Thermal air panels almost always work better on walls, not roofs. Mounted on an angled south facing roof the summertime stagnation temps could easily exceed 200F, maybe even 300F. Mounted on a wall there is better convective cooling, and a large fraction of the mid-day solar radiation is reflected due to the high angle of the sun.
Any solar air panel should have both a backflow preventer flap or valve and a louver or register for shutting off the output for stopping convection currents when heat isn't wanted. With an active blower version a standard closeable hot-air furnace or AC register well enough for blocking the unwanted hot air flow.