What if the owner is not home at the time?
William Miller Miller Solar.com 805-438-5600 www.millersolar.com On Tue, Jan 27, 2026 at 10:07 AM Dave Angelini Offgrid Solar via RE-wrenches <[email protected]> wrote: > The failsafe for me offgrid, is the owner has to know how to do these > things. I say bye bye if they are not capable. Sleep really well with the > independance concept. > > > > *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 [email protected] <[email protected]> > text 209 813 0060* > > > On 2026-01-27 9:14 am, Jason Szumlanski via RE-wrenches wrote: > > I don't like to install anything that isn't failsafe for this purpose, so > if it relies on a NC relay opening upon receiving generator voltage, I > usually won't consider it because the relay can fail. And if the > relay fails, there is no indication of that (other than the adverse effects > that might happen). > > That's just my opinion, but I can understand fringe scenarios where there > just isn't a way to get the solar connected on the line side. As long as > the customer signs off on the risks, I would do it, but cautiously. > > > 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 Mon, Jan 26, 2026 at 4:41 PM Howard Scot Arey via RE-wrenches < > [email protected]> wrote: > > Interesting. Somebody else recommended a web-based version of what you > did. You were ahead of the times. I might pursue this with the web > option...not the radios. Same concept - different technology. > > Thank you. > > *Howard "Scot" Arey* > *Owner, Solar CenTex* > > NABCEP PV Installation Professional > TECL 29755 > 254-300-1228 > > ------------------------------ > *From:* William Miller <[email protected]> > *Sent:* Monday, January 26, 2026 3:28:04 PM > *To:* RE-wrenches <[email protected]> > *Cc:* [email protected] <[email protected]> > *Subject:* RE: [RE-wrenches] Will IQ8 microinverters backfeed a generator > during grid interruptions > > Friends: > > > > I had the same problem: Enphase arrays on an outbuilding which was > connected to the generator side of a transfer switch. I had no independent > power path from the grid to the outbuilding so the Enphase had to be > connected to the load side of the transfer switch. When the large > generator was powering the facility and the sun was out the generator acted > wonky (unstable voltage). > > > > My solution was to buy a transceiver set (National Control Devices > MlrXR2x). I powered one radio from the grid side of the transfer switch > and the other radio controlled a contactor on the remote Enphase feeders. > When the grid goes down the contactor opens. > > > > The radios were inside of two buildings and the reception was borderline. > I augmented the included 900 mHz rubber duckies by replacing them with > panel antennas from Pasternak. So far the system is operating as intended. > > > > If anyone wants details let me know. > > > > William > > > > William Miller > > Miller Solar > > www.millersolar.com > > CA License C-10 77398 > > > > *From:* RE-wrenches [mailto:[email protected]] *On > Behalf Of *scot.arey--- via RE-wrenches > *Sent:* Wednesday, January 21, 2026 12:45 PM > *To:* RE-wrenches > *Cc:* [email protected] > *Subject:* Re: [RE-wrenches] Will IQ8 microinverters backfeed a generator > during grid interruptions > > > > Thanks but I'm just trying to grid-tie a small Enphase array without ESS > where the point of interconnection is on the customer side of the > generator/ATS. > > Trying to use existing wires in place to simplify and lower costs...but > the generator is my constraint because I need the PoI to be on line side of > the ATS. > > > > *Howard "Scot" Arey* > > *Owner, Solar CenTex* > > 254-300-1228 > > > ------------------------------ > > *From:* RE-wrenches <[email protected]> on behalf > of Jason Szumlanski via RE-wrenches <[email protected]> > *Sent:* Wednesday, January 21, 2026 2:33 PM > *To:* RE-wrenches <[email protected]> > *Cc:* Jason Szumlanski <[email protected]> > *Subject:* Re: [RE-wrenches] Will IQ8 microinverters backfeed a generator > during grid interruptions > > > > I should have also noted that Enphase DOES allow use of a generator with > its System Controller 3G, and supposedly the inverter, battery, and > generator sources can all power loads simultaneously, so I could be wrong > about how the IQ8s work. That said, Enphase has strict pairing > specifications and an approved generator list. They seem confident in their > ability to limit backfeed to the generator in this scenario. > > > > > 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 Wed, Jan 21, 2026 at 3:16 PM William Bryce via RE-wrenches < > [email protected]> wrote: > > If the AC coupled exported energy is more than the generator produced > energy, it can destroy the generator controller. > > That is why most AIO inverters have a relay on the dedicated AC coupling > input. It will open the relay if the inverter sees generator power. > > > > The MNP AIO will allow both inputs, but will open the relay if the AC > coupled power increases to 20% of the Generator input (firmware dependent). > > > > > > On Wed, Jan 21, 2026 at 2:27 PM Jason Szumlanski via RE-wrenches < > [email protected]> wrote: > > Enphase IQ8 microinverters will absolutely leak some power back to the > grid when set to a no-export grid profile. How much, and if that is > detrimental to the generator is another question. I suspect if the > generator is large enough relative to the PV array, the impact will be nil, > but I would not take the risk. > > > > I don't think the fast switching really does the trick in terms of not > exporting. That function relies on the consumption CTs connected to the > Gateway, which in turn communicates with the microinverters. Aside from the > CTs not being totally accurate, I don't see how that communication loop > could be fast enough. > > > > > 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 Wed, Jan 21, 2026 at 12:09 PM scot.arey--- via RE-wrenches < > [email protected]> wrote: > > Good day, > > > > I many years ago watched the fast-switching capabilities of the IQ-8 > microinverters to produce only what demanded of the MI, and wondered if it > might have application in a grid-tied system that is served by a > whole-house generator. > > > > We have the opportunity to install grid-tied-only array of 24 IQ8 but all > the MIs will be on the customer side of an auto-transfer switch and > generator. We want to leverage using existing building wiring to carry the > solar and all solar sizing meets the 120% rules. > > > > But I know that grid-tied solar on the customer load-side of the transfer > switch means no place for full solar power production to flow to when the > grid is not available...but then I thought back to that fast switching > capability: is there a way to ensure the IQ8 don't backfeed a generator > when it is operating for a grid anomaly? > > I suspect the answer is "are you nuts???" but that video of capability got > me thinking, "why not?" and if not, how is it - what tells the MI to cease > production? - when it is within a full and proper ISC/ESS system design? > > > > *Howard "Scot" Arey* > > *Owner, Solar CenTex* > > > > NABCEP PV Installation Professional > > TECL 29755 > > 254-300-1228 > > [image: cid:[email protected]] > > > > _______________________________________________ > 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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