wwhitney
Active Member
OK, I'm no PVWatts expert (I don't know if there is a way to enter two different arrays simultaneously), but with those panel orientations, clipping appears to be a non-issue for you. I just looked at the two orientations separately, and compared the program results with DC/AC of 1.0 to DC/AC of 1.5, leaving everything else at default. No difference at all.
[If there had been a difference, treating the two orientations separately would have been a definite underestimate, because it ignores that one orientation might be using less than its proportional share of inverter capacity, allowing the other orientation to use more that its proportional share and avoid clipping.]
Basically, your panel orientations are so far from optimal, your panels are never going to produce close enough to their nameplate values that you'll have any significant clipping at all. Go ahead with 15.5 kW DC and a 10 kW inverter. [With a more sophisticated analysis, you could probably justify going to 16+ kW, based on your panel orientations, but I don't have the ability to do that analysis easily.]
Cheers, Wayne
[If there had been a difference, treating the two orientations separately would have been a definite underestimate, because it ignores that one orientation might be using less than its proportional share of inverter capacity, allowing the other orientation to use more that its proportional share and avoid clipping.]
Basically, your panel orientations are so far from optimal, your panels are never going to produce close enough to their nameplate values that you'll have any significant clipping at all. Go ahead with 15.5 kW DC and a 10 kW inverter. [With a more sophisticated analysis, you could probably justify going to 16+ kW, based on your panel orientations, but I don't have the ability to do that analysis easily.]
Cheers, Wayne