[RE-wrenches] Dual radian system stopping selling on sunny days

Fri Sep 26 15:19:52 PDT 2025

It is interesting that a couple people mention the FNDC. It seems that
completing the charge parameters sets off the issue. I am also toying with
lowering the end amps or something like that so that it is less likely that
the system would ever get to a full charge. Although, I realize that may
end up overcharging the batteries when the grid is down...

I did finally get a hold of someone from Outback who suggested updating the
firmware on the Mate3. If that does not work then I'll have to somehow
coordinate to be there at a time that the problem is occuring and also
schedule a call from Outback at the same time.

Disconnecting the FNDC or a factory reset are also good ideas.

Cheers,
Dave

On Fri, Sep 26, 2025, 5:38 PM Jay via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> I have a few out there all offgrid, so this particular issue I e not seen
>
> But I have had all sorts of weird issues that occurred long after any
> changes to the system. AGS was a big one.
> After I double checked all the settings I usually resorted to a full
> factory reboot of everything.
>
> And that usually fixed it.
>
> Good luck
>
> Jay
>
>
>
> On Sep 26, 2025, at 3:26 PM, scot.arey--- via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> 
> I don't have but two paralleled Radian systems but I removed the FNDC in
> those. While I REALLY want to love and use the FNDC, I feel like that gives
> unintended issues in more complex systems.
>
> *Howard "Scot" Arey*
> *Owner, Solar CenTex*
> 254-300-1228
>
> ------------------------------
> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on behalf
> of Steve Higgins via RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Sent:* Friday, September 26, 2025 4:01 PM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Cc:* Steve Higgins <steve at surrette.com>
> *Subject:* Re: [RE-wrenches] Dual radian system stopping selling on sunny
> days
>
> Dave,  I've had the same thing happen with a couple of systems...
>
> Do you have the FNDC installed?
>
> Outback wont admit it but I think that there is a software conflict
> between the FNDC and the radian firmware.
>
> The only way I could get it to stay in sell mode was to remove the FNDC.
>
> *Steve Higgins* *⋅* *Technical Services Manager*
> *t* +1.902.597.4020   *m* +1.206.790.5840
> *f* +1.902.597.8447   *e* steve at surrette.com
> ------------------------------
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> On Fri, Sep 26, 2025, 10:53 AM Dave Tedeyan via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> To the Outback extraordinaires,
>
> I've got a dual radian, grid tied system that has been in service for
> about 9 years. Recently, it has started this behavior where it will stop
> selling to the grid on sunny days. Looking back at the data, this has
> happened intermittently and very infrequently a couple years ago. But now
> we are at the point where it happens every sunny day. Once the batteries
> get up to fully 100% charged (not 99%), the selling stops and the system
> only harvests enough solar to cover the backed up loads.
>
> I got a hold of the USB card data. It appears that the inverter goes from
> "Sell Enabled" to "Offset" when this happens. I cannot tell whether the
> inverter randomly decides to switch mode and then stop selling, or whether
> it is the stopping selling that puts it in "Offset" mode. The sell voltage
> is set at 52V, and float is set to 54.4V. It looks like the batteries are
> generally sitting around 54V when this happens. Once the inverter enters
> "offset" mode, then the battery voltage stays steady at 54.0V
>
> Does anyone have any idea what can be causing this to happen?
> Cheers,
> Dave
>
> --
>
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