1.) Thermal only works on a massive scale. You can't fit 1000 large mirrors, a tower, a huge turbine, and the requisite plumbing on a commercial rooftop.

2.) Even if you could, the city wouldn't let you because the mirrors would distract aviation and anger neighbors.

3.) Technological advances and a capacity glut in PV manufacturing brought the price of panels down so far that it doesn't make economic sense to build thermal anymore.