This graph shows how the middle absorber panel on the Dave House South compares to the stagnating panel on the outside of the office. Both panels are mounted vertically on South facing walls. The stagnating panel temperature is fairly close to the sol-air temperature during the day. Even though the panel has a selective surface coating, the sol-air plate is tilted which roughly compensates for the difference in emissivity. At night, however, the difference in emissivity and the tilt work together to cool the sol-air plate more than the stagnating panel.