Here are the results of a simple sun-angle test I ran yesterday. Final chart here: http://i39.tinypic.com/t4xpab.jpg Tom http://www.youtube.com/user/Fearlessthinker
How about a vertical test using sun angle at your house for this time of the year. Then move it away from that angle to show the drop off. Just a thought...
The PV doesn't care if the angle is east-west or north-south relative to the sun, so the result should be the same, unless I don't understand your suggestion.
Minnesota Do you think that you got better results in the west because the inverter was warmed up. I wonder if you would get the same results going west to east. Mine seem to perform better once up and going and hold longer before droping off. Just a thought.