[RE-wrenches] All-In-Ones / Sol-Ark fail

[Jason Szumlanski]

I absolutely have a 400A bypass switch here. In fact, there is also a 200A
DPDT switch that allows you to select between two generators!

If someone was able to be there during or after the storm, we could have
gotten the power back on, for sure. I think the inverters would even pass
through power without flipping the switch. I was apprehensive to use the
Gen Force function remotely with nobody there, especially because I might
not be able to turn it off if connectivity is lost.

Tomorrow will probably be our earliest possibility of getting out there,
but there is a lot of debris in the water, so it's risky.

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 Thu, Oct 10, 2024 at 5:35 PM Dave Tedeyan via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Yikes! I cannot speak to the AIO's in general.
> However, I do still always install some sort of inverter bypass in battery
> based systems. Then in case of a failure like this you can at least
> continue to power the house off the generator as long as someone is there
> to throw the switch.
>
> Cheers,
> Dave
>
> On Thu, Oct 10, 2024, 4:58 PM Jason Szumlanski via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> We have been talking a lot recently about all-in-ones. I just had a
>> massive fail during Hurricane Milton with a quad Sol-Ark 15K off-grid
>> system that deserves some discussion about whether AIO is a good idea if it
>> can't build in some resilience to errors. I'm not sure if the new Midnite
>> unit is better in this respect, but this is what happened to the Sol-Ark
>> system...
>>
>> Four inverters, each with 4 strings of PV paralleled to 2 MPPT per
>> inverter. One of the slave units developed some sort of PV DC fault during
>> the storm. This caused the slave inverter to shut down and throw an error,
>> which in turn caused a parallel fault across all four inverters. Power
>> output ceases at that point. Apparently the system keeps resetting because
>> I have a cell modem that uploads data to Sol-Ark, but that cell modem is
>> powered by the inverter outputs, so it must be getting power at least
>> intermittently. The rest of the loads are basically flatlined according to
>> the Sol-Ark data. It's mostly air conditioners, so they probably can't turn
>> on fast enough before the PV fault causes another shutdown.
>>
>> So, in essence, one of 16 strings of PV develops a fault, and that causes
>> all four inverters to malfunction? What is the point of redundancy if a
>> fault of one results in a fault of all?! If there is a true PV input fault,
>> shouldn't that just shut down that MPPT, or perhaps all of the PV DC input
>> to that inverter? And why can't this inverter continue to invert power from
>> the batteries and charge from a generator when there is a DC input fault
>> that could be programmatically isolated and ignored?
>>
>> This is a bad design in my opinion, and something I hadn't considered. If
>> the faulted inverter can't function with a DC input fault, it should just
>> take itself out of the game. (This is 120/240 split phase, BTW). Is this
>> how all AIO inverters work? One inverter fault on the DC side kills all
>> paralleled units' AC output? Not good.
>>
>> This is a completely off-grid system on a remote island with no vehicle
>> access, so it's not exactly easy to do a "truck roll" on this one,
>> especially post-hurricane. To make matters worse, the generator was running
>> at the time of the fault, as it was being signaled to run because the
>> battery had reached the assigned charge voltage. The fault also killed the
>> 2-wire start signal from the master, so the system also stopped passing
>> through generator power to the loads. The house is dark.
>>
>>
>> Jason Szumlanski
>> Florida Solar Design Group
>>
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