said the thermal dispatchable fleet has been operating at or near normal forced-outage levels.

“It’s really the combination of the very high heat, the very high demand and the low expected output of wind during the solar ramp,” Vegas said.

Temperatures are expected to cool slightly in Texas this week. ERCOT’s six-day forecast predicts demand to stay below 79 GW for the rest of the week.

The grid operator’s record for hourly average demand remains 85.44 GW, set Aug. 10. It has broken last year’s high of 80.15 GW 193 times this summer.

ERCOT staff had projected a summer peak of 82.7 GW in its final pre-summer assessment. That mark has been exceeded 98 times this summer.