In this system, we don't store solar energy in batteries ... we store solar energy in the form of heat, and the method is to heat salt or oil and store it in gas geyser type thing that keeps its heat at night. this system can run direct but no use, as we need constant steam pressure. and u will be wasting lots of heat as water boils at only 100 deg. thus u need something that will store heat up to 500 degree. and use some of it to boil water.
Now, steam engines are big problem. u cant get one small enough for prototype project and large steam turbines are expensive like crazy.(not to mention they need much larger solar setup).
so if u can make small steam engine or turbine. your half work is done.