From the article you linked to:
“Katherine Tweed for GTM notes that an average gross cost of a solar energy system is down to $3.21 per watt in Texas.”
You are making an apples to oranges comparison. The devil is always in the details. The article that you are referring to makes no mention of the price of produced electricity per kilowatt hour. And this is the problem with nearly everything written about alternative energy schemes... the articles are almost always misleading in some way... using smoke and mirrors to imply something that is not so.
here is a watt to kwh converter.
http://www.rapidtables.com/calc/electric/watt-to-kwh-calculator.htm