Hi Jay, This is where a modeling program can really help. We use Helioscope to model these (they let you try it for free) and extract the true benefit of the more expensive inverter. Like Jason says, it's really all about the environment, tilt & orientation etc. I have found there is also a psychological component to a customer to see them clipping even if your annual production estimates are right on. I haven't seen evidence that Enphase life is compromised by overpowering them for many hours per day, but we will see over time if that's true. Most of the time for non-ideal roof mounts, we have found that an IQ7 will really lose very little energy annually compared to the IQ7+. Like Jason, we have found no real reason to use the IQ7A.
There are other things to consider. For example, we have a utility that puts fixed limits on the size of a solar system based on AC output of the inverter. Oftentimes, dropping to an IQ7 allows a larger DC system and thus more kWh to be produced. Stringing can change as well. Also, Jason according to the spec sheet you can put 16 of the IQ7 as opposed to 13 of the IQ7+ on each string but maybe I misunderstood you. On Mon, Oct 5, 2020 at 5:42 PM Jason Szumlanski < [email protected]> wrote: > It depends on climate, orientation, and other factors. Here it is really > hot almost all the time. We rarely experience anything close to the max > power rating of a module here. If the orientation isn't ideal, that's > another argument for oversizing. Around here we use 385 and 390W 72-cell > modules on the 290W IQ7+ and rarely see clipping that would outweigh the > advantages and cost-efficiency. Incidentally, early indications from some > low temp coefficient 360W modules show that they do quite well compared to > 385W modules with more standard coefficients this time of year. I need more > data on that to make a real assessment. And modules with low temp > coefficients tend to be pricey. > > I am very comfortable with 1.3x - 1.4x here in Southwest Florida using > standard modules. Elsewhere I would expect the ratio to be somewhat lower. > I have no justification for the IQ7A here at this time. > > P.S. My CED Greentech rep shared some Helioscope data using the IQ7 (not > plus) and 360W 120-half-cell REC Alphas. There is only a marginal advantage > to using the IQ7+ over the IQ7 in that scenario here. I still opt for the > IQ7+ since it is marginally better when considering cost and performance > and it is more compatible/flexible. Since it's the same max quantity per > string, I don't see the point in dropping to the IQ7 for the price > difference. > > Jason Szumlanski > Florida Solar Design Group > > > On Sat, Oct 3, 2020 at 8:08 PM Jay <[email protected]> wrote: > >> Hi all >> >> For those working with Enphase. >> How hard are people recommending pushing the DC/AC ratio? >> >> Enphase has some pretty convincing data that even a 400 watt module on a >> 240watt inverter has very small clipping vs annual production >> >> Given that why would i recommend to a customer the IQ7A at 360va and >> quite a bit more expensive vs the 240va IQ7? >> Location would have something to do of course, tilt, yes. >> But it seems that unless you’re installing a really large module or their >> data is wrong, I’m not sure I see the advantage of the larger inverter? >> >> I’m hoping there will be some counter views. >> >> Thanks >> Jay >> Peltz power. >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> <https://mailtrack.io/trace/link/1e66ec6cd3b2747d2145aba8ea9326b4f61101d7?url=http%3A%2F%2Flists.re-wrenches.org%2Foptions.cgi%2Fre-wrenches-re-wrenches.org&userId=1613865&signature=a99335d33726bdea> >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/[email protected]/ >> <https://mailtrack.io/trace/link/295d53353b27ec5f999b79c92fed393ce3ee3d70?url=https%3A%2F%2Fwww.mail-archive.com%2Fre-wrenches%40lists.re-wrenches.org%2F&userId=1613865&signature=481e602a701a1f2a> >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> <https://mailtrack.io/trace/link/2409c8d017e08bd3b3011f0117e0b14d16af76d7?url=http%3A%2F%2Flists.re-wrenches.org%2Fpipermail%2Fre-wrenches-re-wrenches.org&userId=1613865&signature=74569fb32f8d3170> >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> <https://mailtrack.io/trace/link/3c8d7e6368cee6b21623eb110c8b5ade898c77bd?url=http%3A%2F%2Fwww.re-wrenches.org%2Fetiquette.htm&userId=1613865&signature=86bce5644a4e9223> >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org >> <https://mailtrack.io/trace/link/0f27f65d0c6f272a58e07c51a8dbca7e3c32934d?url=http%3A%2F%2Fwww.members.re-wrenches.org&userId=1613865&signature=8a0f4d03dd25c310> >> >> _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > > -- Mac Lewis *"Yo solo sé que no sé nada." -Sócrates*
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