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From what I've read, clipping is negligible in the long run. However, after less than a week's output, I see some clipping occurring already. Nothing big, at least not so far. I started wishing I had done a bit more research on the microinverters and used the IQ7+ (290W) instead of the IQ7 (240W) with my 330W panels. My AC/DC ratio is 1.38.
However, I started doing some math. Inputting this data into PVWatts, I get an annual difference of 239kW between the two microinverters. At $0.20/kWh, that's about $50/yr. Not big, but at only $15 more for the IQ7+, that's an 8 year payback on the difference between them, assuming electric rates don't increase (which they will). Keep in mind, the string is limited to 13 micros vs 16, so some cable planning needs to take place beforehand.
A better option would be to spend the extra $360 on an additional panel and microinverter, assuming you have the room to do so. This gives an increases the PVWatts estimate of 582kWh/yr (vs the 239kWh of the IQ7+).
Bottom line, after initially being upset and reading a bunch of articles and forums on clipping, it's best just to run the PVWatts estimate. If I were to do it over again, I'd use the IQ7+ and center feed the array to make using two strings easy. An 8 year payback on a system that will be in place for 20+ years is worth it in my opinion. But, the difference really is negligible, and if you have the space and a set budget, adding just one more panel is a better ROI than paying for a higher rated micro. I'm less familiar with string-based systems, but I assume the same logic would follow. YMMV.
However, I started doing some math. Inputting this data into PVWatts, I get an annual difference of 239kW between the two microinverters. At $0.20/kWh, that's about $50/yr. Not big, but at only $15 more for the IQ7+, that's an 8 year payback on the difference between them, assuming electric rates don't increase (which they will). Keep in mind, the string is limited to 13 micros vs 16, so some cable planning needs to take place beforehand.
A better option would be to spend the extra $360 on an additional panel and microinverter, assuming you have the room to do so. This gives an increases the PVWatts estimate of 582kWh/yr (vs the 239kWh of the IQ7+).
Bottom line, after initially being upset and reading a bunch of articles and forums on clipping, it's best just to run the PVWatts estimate. If I were to do it over again, I'd use the IQ7+ and center feed the array to make using two strings easy. An 8 year payback on a system that will be in place for 20+ years is worth it in my opinion. But, the difference really is negligible, and if you have the space and a set budget, adding just one more panel is a better ROI than paying for a higher rated micro. I'm less familiar with string-based systems, but I assume the same logic would follow. YMMV.
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