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"
[2]https://offgridsolar1.com/ [3] [2]
e-mail [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 [1]
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
_______________________________________________
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. 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
_______________________________________________
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. 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
_______________________________________________
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. 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
_______________________________________________
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. 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
_______________________________________________
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. 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
Links:
------
[1] http://www.millersolar.com/
[2] http://members.sti.net/offgridsolar/
[3] https://offgridsolar1.com/
_______________________________________________
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. 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
