Hi Vince, Your math looks correct of course, but I think you left out a variable in that the panel won’t be operating at max power because the inverters are all less than 400 watts rated. Which means that the MPPT voltage will be pushed up to reduce power giving you added room.
From my understanding of how the Mppt works, but I don’t know specifically about enphase, if its a good algorithm the inverter won’t go below its lowest MPPT voltage. The inverter will reduce power playing around with the IV curve to maintain the MPPT within its range. So it won’t ever get out of operating unless it can’t even produce enough volts to make that voltage. I’ve never seen a curve of Enphase MPPT efficiency vs input voltage. Would like to though. Jay > On Sep 24, 2024, at 8:38 PM, Vince McClellan via RE-wrenches > <re-wrenches@lists.re-wrenches.org> wrote: > > Hello Wrenches List > I've recently become aware of an issue with micro-inverters that I would like > to share. > Be sure the solar module you're using is compatible with the microinverter > for the solar module's full life. > A good best practice is to design for the MPPT voltage range of the inverter. > I only consider the operating range of the inverter when it won't affect the > inverter during its operational time, such as when the solar module is at its > coldest in the first few moments of sunlight when it hits max Voc. That will > only happen for a few moments as the sun heats the solar module. High heat is > different. If the solar module falls below the MPPT voltage window that will > happen in the middle of the day when the solar array should be producing its > maximum power for the day. If the voltage of the solar module falls below the > MPPT voltage window during that time it becomes much less efficient at > tracking the power or simply turns off. Some studies have shown a solar > module degradation rate averaging up to 1.4%/year. > > Here is an example of what I'm talking about with weather data for Eugene OR > and a roof-mounted Phono PS400M6H-18/VHB solar module. > Vmp 30.85 > Coe/°C = -0.28% > High-Temperature voltage calculation: 30.85 Vmp X [ 1-(32+30-25) X .0028] = > 27.65 Vmp adjusted for 2% average high temp of 32°C > Here is my Enphase cheat sheet for quickly looking at design compatibility. > Enphase M# Operating Range MPPT Voltage Range Commonly used module > pairings Phase > IQ8MC-72-M-US 18-58 V 25-45 V 260-460 Wstc 1 > IQ8-60-M-US 16-48 V 27-37 V 235-350 Wstc 1 > IQ8PLUS-72-M-US 16-58 V 27-45 V 235-440 Wstc 1 > IQ8H-3P-72-E-US 16-63 V 28.5-45 V 320-540 Wstc 3 > IQ8M-72-US 16-58 V 30-45 V 260-460 Wstc 1 > IQ8A-M-US 16-58 V 32-45 V 295-500 Wstc 1 > IQ8A-72-M-US 16-58 V 32-45 V 295-500 Wstc 1 > IQ8P-3P-72-E-US 16-63 V 35.5-53 V 380-640 Wstc 3 > IQ8H-208-72-M-US 16-58 V 36-45 V 295-500 Wstc 1 > IQ8X-80-M-US 25-79.5 V 43-60 V 320-540 Wstc 1 > So I'm good with three of the inverters on my list right? Not really. As the > solar cells age the degradation of the cell drops the cells voltage. A good > design practice is to drop the adjusted Vmp down 10% to make up for cell > degradation. So, 27.65 Adjusted Vmp - 10% would be 24.88Vmp. I would still > feel comfortable using one of the inverters on my list. > If I go to the Enphase compatibility calculator > <https://enphase.com/installers/microinverters/calculator> it shows seven > inverters that are compatible with the Phono PS400M6H-18/VHB solar module for > my climate. > > Other than that issue, we try to use micro inverters only when they are > reasonably easy to get to because we know we will be back at some point to > replace inverters. > Electronic components fail mostly based on temperature fluctuations over > time. The area behind a solar array is both the hottest and coldest location > at the installation site. I do like micro inverters for many applications > where there are multiple roof angles and or moving shade to deal with on a > client's roof. > > I would love to hear back from others if you think my calculations are way > off. This kind of back and forth is how we grow as installers and I won't > take offense if any of you slam my ideas. > > Thanks to all of you for contributing to our industry, > > Vince McClellan > President > NABCEP PV Professional > p: 541-485-8122 > a: 860 Conger St. Suite 12,. Eugene, OR 97402 > e: vi...@solarenergydesgin.com <mailto:vi...@solarenergydesgin.com> > w: SolarEnergyDesign.com > CCB# 161672 > > > If you have received this email and are not the intended recipient, please > delete this email. Copying or using any part, content, or attachment of this > email is strictly prohibited. > > > > On Tue, Sep 24, 2024 at 1:55 PM Jason Szumlanski via RE-wrenches > <re-wrenches@lists.re-wrenches.org > <mailto:re-wrenches@lists.re-wrenches.org>> wrote: > It's very curious how there are geographic preferences, and that is > definitely something to consider. I tell clients that there won't be anyone > to service their system 10 years down the line if they go with anyone but > Enphase around here. If a prospective client has 10 quotes locally, 9 of them > will be Enphase, and one will be Tesla. If they get an 11th quote they might > get a Franklin WH or another brand if they are doing battery backup. Even > SolarEdge is dead here, as far as I can tell. I haven't seen a competitive > quote with SolarEdge in ages. > > I can share this poignant advice with clients because I'm one of the only > people in Southwest Florida who will even touch something from Outback, > Scheneider/Xantrex/Trace, Sonnen, Magnum, SMA, or even old grid-tied Fronius > IGs. If someone wants to come and swap out HD Wave inverters as a living > here, I will gladly step aside. Swimming against the current gets very tiring > for consumers. Sometimes, you just have to follow the crowd. > > Jason Szumlanski > Principal Solar Designer | Florida Solar Design Group > NABCEP Certified Solar Professional (PVIP) > Florida State Certified Solar Contractor CVC56956 > Florida Certified Electrical Contractor EC13013208 > > > On Tue, Sep 24, 2024 at 4:41 PM August Goers <aug...@luminalt.com > <mailto:aug...@luminalt.com>> wrote: > I agree with Jason that it is going to take a really compelling microinverter > product at this point to knock Enphase off the #1 micro position. It seems > risky to sell any other microinverter products given the complexity of the > product and the fact that if the competing product manufacturer goes out of > business that there won't be any choice but to replace all of that product. > That said, competition in the market is good, so my salutes to anyone willing > to try other microinverter products. We have experience with SolarBridge > (they were owned by SunPower for a while) and that product was by far > inferior to Enphase. We've also installed a few hundred PowerOne ABB micros - > those have been for the most part very reliable, but the monitoring side of > the equation is very poor so dealing with RMA issues there is a bit of a > challenge. Both of those products are outdated now and no longer on the > market. > > I've posted here on this before - we're having good luck with the Tesla solar > inverter. It is low cost and has lots of benefits including 4 x trackers with > low start voltage, power control systems, built in monitoring, etc. We're now > offering Enphase systems as well (we were a SunPower dealer for many years) > so customers can have a choice if Tesla is not their cup of tea. Elon Musk is > aggravating. > > August > Luminalt > > > > On Tue, Sep 24, 2024 at 1:21 PM Jason Szumlanski via RE-wrenches > <re-wrenches@lists.re-wrenches.org > <mailto:re-wrenches@lists.re-wrenches.org>> wrote: > I don't really understand the resistance to Enphase on a roof (anymore, at > least). We have many thousands of microinverters out there, and I don't even > have a dedicated service department. We swap maybe 100 a year at the most at > this point, and that includes for systems we didn't install. It's super quick > and easy. But most of our roofs are single story 5:12 pitch on average. > > I have at least a dozen small commercial sites with 100 - 500 units each, and > I can't remembereven an handful of replacements on those over the years. > > I did get involved with a commercial site I did not install, and that was a > nightmare, with over 100 early generation microinverters that failed. It was > a custom rack, and the clamps were a nightmare, not to mention the array map > had gotten out of whack over the years from prior micro swaps. But for the > most part, I have no issue with micro swaps on roofs. > > Jason Szumlanski > Principal Solar Designer | Florida Solar Design Group > NABCEP Certified Solar Professional (PVIP) > Florida State Certified Solar Contractor CVC56956 > Florida Certified Electrical Contractor EC13013208 > > > On Tue, Sep 24, 2024 at 2:14 PM Dave Angelini Offgrid Solar via RE-wrenches > <re-wrenches@lists.re-wrenches.org > <mailto:re-wrenches@lists.re-wrenches.org>> wrote: > I am with Chris except I might put them on a barn roof ! Never a residence > and never Offgrid ! > > Dave Angelini Offgrid Solar > "we go where powerlines don't" > <http://members.sti.net/offgridsolar/>https://offgridsolar1.com/ > <https://offgridsolar1.com/> <http://members.sti.net/offgridsolar/> > e-mail offgridso...@sti.net <mailto:offgridso...@sti.net> > text 209 813 0060 > > > On 2024-09-24 10:16 am, Chris Schaefer via RE-wrenches wrote: > >> Was an Enphase installer since the beginning, I think 08' but moved away >> when the tech support and early model failures were numerous. Moved to APS >> with the two modules per micro. Really saved on install time as it was half >> the number of micro's. One recommendation regardless of brand, don't put >> them on a roof. >> >> Christopher >> >> On Tue, Sep 24, 2024 at 11:14 AM Bryan Norkunas via RE-wrenches >> <re-wrenches@lists.re-wrenches.org >> <mailto:re-wrenches@lists.re-wrenches.org>> wrote: >> I've had great luck with APS and so have our local installers. >> >> Bryan Norkunas >> PV-Cables Inc. >> 989 Milton Ave Ste 1D >> Ferndale CA 95536 >> (707) 923-3000 office >> www.pv-cables.com <http://www.pv-cables.com/> >> <Outlook-u2wnspqb.png> >> >> <Outlook-kadxvmqu.png> Please print only if necessary. >> >> NOTE: This email message and any attachments are for the sole use of the >> intended recipient(s) and may contain confidential and/or privileged >> information. Any unauthorized review, use, disclosure or distribution is >> prohibited. If you are not the intended recipient, please contact the sender >> by replying to this email, and destroy all copies of the original message. >> >> From: RE-wrenches <re-wrenches-boun...@lists.re-wrenches.org >> <mailto:re-wrenches-boun...@lists.re-wrenches.org>> on behalf of greg egan >> via RE-wrenches <re-wrenches@lists.re-wrenches.org >> <mailto:re-wrenches@lists.re-wrenches.org>> >> Sent: Monday, September 23, 2024 7:29 PM >> To: RE-wrenches@lists.re-wrenches.org >> <mailto:RE-wrenches@lists.re-wrenches.org> >> <RE-wrenches@lists.re-wrenches.org >> <mailto:RE-wrenches@lists.re-wrenches.org>> >> Cc: greg egan <g...@remotepowerinc.com <mailto:g...@remotepowerinc.com>> >> Subject: [RE-wrenches] favortie micro inverters? >> >> Esteemed wrenches, >> >> Have a client that is grid connected (not my usual client) and looking >> to do solar without back up. Has shading issues so I'm thinking micros >> would work best for this application, plus take care of rapid shut down >> without needing extra devices/wiring. Problem is I have not ever >> installed micros. >> >> Any recommendations on brands /models that have been reliable? Decent >> tech support? Customer just wants something that works and is >> relatively simple to navigate the online monitoring. Probably 4-5 kW so >> not a huge system. >> >> Thanks in advance, I appreciate it! >> >> Greg Egan >> Remote Power Inc. >> Fairbanks, AK >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> <http://re-wrenches.org/> >> >> List Address: RE-wrenches@lists.re-wrenches.org >> <mailto:RE-wrenches@lists.re-wrenches.org> >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> <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/ >> <https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/> >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org> >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> <http://www.re-wrenches.org/etiquette.htm> >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >> >> >> >> -- >> Chris Schaefer's >> <blocked.gif> >> Tel 585-229-2083 or Cell 585-748-1870 >> 5115 S Hill Road ~ Canandaigua New York 14424 >> www.solarandwindfx.com <http://www.solarandwindfx.com/> ~ E-mail: >> ch...@solarandwindfx.com <mailto:ch...@solarandwindfx.com> >> <blocked.gif> >> >> Thomas Jefferson, the author of our great Constitution, once said, >> "democracy" will cease to exist when you take away from those who are >> willing to work and give to those who would not." >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> <http://re-wrenches.org/> >> >> List Address: RE-wrenches@lists.re-wrenches.org >> <mailto:RE-wrenches@lists.re-wrenches.org> >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> >> >> There are two list archives for searching. 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