The Electric Reliability Council of Texas (ERCOT) does it for you. When you sign up for a plan with a new provider, ERCOT will send you a mailer confirming the switch. You have three days upon receiving the mailer to change your mind. If you don't, you'll have a new provider within seven days, and ERCOT will notify your old provider. Just remember, if you abandon a contract before it's complete, you will be on the hook for any fees or penalties detailed in its Terms of Service.
In this free market competing electricity retailers buy electricity wholesale from private power generators to sell at retail to around 85% of Texas residents. The partnership between generators and retailers is governed by the Electric Reliability Council of Texas, or ERCOT, which attempts to balance the power grid’s electricity supply and demand by purchasing small amounts of electricity at 15-minute intervals throughout the day.