Direct two-tank thermal storage and indirect two-tank thermal storage

Hello paul,

I ask you, what is the advantages of Direct two-tank thermal storage over indirect two-tank thermal storage, and what is the best for use ???

and thank you

Dear Mohamed,
Please see the NREL Troughnet website for general information about CSP systems.
Here's a link to the page about thermal energy storage that discusses indirect and direct two-tank systems and provides links to additional information:
NREL Troughnet - Parabolic Thermal Energy Storage
Best regards,

Paul.