Other people have responded about circumstances where hydrogen-as-fuel (or fuel component) might still make sense; without commenting on that, it's important to also note that hydrogen is an important industrial feedstock, independent of its potential energy applications (it's critical to producing fertilizer, among other things), and industrial hydrogen pretty much all comes from natural gas at present. Given that we need at least some hydrogen anyway, figuring out better ways to produce it is worthwhile.
In that scenario, total levelized cost is the more important criterion that efficiency -- if these things convert solar energy less efficiently, but the contraption is cheaper than solar panels plus conventional electrolyzers because it's simpler or uses cheaper materials or whatever, it might still be the more economical bet.
In that scenario, total levelized cost is the more important criterion that efficiency -- if these things convert solar energy less efficiently, but the contraption is cheaper than solar panels plus conventional electrolyzers because it's simpler or uses cheaper materials or whatever, it might still be the more economical bet.