sort of flash steam system? sunlight might have 350 btu/hour hitting the earth. at 10', 35 of those dishes would get you 16 hp to use the same wood fired boiler metric, assuming perfect reflection, all other efficiencies being equal. there is a lot of waste in the conversion to steam then mechanical then electrical - why not photovoltaic or some such thing? i know they are expensive, but so are 35 10' dia parabolic dishes. 800 degrees is not to be trifled with, then again flash is less dangerous than a boiler i believe. maybe it could run a turbine instead of a steam engine.
if its running a fridge, you don't need 10+ hp. start small and simple, figure out the math an engineering, understand the safety concerns of pressurized steam vessels and see what you come up with. the quantification to assess the idea was like 2 minutes of googling so don't take it as gospel or proper engineering, time for the builders to do their homework and hopefully convert this from idea to reality.