(KTEN) -- Like many Texomans, the Nelson family has spent many of the last 48 hours in the dark during a fierce and bitterly cold winter storm.

"Our electricity was off for 30 hours," Penny Nelson said.

That makes it impossible to cook or boil water for safe consumption... all while doing their best to stay warm as outages continue.

"It is unacceptable," said Bill Magness, CEO and president of the Electric Reliability Council of Texas.

ERCOT responded to criticism Tuesday as millions of Texans continued to face below-freezing temperatures with no power.

Magness said the choice to initiate rolling power outages was critical to avoid overwhelming the power grid, which ERCOT controls in most of Texas. 

"We saw a large drop in the amount of supply available, and if we had left that supply and demand balance stay too long out of balance, it could have had catastrophic impacts on the grid itself," he said.

ERCOT directed utility providers to begin the rolling blackouts, and told them how much was needed to cut back. Ultimately, the provider decides where and how long connections are cut off.

"It's really just up to those transmission companies to decide those things," said ERCOT's senior director of system operations Dan Woodfin.

ERCOT is working to generate enough power to maintain the balance of the power grid, but could not answer when normal operations would resume.

For the Nelson family, the most unbelievable part is that it happened with practically no warning.

"They didn't say anything about, 'You're going to lose power for so many days or so many hours.' It just went out, with no notification," Randy Nelson said.

"Now we're on like, an hour on, an hour off," Penny Nelson added.