Simulation of a sollar collector

Hi everyone

I'm a French engineering student and I need to simulate a solar collector in COMSOL multiphysics.
I build the panel with glass, air gap, copper, water and insulation but I have a problem with the simulation.
When I start the simulation there is a problem because the temperature of water does not increase.
In fact, the temperature increase only on the airgap.

Who can help me please?

Vincent