TXU Energy and Reliant Energy have begun offering electricity pricing plans that charge more for power consumed during peak use times and less during low-demand times.

The companies only offer the pricing plans in neighborhoods where Oncor has installed advanced meters. The new meters can tell electric companies how much power a customer uses every 15 minutes, allowing companies to charge different prices throughout the day.

Electricity industry officials expect such pricing plans, known as time-of-use pricing, to prompt customers to dial down power use during the late afternoons, when power plants are running at full tilt and wholesale power prices spike.

TXU charges 8.9 cents per kilowatt-hour for electricity used off peak. Power used during peak times – such as midafternoon during the summer months – costs 24.3 cents.

TXU time-of-use customers also get a free thermostat that shows how much power they are using. Customers may decline the thermostat and get a $75 Visa gift card instead.

TXU spokesman Tom Stewart declined to say how many people have signed up.

Reliant has a more complicated system. The off-peak rate is 11.7 cents per kilowatt-hour. In the winter, Reliant charges 13.9 cents between 6 and 9 a.m., and again from 6 to 9 p.m.

In the summer, the 13.9-cent rate is in effect from noon to 4 p.m. weekdays; then the rate rises to 14.4 cents until 6 p.m.

Reliant set its time-of-use prices in July, and plans to update them in coming weeks.

"We've had some success signing up the time-of-use customers. So we have seen interest in the product," said Reliant spokeswoman Pat Hammond. She said the company sends customers a weekly e-mail outlining their usage.

These are still early days for pricing plans that depend on the new meters. Relatively few people in Texas have them.

Oncor has installed about 300,000 meters. The company will finish installing the meters at every business and residence in North Texas in 2012.

The regulated power line companies in other parts of the state haven't begun to deploy the new technology.

The time-of-use rates are designed to attract customers who are away from home during the day and therefore use very little juice during peak hours.

Customers offered the time-of-use plans can opt to stay with variable or fixed-rate plans. And with or without a meter, customers can find cheap rates all day long. On Friday, some companies were offering fixed rates for the next 12 months as low as 10 cents per kilowatt-hour.