How does vacuum tube solar water heater work?

As it’s compact system, the vacuum tube is connecting with the storage tank directly and there’s water flow inside the vacuum tube. So it’s working as cold & heat convection.
                                        
                                     How does heat pipe solar water heater work?

The solar collector absorbs sunshine and transfer heat through heat pipe which inside the vacuum tube to the condenser. And during the water pass the manifold, it will bring the heat away from the condenser. And hot water will flows to storage tank by a cycle pump.