The three provided diagrams illustrate the structure of the solar panel along with its functions.
Overall, it can be seen that the solar panel is constructed fundamentally but having different features for the processes of heating air or water.
Regarding the design of the solar panel, it is created with an open box but can be closed by placing a transparent top. Furthermore, there are two pipes at each side of the box which allows air or water to flow in and out.
In terms of heating air function, firstly, cool air in the atmosphere flows through the inlet to the box which has a transparent top in order to hinder the air from releasing out. Inside this box, heat energy from sun rays goes through the transparent top to heat the air. Once the warm air has released out of the box through the outlet, the process of air heating is completed.
Turning to the water heating purpose, similarly, the cool water flows through the inlet to access the box. But at this point, the box is constructed with a water pipe which absorbs heat energy directly from sun rays to heat the water. Subsequently, warm water flows out of the box through the outlet, completing the water heating process.