I did a similar test today at clock noon and 52 degree sun angle. The sky had just a tiny bit of haze whereas yesterday was very clear. You might think haze or light cloud just reduces the solar energy to the panel, but it also causes some reflected radiation from the haze or cloud and reduces the effect of angling the panel. Today the output was 260 watts with the roof flat and 285 watts with the roof angled up. My camper is a Grandby, so the roof slope with one end up is about 2/12, or 9.5 degrees. A Hawk would be steeper at 24/80, or almost 17 degrees, so a Hawk would get more benefit from tilting the roof of a level camper toward the sun.