The main influence in Texas electricity rates is the fact that most of the electricity Reliant Energy in the Texas power grid is generated from coal powered generators. When the use of air conditioners adds a higher than normal demand to the grid, the back up generators used to make up the difference are powered by natural gas. The use of the natural gas generators adds an extra variable to the Texas electricity market, because it changes in price. As the natural gas used to power the back up generators goes up, that extra cost is passed on to the end user.
To add to the already complicated problem, Texas has a very large percentage of the population of the U.S. so the demand on the existing grid is high. Plus, the total area covered in the state is a huge amount of area so the hardware and delivery systems require more maintenance and materials to continue to offer the power to the public.
When you factor in those things, you can see that Texas electricity rates are effected by a complicated network of issues that are not too common. The citizens of Texas are speaking loudly in an urgent attempt to find a resolution for the difficulties, but solar power in a sunny state is going to ultimately be the answer.