This is probably a dumb question but I've been wondering why the fall season is so much worse than the spring season from a solar production standpoint. I always thought that the sun pattern was basically the same on both the autumnal and vernal equinoxes and therefore I'd think that the solar production would be similar. Yet, based on both PVWatts estimates and 4+years of actual experience I can say that, at least in the NYC area, the vernal equinox is far more productive than the autumnal equinox. The expectation varies by about 10% and in practice, the good days in late March will beat the good days in late September by over 20%. Anyone know why that is if the sun's pattern in the horizon is the same and the distance from the sun is the same?
I realize that some of that difference could be due to specific issues that pertain to my array like more leaves for shading in September than March. But that should be fairly minimal and I still see significant differences in the peak production during midday at these two times.
I realize that some of that difference could be due to specific issues that pertain to my array like more leaves for shading in September than March. But that should be fairly minimal and I still see significant differences in the peak production during midday at these two times.
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