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 < [email protected]> wrote: > HI David, > > My point exactly. > > > > On Jan 27, 2025, at 1:35 PM, david quattro via RE-wrenches < > [email protected]> 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 < > [email protected]> 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 | [email protected] >> >> >> >> >> -----Original Message----- >> From: RE-wrenches <[email protected]> On Behalf >> Of jay via RE-wrenches >> Sent: Monday, January 27, 2025 11:56 AM >> To: RE-wrenches <[email protected]> >> Cc: jay <[email protected]> >> 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: [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. 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Thank you. >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> 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. 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