Hi @bk19110254 , I ran your geometry with the new Immersed Boundary solver. It creates a cartesian mesh, and therefore it is very stable and fast. You can find my simulation here. I applied the symmetry boundary condition as an adiabatic and no-slip wall for the solids and an adiabatic, slip wall for the fluid. In your simulation you defined the wall of the solar PV also as a heat source. I defined the heat source in my project a little differently. I calculated the total power by measuring the area and multiplying it the heat flux (1100) you provided. This amounted to a total power of 336 W which I applied as absolute power source (found in Advanced Concepts). You can find more information on the Immersed Boundary Method in SimScale here: https://www.simscale.com/docs/analysis-types/immersed-boundary-analysis/
Here are some images from the simulation run:
