The costs associated with photovoltaic systems have decreased significantly in the past fifteen years or so, and I would say they are the competitor to solar thermal systems.
As well as storing heat, they can be used for thermal desalination at the same time as power generation. I haven't seen a breakdown in costs of this system versus something like reverse osmosis, so I can't really say if it's better or worse, but I'm sure there's places that find it useful to have a combined solution to water and power.