Another reason to do separate charge controllers is Low battery. If the
AIO inverter hits its LBCO, then it takes out the PV input as well. Then
the draw of the BCM takes what's left in the battery, and you're into a
dark start. Generator won't even help. AIOs are easy to install, but
not as full proof as DC coupled PV systems. Also, the inter
communication is a major issue. I've seen inter connected charge
controllers take each other out, which really defeats the redundancy of
having multiple units. I'm sure many on the list will question my
wisdom; but I usually don't interconnect any of the equipment from a
comms stand point. I use open loop charging based on voltage.
I once had a pinched temp sensor, that thought the batteries were at
5000 deg Kelvin. It shut all 4 inverters down. My most reliable
multiple inverter setup is a four SW4048 system that is now 24 years
old. Each inverter feeds one leg of two load centers. No comms, No 240
vac loads. No shut downs. That is the gold standard, and none of the
AIO stuff, nor the module level rapid shutdown etc, can even get close
to the level of reliability we had in the past. In the off grid world,
shut downs can be life threatening, and all the additional "safety"
stuff added to the code since, has actually made my off grid customers
less safe.
You have to think what happens if the battery gets low, and no one is
home? Can it recover on its own, like a traditional DC coupled Lead
acid system? Basically, If the system can't hit LBCO, recharge the next
day, and automatically turn loads back on, we've gone backwards in our
designs, and equipment selection. AIOs are inferior if they can't
achieve this basic functionality. If UL standards are causing this,
then those standards are incorrect for critical off grid and backup
applications.
Ray Walters
Remote Solar
On 10/10/2024 4:02 PM, Eric Smiley via RE-wrenches wrote:
Install stand-alone charge controllers. That is the only way to get
redundancy.
Eric Smiley (he/him) - Design Manager
250.703.6004
[email protected]
888.386.0116
3-4997 Polkey Rd, Duncan BC, V9L 6W3
viridiansolar.ca
<https://www.google.com/url?q=https://viridiansolar.ca&source=gmail-html&ust=1702155901939000&usg=AOvVaw3SHpXB-WRSlzWmjpz4htqG>
Viridian Solar honours the ancestral grounds on which we live and
provide services, recognising that these lands are unceded Indigenous
territory. We are steadfast in our commitment to reconciliation and
acknowledge the rich history and traditions that characterise this
land that we all consider home.
On Thu, 10 Oct 2024 at 14:59, Lou Russo via RE-wrenches
<[email protected]> wrote:
Aloha All,
Thank you Jason. This is a huge and surprising issue. So much so
that I dropped what I was doing and called Sol-Ark to confirm.
Mind you this was level 1 support, but I was told this is what the
Sol-Arks are supposed to do and it is a feature not a bug.
Their take is if there is any fault on any one string, the Sol-Ark
assumes the worst and shuts everything down.
I wonder what solutions could be implemented on future installs to
prevent this from happening?
Aloha,
Lou Russo
Owner
[email protected]
Office - 808 345 6762
Spree Solar Systems LLC
CT-34322
On Thu, Oct 10, 2024 at 11:45 AM Jason Szumlanski via RE-wrenches
<[email protected]> wrote:
I think it's more likely water in a J-box or possibly physical
damage, but someone passed by the property and did not observe
any physical damage to the array.
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 5:41 PM Jay <[email protected]> wrote:
Jason
What’s the possibllity it was a lighting strike?
Jay
On Oct 10, 2024, at 2:57 PM, Jason Szumlanski via
RE-wrenches <[email protected]> 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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