Solar steam engine from 1936

there are a few examples of modern day concentrated solar power outfits on the good old wikipedia.

looks like the first patent for a solar steam engine was given in 1886 while the first one was built in 1866.

I can't imagine that obtaining the materials involved is ecologically benign, but I suspect that these might beat photovoltaics when considering negative impacts.

This is a cool concept.  I have recently been looking at parabolic mirror boilers on Youtube, some of them are totally DIY and made with recycled/salvage material.  One fellow in Colorado made a large parabolic array that runs a 12kw generator.