I have been planing a home based solar power system for a little while now, and although I know I can get nearly limitless solar power in the form of mineral oil at temperatures greater than 450F I am having trouble finding a heat engine to build with off the shelf parts. A full steam cycle seems to be the ideal solution, and the one I am most familure with, but I am at a loss as to what to use as an engine/turbine. My one solid idea is to use a modified scroll compressor as an expander to drive a car alternator. That way I could use multiple stages and multiple expanders to keep efficiency up through varying power outputs. Does anyone have any practical knowledge of scroll expanders or an other solution? Any help would be appreciated, thanks.