[RE-wrenches] Enphase excess solar for IQ system controller

Wed Sep 25 14:15:01 PDT 2024

With IQ8 series microinverters, there is an absolute limit of 64A connected
to the IQ Combiner input lugs of the System Controller. The DER port is not
for PV. It is for batteries that exceed the limits of the storage port. You
can have up to (8) 5P on the Storage lugs and (8) on the DER lugs. But
these will be power limited to the output of (4) 5P batteries per input. In
other words, this is a way to connect 80kWh of capacity to the system, but
you will only have 128A of power output even though the (16) batteries are
capable of 256A. Anyway, 64A is the PV limit for backup systems, and there
is no way around it with IQ8.

You CANNOT connect any additional IQ8 microinverters on the load side of
the System Controller when there is backup involved. All IQ8 must be
connected to the IQ Combiner lugs on the System Controller. The relay in
the system controller must be able to turn off the IQ8 micros. This relay
also disconnects the rooftop micros when the RSD switch is turned off.

The additional microinverters can be connected to the line side of the
System Controller (as a feeder tap or anywhere upstream of the System
Controller that complies with code). You do need a separate IQ Gateway,
because these microinverters need to be configured for grid-tie only. All
microinverters connected to the same Gateway must have the same mode. The
micros connected to the backup system will be set up as multi-mode.

Don't bother with a line filter unless it becomes truly necessary. There
are things that Enphase can do on its end to reduce the crosstalk by
establishing separate domains. They SAY you need a line filter, but this is
rarely the case. Don't listen to anything that Tier 1 customer service
tells you regarding powerline communications. That's their go-to response
when they can't figure something out.

As for the Sunlight Backup system, I don't have a single client that is
satisfied with this setup. It really needs at least one IQ Battery 5P to be
functional, in which case you can forget about the ridiculous limitations
of 8 x 120V or 4 x 240V circuits and the rigmarole of two load controllers
that Sunlight Backup requires, especially with that much PV. I would avoid
Sunlight Backup at all costs. It's not useful for anything but the smallest
loads during the best conditions

As for your crosstalk issues, here is what I would do. Have customer
service retire one of the IQ Gateways and all associated microinverters.
Provision the other IQ Gateway and get those microinverters working. Then
turn OFF power to the working Gateway and microinverters. Turn ON power to
the other Gateway and microinverters and have customer service unretire
everything. Reprovision using ITK. Once everything is working on the second
Gateway, turn the first one back on and all microinverters, and you will
probably be up and running without further issues.

I was really disappointed with the discontinuation of the IQ7 because of
this 64A hard limit of PV on a backup system. With IQ7 you could have 96A
of PV with the previous generation battery. The IQ8 was a step backward for
large backup systems. I provided this feedback to Enphase, and they were
working on a possible workaround to make something work, but I would not
hold your breath. I even wrote this article when the issue first came to
light:

https://floridasolardesigngroup.com/enphase-iq7-versus-iq8-microinverters/

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, Sep 25, 2024 at 3:02 PM Dave Tedeyan via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hi all,
>
> All this talk about Enphase recently and I have a design question that I
> am having trouble getting a straightforward answer to. The IQ system
> controller can take up to 64A of PV AC output on the DER port (coming from
> the IQ combiner for example). When there is more solar on site, the
> question is what do you need to do with the rest of the solar.
>
> They have a system planning guide that talks about some of this and you
> can find it here:
> https://enphase.com/download/planning-enphase-energy-system-tech-brief
>
> Page 59 bullet point 6 says that with IQ8 micros, the excess PV must be
> split into a grid-tied system. I recently did this, got a separate IQ
> gateway, and a power line filter, and the system continues to have cross
> talk issues between the two gateways, and the microinverters will just not
> report properly no matter how many times tech support re-provisions the
> devices and prevents each gateway from looking for more devices.
>
> Then I noticed that with M series micros (page 62 bullet point 9) it says
> that microinverters exceeding 64A can be added to the main panel. In this
> scenario, there will be more than 64A of solar flowing through the IQ
> system controller, even though the DER port is limited to 64A. I would like
> to do something similar to this for my system with crosstalk issues and get
> rid of the second IQ Gateway.
>
> I asked tech support why there was a difference in the planning document
> for IQ8 and for M series and whether I could add the extra IQ8 into the
> backed up subpanel (This is a Sunlight backup system). They did not give me
> a fully complete answer, but they did say this, "You can add the panels up
> to 64A into the system controller and exceeding PV can be connected to the
> backup subpanel."
>
> I fear that this was a level 1 tech and that they may not have completely
> understood the situation. This is the answer that I wanted, but I am not
> sure I trust it yet. Has anyone here tried something similar to this?
>
> Thanks!
> -Dave
>
> --
>
> [image: Logo] <https://www.sungineersolar.com/>
> Dave Tedeyan, P.E.
> Owner | Sungineer Solar
> p: he | him | his
> a: 1653 Slaterville Rd. | Ithaca, NY 14850
> w: www.sungineersolar.com <http://www.sungineersolar.com/>
> c: (607) 270-0370
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