| Jason
Which fault are you getting?
This spring I was getting F23-Tz_GFCLO randomly on an upper roof array.
After further investigation, I found several modules with broken glass. After replacing the mods, all is well.
Thank you,
Maverick
Maverick Brown
Off-Grid Solar Commander since 2006
Maverick Solar Enterprises, Inc.
• Solar Commander Remote Power
• SunFlow Systems Cathodic Protection
maver...@mavericksolar.com
512-460-9825
On Oct 11, 2024, at 1:39 PM, Jason Szumlanski via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote:
By shutting off the PV disconnects on the two affected inverters we were able to make the system work successfully today. As I mentioned, we will dig into the actual faults on Monday. From the historical data, I found that this issue has actually been going on for a week before the faults started happening in the inverters. I'm not sure why the faults took so long to cause a shutdown of the inverters. Maybe it just "got worse" and finally triggered a fault. The first faults would have been during the early band of rain from Hurricane Milton, so possibly water or wind put the issue over the top.
Before the shutdown, each of the two affected inverters had one MPPT with voltages out of the expected range for the last week.
All MPPT strings are 14 modules with 7 in series, 2 in parallel. Each string Voc is 342V and Vmp is 297V.
On the first affected inverter, I was able to observe the bad string operating consistently around 370V to 400V+, which is obviously well above the Voc (and it's hot here in Florida). The good string on this inverter operated around 260-270V during the same time, which is the expected range.
On the second affected inverter, I observed the bad string operating consistently around 100V to 130V+. The good string on this inverter operated around 260-270V during the same time, which again is the expected range.
Graphs are attached for those of you who like that kind of stuff. These show a typical day after the issue started to occur, but before the inverter faults occurred.
Incidentally, the average voltage of the two bad strings seems to be pretty close to the normal strings, so that is a good clue. 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 ![]() More interesting information... When the sun went down last night, the fault cleared and the inverters started producing power again, drawing from the batteries, and restarting the generator. The master inverter "remembered" the generator was in it's charging cycle and hadn't reached full battery yet.
It's good that the inverters started inverting again. That's a plus. I actually wish the generator hadn't started because it was unnecessary based on battery voltage, which was near full anyway.
Which brings me to another annoying behavior of the Sol-Arks that I discovered in how the GEN Charge and GRID Charge parameters work with signaling the two-wire start. If the battery voltage is 50V and the charge parameter is set to 49V, the generator signal will not kick on of course – the generator start relay is open. However, if you change the charge parameter setpoint to, say 51V, the generator should start because the battery voltage is below the setpoint. But that does not happen. The battery voltage must "fall through" the parameter setting for the charging to be triggered and the relay to close. If you are in a situation where you need to get the generator on a charge cycle and then leave the site, the only way I have found to do this is to set it to something very close to the battery voltage, say 49.9V, put a heavy load on to drop the voltage below the setpoint, let the generator start, then change the setpoint to the desired 51V.
Back to the original issue – I dug into the string voltage data history remotely and narrowed down the fault to two of the four inverters. I am sending someone to shut down the PV DC switches on these two inverters today in hopes that we can keep the power flowing during the day and through the weekend. I'm planning on a Monday boat ride out there to see what caused the fault(s). I will report back. 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 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 Office - 808 345 6762 Spree Solar Systems LLC CT-34322
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 Jason What’s the possibllity it was a lighting strike?
Jay 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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