I think you mean 12pm and 3pm. So if your assumptions are correct, the same should hold true for 9am to 3pm or even a bigger time gap with proper angle. Also we would need to establish the true sensitivity of the cheap solar panel or other measurement device being used, which is quite difficult in relation to the sun.

In either model, the distance to the sun changes as the earth rotates or as the sun moves away, but as we know if the sun is truly 1au it would be much harder to measure any difference via energy delivered.

I prefer to look at the size of the sun grow bigger from morning to midday & smaller from midday to dusk. It is a simple thing to do with a Timelapse similar to this one

If the sun is actually 1au away the size should not change so obviously & consistently imo. However, no one observation or experiment is sufficient to provide proof to someone who is already convinced of the outcome either way. I genuinely strive to be open minded on the topic, but am admittedly highly skeptical of the mainstream narrative.