An American PM Research 'Solar 1'
And a Chinese Maidstone Engineering Stirling Engine
They both run brilliantly, but the quality of the two engines is a world apart. The Chinese engine is out of square and wobbles about the place when running, the American engine is quiet and smooth. Both engines are still readily available with the PM Research from Forest Classics at £115 and the other from Maidstone Engineering at £95. For the money - I know what I'd have!
I'll try get a video of them in operation in the next few days - lot's of coursework on at the moment though!