Actual USA electricity generation in 2012 of 4,047.7 Terawatt hours. http://en.wikipedia.org/wiki/Electricity_sector_of_the_United_States
Divide by 365*24 and get 462 Gigawatts per hour 462,000,000,000 watts
Area of Texas = 268,820 mi² or (696,241 km²) 696,241,000,000 square meters
The standard solar panel has an input rate of around 1000 Watts per square meter.
Now; do the math...
So at the current rate of use even the state of Texas wouldn’t be enough!