Concentrating Solar - Why so little advances?

In the past 17 years, there does not seem to have been a lot of advances in Concentrating Solar. R&D is an area I would have hoped would have been continued to be funded by the government, even with low natural gas prices in the past. But, reality of course not, that would be thinking to long term. And now without the renewal of the tax credits for solar, new installationsof Concentrating Solar in the US are threatened.