As side-by-side tests of smart meters and analog meters continue to show no differences, state regulators are looking into how the data gets from the meter to electric bills.
Customers who have been switched to the digital power meters have complained, saying their electric bills have doubled or even tripled.
Oncor Electric Delivery has blamed the higher bills on the unusually cold winter season.
Oncor, which is replacing more than 3 million of the old analog meters in North Texas with smart meters, has conducted side-by-side comparisons of the digital meters with the traditional analog meters in the Dallas area, Killeen and Temple. The readings from the smart meters have shown little to difference to those from the analog meters, the utility says.
The Public Utility Commission decided at its meeting in Austin on Thursday that the independent company it has hired to test the accuracy of smart meters will also test the system that processes the data coming from the meters.
Some people with smart meters are taking steps to get their bills back to where they once were, such as turning up their thermostat and turning off some of the lights in their homes.
Leigh Butler, a single mother, said just cooking dinner for her family is now a concern. She said she has constantly worried about how much electricity she is using since Oncor installed a smart meter at her home in December.
"You feel helpless," she said. "What are you going to do? People are on a budget."
Butler said she noticed a difference in the first bill she got after the installation. She said the kilowatt usage on her bills have bothered her the most.
She said she has been billed for 4,000 kilowatt hours in her 1,800-square-foot, one-story home with three children. But in when she lived in a bigger home -- nearly 3,000 square feet -- in July 2008 with five children, she used 3,500 kilowatt hours.
"It just doesn't make sense," Butler said. "It's not possible."
She said she was happy to hear the PUC had ordered addtional testing of the digital meters.
"Something needs to be done," she said. "Something is not right. We can't afford to be cool. We can't afford to be warm."
Navigant, the independent testing company hired by the PUC, said it will take about three months to test and analyze all of the data for the smart meters.