Consider I have a solar panel setup as in the above picture. The top sketch is sketching sun rays in the early morning around 6 AM in a clear bright sky. The bottom sketch is sketching the sun ray hitting the solar panel at around 8 AM.
I installed a solar panel on a mountain, where we usually see the sun more than 12 hours a day. I found that even if I turn the solar panel to face the early morning rays perpendicularly, it doesn't produce much electricity. But when it reaches around 8 AM with the solar panel to perpendicularly facing the sun, the electricity it produces will increase to almost maximum performance, not very different to the productivity at noon. Quantitatively, this is typically an increase in voltage from around 5V to 16V, of 18V maximum. In this case, it is the same sun, the same place, the same solar panel, and the same condition (it faces perpendicular to the sunray, as in the picture). So what is different in the early mornings here so that the output is so different?