Efficiency, Heat Loss
The temperature on the array varies greatly from the ambient air temperature. The panels are only about 10 percent efficient, and they give off 90 percent of the energy they receive as excess heat. This means that the temperature directly above the panels can be significantly higher than the temperature outside. High temperatures also affect the efficiency of the array; the panels operate better at lower temperatures.
Such high temperatures can heat the building to an uncomfortable temperature during the summer, as heat rises towards the open windows. To prevent this, a specially-designed baffle across the top of the panels redirects air outwards and away from the windows.