Infundibulum,

I think the most recent "state of the art" solar power generator is a device similar to what you describe--except it's formed from a small array of parabolic mirrors all held on a frame which tracks the sun. The heat beam is concentrated on a stirling engine, which directly produces the electricity.

The main electrical utility in California has already contracted for many thousands of these to be arrrayed in the desert in several locations outside of Los Angelos and San Diego.

Here are some vids about them:

25KW

10KW