Whatever happened to color-changing roof tiles that absorb heat in winter and reflect it in summer?

The article is from 2009. It presents new roof tiles that become black in winter in order absorb heat from the sun, and white in summer to reflect it. I still can't buy these as far as I'm aware. What happened to that? They do write

Savings from the black state in winter have yet to be quantified.

So maybe it turned out that it wasn't worth it compared to tiles that are white year round?