It's nearly all wind, whose output fell all the way to 12.5% of installed capacity over a three-day period when homes were freezing (February 15, 16, and 17). [0] Output consistently stayed in the 15-30% range while I was watching it in ERCOT's live stats. Solar plants are nearly a rounding error. Every other source maintained 60-75% of capacity even with insufficient winterization.
[0] http://www.ercot.com/content/wcm/lists/181766/IntGenbyFuel20...