Minimum Temperature for Small Steam Turbine

You might be able to run a small toy engine or turbine from a solar furnace. Mind you, I said furnace, steam engines,especially turbines are real hungry. Of course, you are going to be above boiling by a good point to get power.

The real tough part in any steam project is pumping water to the boiler. The pump must be capable of pressure above boiler pressure for continuous use. Controlling the pump and the boiler require a lot of studying, don't just jump into this project. You can really blow up big time. A small boiler the size of an orange can take your hand off.

Do plenty of library time before you do anything. Steam has a bad history, does not tolerate errors. Scalds can leave permanent scars, and proper equipment is hard to find.