If anything, I'd be surprised that a 1.2 ratio is better than a 1.0 ratio. Although, maybe the fact that an inverter is generally more efficient when loaded closer to its rating compensates for some of the clipping with a higher DC to AC ratio.
On Mon, Jan 27, 2025, 4:04 PM Rebekah Hren via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > I agree with Mike, because you can't change the inverter size in PVwatts* > directly, i*t is just a percentage of the array size based on what ratio > you choose. So if you change the ratio you aren't increasing the array > size. > > So that 1 kW array in your example values is paired with an 660 watt > inverter at 1.5 ratio in the program. > > > > > > > On Mon, Jan 27, 2025 at 1:44 PM jay via RE-wrenches < > re-wrenches@lists.re-wrenches.org> wrote: > >> HI David, >> >> My point exactly. >> >> >> >> On Jan 27, 2025, at 1:35 PM, david quattro via RE-wrenches < >> re-wrenches@lists.re-wrenches.org> wrote: >> >> Jay you are right - that doesn’t make sense because with more PV, the >> system will reach “max AC out“ power sooner every morning and hold it >> longer into the evening >> >> >> >> >> On Mon, Jan 27, 2025 at 12:20 PM George McClellan via RE-wrenches < >> re-wrenches@lists.re-wrenches.org> wrote: >> >>> Probably due to clipping. The panels are generating more energy than >>> the power electronics can process, so that excess energy gets cut off (or >>> clipped). It looks like a 1.2 ratio is optimal. >>> >>> George McClellan | Senior Manager, Technical Sales | REC Americas LLC >>> 735 Tank Farm Rd Ste 130 | San Luis Obispo, CA |93401 >>> <https://www.google.com/maps/search/735+Tank+Farm+Rd+Ste+130+%7C+San+Luis+Obispo,+CA+%7C93401?entry=gmail&source=g> >>> Cell phone +1 805 704 3226 | Fax +1 805 357 6104 >>> www.recgroup.com | george.mcclel...@recgroup.com >>> >>> >>> >>> >>> -----Original Message----- >>> From: RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org> On Behalf >>> Of jay via RE-wrenches >>> Sent: Monday, January 27, 2025 11:56 AM >>> To: RE-wrenches <re-wrenches@lists.re-wrenches.org> >>> Cc: jay <jay.pe...@gmail.com> >>> Subject: [RE-wrenches] PV watts question >>> >>> Caution: This is an external email and may be malicious. Please take >>> care when clicking links or opening attachments. >>> >>> >>> HI All >>> >>> I’m working with a customer who’s pretty savvy and is using PV watts for >>> his design. >>> >>> What I can’t figure out is the kwh/year goes down if he uses dc/ac >>> ration of 1.5 instead of 1.2 which is the default. >>> >>> Hes in Santa Fe NM. >>> >>> .8 ratio= 1663 kwh/yr >>> 1.0 ratio = 1668 kwh/yr >>> 1.2 ratio = 1671 kwh/yr >>> 1.5 ratio = 1623 kwh/yr >>> >>> I was expecting that more PV = more kWh/yr. >>> >>> What am i missing? >>> >>> >>> standard module >>> fixed roof mount >>> 14.08 loss’s >>> 10 degree tilt >>> 180 degrees >>> >>> >>> >>> jay >>> >>> >>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> Pay optional member dues here: http://re-wrenches.org >>> >>> List Address: RE-wrenches@lists.re-wrenches.org >>> >>> Change listserver email address & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> There are two list archives for searching. 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When one doesn't work, try >>> the other: >>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >>> 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 >>> >>> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. 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