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SMA Sunny Island SI6048 W331 Grid/generator disconnected

MurphyGuy

It just needs a bigger hammer
Joined
May 20, 2020
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This weekend, a major storm blew through Michigan and knocked out power to almost 200k people. We're still out as I type this.. What a joyous occasion! I got to activate my off-grid system in a real world test for the very first time..... and discovered a strange glitch I can't seem to figure out.

Every few hours, the Sunny Island SI6048 inverter will trip out and stop making power for about 3 seconds.. then reactivate again on their own. A review of the event codes shows the Master is throwing error code (W331 Grid/generator disconnected due to anti-islanding).

My system isn't connected to any grid or generator, it is a stand alone grid. All it does is take battery power, convert into 120/240 split phase (Master+Slave), and send it into the breaker panel through a double pole breaker on an interlock. The main breaker in the house's circuit breaker panel (150 amp) is off to isolate the house from the grid. There is no generator connected, no other inverters except the Slave unit. The only other source of power generation that is currently connected is the AC Coupled solar array which uses two Sunny Boy inverters.. and since its after midnight and very dark outside, I seriously doubt the panels are generating any energy.

The connection to my breaker panel is 4 wire. Hot-Hot-Neutral-Ground

Anyone have any clue?
 
Confirm your AC1 and AC2 wiring with us. What is going to what?
AC1 wiring is connected through a double pole interlock breaker to my home's main breaker panel. Main breaker to grid is off so the house is isolated except for the neutral/ground bus.

Nothing connected to AC2, the system is powered by battery juice and solar power only. The solar array (Sunny Boy SB6.0 inverters) are connected to the AC1 side through the home's main breaker panel on their own breaker.

I got to thinking this morning.. When I originally installed the grid tied array, I used a 70amp GFCI breaker and the Sunny Boy inverter kept tripping it out every night. Sometimes multiple times per night. It was fine during the day, but at night it would trip that breaker. Had to swap it out for a normal 70a breaker.

I actually have two Sunny Boy inverters now and I didn't put them into Island Mode until this morning. I'm wondering if the Sunny Island was behaving like that GFCI breaker.. Maybe those Sunny Boys do some kind of grid test in the middle of the night that GFCI circuits don't like.
 
I don't think the error code has anything directly to do with the Sunny Island inverter power dropout. I believe Island Mode works with Sunny Boy output control to modulate GT Sunny Boy's output power to match demand. Sunny Island controls the Sunny Boy output by changing its 60 Hz output frequency slightly. Further away from 60 Hz the more Sunny Boy power cuts back. Its only small freq spread around 60 Hz.

When there is no grid connection the power generated from Sunny Boy can only be consumed by Sunny Island battery charging or AC loads.

Check to see if batteries are fully charged when you have the dropout. You can also temporarily disconnect the AC coup[ing from GT Sunny Boy to see if Sunny Island drop out stops happening.

You didn't specifically say if drop outs only occcur during the day when Sunny Boy's are putting out power. If Sunny Island can't cut back Sunny Boy's power and battery charging or AC loads cannot consume created power the Sunny Island will shut down. If you have too much series resistance in battery path the Sunny Island may think battery is fully charged because DC input voltage will be higher then battery. You might play with charger voltage settings to see if you can make the problem better or worse with charge voltage setting.

Other possible reason is a moderate AC load being turned off causing a sudden situation of over production. Other issue is if battery AH capacity is not large enough to resist GT inverter grid presence testing.

GFI's trips when 120vac Hot and Neutral currents do not match indicating current is leaking out hot leg. Since the Sunny Island input relay is opened to main panel when grid is down I don't see that as a possible issue.
 
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I don't think the error code has anything directly to do with the Sunny Island inverter power dropout. I believe Island Mode works with Sunny Boy output control to modulate GT Sunny Boy's output power to match demand.

Check to see if batteries are fully charged when you have the dropout. You can also temporarily disconnect the AC coup[ing from GT Sunny Boy to see if Sunny Island drop out stops happening.

You didn't specifically say if drop outs only occcur during the day when Sunny Boy's are putting out power. If Sunny Island can't cut back Sunny Boy's power and battery charging or AC loads cannot consume created power the Sunny Island will shut down. If you have too much series resistance in battery path the Sunny Island may think battery is fully charged because DC input voltage will be higher then battery. You might play with charger voltage settings to see if you can make the problem better or worse with charge voltage setting.
This happened at night with bat SOC at 95%. I don't think I was clear with my explanation. It is the Sunny Island battery inverter that cut out for 3 seconds and threw the W331 (anti-islanding) error code. The Sunny Boy inverters were not making power because it was the middle of the night.

I'm going to wait and see how it goes today. So far, everything is fine. Lithium ion battery bank (25 kWh) is at 81% SOC, the sun is out, and the Sunny Island battery inverters are doing their thing. The array is currently making 4000 watts (out of 10.7kw) and we are running dishwasher and laundry while still pumping amps into the battery bank.

I'm interested to know if the Sunny Boy Grid Inverters will trip the Sunny Island battery inverter now that the Sunny Boy's are in off-grid islanding mode.
 
I understood it was the Sunny Island cutting out. Sunny Island should not even be testing the grid when grid is down as its input relay is opened. Since the firmware opens relay to grid when grid goes down it should know grid is down and no reason to test for it. It may just be bad wording on the alarm description.

Only other thing I can think of is a neighbor is backfeeding the grid from a generator causing the Sunny Island to temporarily believe the grid has shown up. I guess you could have the grid actually intermittantly coming on and dropping again but the Sunny Island should seamlessly handle that.

Sunny Boy's can trip the Sunny Island if its solar power is too much to handle either because of too much PV power or not enough battery size to resist the Sunny Boy grid testing (GT inverter tries to wiggle its output phasing). But not during the nightime.
 
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I understood it was the Sunny Island cutting out. Sunny Island should not even be testing the grid when grid is down as its input relay is opened. Since the firmware opens relay to grid when grid goes down it should know grid is down and no reason to test for it. It may just be bad wording on the alarm description.

Only other thing I can think of is a neighbor is backfeeding the grid from a generator causing the Sunny Island to temporarily believe the grid has shown up. I guess you could have the grid actually intermittantly coming on and dropping again but the Sunny Island should seamlessly handle that.

Sunny Boy's can trip the Sunny Island if its solar power is too much to handle either because of too much PV power or not enough battery size to resist the Sunny Boy grid testing (GT inverter tries to wiggle its output phasing). But not during the nightime.

The Sunny Island has no connection to the grid at all. It wouldn't matter if the grid was energized to 50 volts or 2000 volts, there is no conductive pathway to the grid lines.

My Sunny Boy grid tied inverters had a problem with the original GFCI breaker I had installed on the 4ga wire feeding them. It worked fine during the day, but sometime in the middle of the night, the GFCI breaker would trip open. Only happened at night, and it happened every night. The Sunny Boy inverters were configured for grid tie operation.

When I go into off-grid mode, I isolate the grid from the house and connect the Sunny Islands to the home's breaker panel through a double pole breaker on an interlock. (can't be turned on at the same time as the grid).

The Sunny Island battery inverters will start producing power, then the Sunny Boy grid tie inverters will see the mini-grid and also start to produce power. The next thing I do is to log into the Sunny Boy inverters and change them from Grid Mode to Island Mode.. but if the panels are not producing enough DC voltage, the inverters won't allow the change until the sun comes back up.

Next time we lose power, I'm going to either isolate the Sunny Boy inverters or get them changed over to island mode right away.. then see if the Sunny Island's trip out when the Sunny Boy's are in Island mode.

I think those Sunny Boy's do some kind of arc fault or neutral test in the middle of the night and its causing problems.
 
Sunny Boy's can trip the Sunny Island if its solar power is too much to handle either because of too much PV power or not enough battery size to resist the Sunny Boy grid testing (GT inverter tries to wiggle its output phasing). But not during the nightime.

I forgot to address this part.

The Sunny Islands are hooked to a 25kWh lithium battery bank and will throttle the Sunny Boy grid inverters when needed. The Sunny Island battery inverters use a technique called "Frequency Shift Power Control" that will force the Sunny Boy grid inverters to throttle down if we don't need the energy. This happens all the time when the battery bank is near full and the solar array is under full sun. The Sunny Islands will raise the frequency to between 61 and 62 hz and the grid inverters will throttle down proportionately. Its actually pretty cool to watch it happen.
 
For Sunny Island to say "anti islanding" it has to think it is on grid. Maybe a different quick-start configuration would fix that. But without it ever see power on its AC input it shouldn't ever close those relays. You don't have AC1 and AC2 connected together, do you? (people have done that.)

What is supposed to keep the battery charged? With AC input disconnected and Sunny Boys on your main panel, no charging source.
Only when you flip interlocked breakers and connect AC output to main panel are Sunny Boys available to charge it.

You switch Sunny Boy manually to off-grid under those conditions? If you forget to switch back to UL1741 when flipping interlocked breakers back to utility, you have a on-UL1741 inverter connected to the grid, which is bad.

What I did was I had a breaker from main panel to Sunny Island input. Output of Sunny Island goes to PV breaker panel with Sunny Boys. Also goes to interlocked "generator" breaker in main panel. During blackout, switch off breaker feeding Sunny Island. Flip interlocked breakers. Then I have house and Sunny Boys on output of Sunny Island.
 
For Sunny Island to say "anti islanding" it has to think it is on grid. Maybe a different quick-start configuration would fix that. But without it ever see power on its AC input it shouldn't ever close those relays. You don't have AC1 and AC2 connected together, do you? (people have done that.)

What is supposed to keep the battery charged? With AC input disconnected and Sunny Boys on your main panel, no charging source.
Only when you flip interlocked breakers and connect AC output to main panel are Sunny Boys available to charge it.

You switch Sunny Boy manually to off-grid under those conditions? If you forget to switch back to UL1741 when flipping interlocked breakers back to utility, you have a on-UL1741 inverter connected to the grid, which is bad.

What I did was I had a breaker from main panel to Sunny Island input. Output of Sunny Island goes to PV breaker panel with Sunny Boys. Also goes to interlocked "generator" breaker in main panel. During blackout, switch off breaker feeding Sunny Island. Flip interlocked breakers. Then I have house and Sunny Boys on output of Sunny Island.

AC1 and AC2 are not connected together.

The solar array on the AC1 side is the only power source to keep the battery charged. The AC2 terminals are wired to a 50 amp 4-wire receptacle and I can hook either the grid or a generator to that receptacle if I need to do some kind of emergency charging. I have a special 6ga patch cord that is used for the AC2 side only. That patch cord is not currently connected.

Yes, I do a manual switch over from UL1741 to Island Mode within the Sunny Boy Grid Tied inverter's user interface. We have a checklist for activating and deactivating our off-grid operations. The check list is step by step instructions with pictures as well as a quick reference check list, and everything is clearly labeled for proper identification.

It really isn't that complicated.. Turn off the main breaker, lift up the off-grid (generator) interlock plate, turn on the off-grid breaker and activate the Sunny Islands. There's a bit more to it than that.. the main battery breaker has to be turned on and the BMS has to be turned on.. but its very easy to do. The system is well organized and constructed. I'll attach a couple photos.

The Sunny Boy inverters do not have to be changed over to Island Mode, but the system operates more gracefully when it is.

As for battery maintenance, the lithium batteries do not self-discharge much. They might loose 0.5% of their charge over 6 months and we lose power far more often than that. I was keeping them at 3.5 volts for storage, but have since raised that to 3.75.

We keep the system completely isolated when not in use. There is no conductive path from the off-grid battery system to anything. If we want to use it, we plug in 6ga 4-wire patch cords. I'm not risking $10,000 worth of hardware on the chance than an EMP, voltage spike, or a lightening strike won't come down the Neutral line.
 

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True, completely isolated is better protection. So long as nothing sparks across the gap of the interlocked breaker.
I suppose you could install an L1/L2/N short as additional protection rather than increasing the airgap.

And as you say lithium has low discharge rate and doesn't mind being kept less than full. I could do that with my AGM, charge every 6 months.

I installed larger MOV surge arrestors on input to Sunny Island. My grid connection is underground from an underground transformer. A lightning strike has to jump to secondary before it would reach me.

I wanted brownout protection for my equipment, so using Sunny Island as UPS provides that.

Your lithium would tolerate repeated cycling better than my AGM, but it is much nicer to have frequency-shift working. "backup" didn't work correctly for 10000TLUS and SMA said set to "island" or "off-grid". I'll be changing the Sunny Boys to 5000US.

Are your Sunny Boys easy to reconfigure? I have to connect by Speedwire and use Sunny Explorer. If I was using RS-485 that would be a real pain because I have to open cover and swap daughter board, but I can just leave the one board installed.

I've since added load-shed relay for house loads on Sunny Island. Garage loads are straight to grid, use the interlocked breakers.

Still funny that your Sunny Island "disconnects due to islanding". Even if that happens it should still be making output, but I guess with that failure it shuts off for a bit? How is it configured?

"Value in variable Explanation
PvOnly Stand-alone grid, no utility grid, no generator
Gen Stand-alone grid with generator
Grid Battery-backup grid
GenGrid Battery-backup grid with generator"

I would think "Gen", stand-alone (island) grid with option to charge from generator.

Wonder if the AC2 side is floating, coupled with enough signal it thinks voltage is present and connects? If the input was grounded not floating, should ensure no voltage can be seen. Maybe grounded by plugging your power cord into a box with a couple lightbulbs, so if Sunny Island does something stupid like closing the relay, it won't see a dead short.
 
Our interlock breaker leads to nothing but a large 4-wire receptacle. A lightening strike would have to jump about 30 feet to reach my off-grid system.. and if that happens, something tells me the expensive battery and electronics aren't going to be much of a concern anyhow as my home burns to the ground.. LOL

You're using AGM for off grid storage? Why? Except for maintenance issues and some fumes, flooded batteries will outlast any AGM. I use an AGM deep cycle for my office computer's UPS.. I have a dinky little APC Smart UPS that had a 7 minute battery pack so I converted it to something a little more substantial. Now I have 2.5 hours. Beyond the major storms three or four times a year, the grid power out here likes to flake out for 10 to 20 seconds at a time almost twice a month. Not a big deal, but the computers don't like it at all.

If you look at the photo of my off-grid system, that gray junction box below the Sunny Island has a load shedding relay in it. I picked up an ABB relay on Ebay ($25) with a 48vdc dual stage coil that only draws 2.4 watts to stay engaged and is rated for 160 amps. When it energizes, it sounds like someone slamming a 400 page hardcover book onto a table.. You can hear it throughout the entire house..

Sunny Boys are extremely easy to configure using a standard web browser as they operate just like a website. I also use Sunny Explorer when I want to monitor overall system performance. The Sunny Explorer software is a bit clunky and glitchy, but it allows me to see the combined data for both of the Sunny Boy inverters.. all power graphs can be seen individually or combined. But if you just have a single inverter, the inverter's own web based interface works just fine.
SMA is not known for their user interfaces.. Like some kind of cosmic joke, the better the hardware, the crappier the user interface. How does one design the best damn off-grid inverter in the world, and then put a 2 line dot matrix display on it?

You can plug in an ethernet cable right into the Sunny Boy SB series.. and if you have more than one inverter like me, you can daisy chain the inverters as they each have two ethernet ports that act like ethernet switches.. You'll even see two different IP addresses.

There is NO communication line between my Sunny Islands and Sunny Boys.. there doesn't need to be any as the Sunny Boys react to the the frequency shift all on their own. Even in grid tied mode, they will just shut down at 62hz.. Not so graceful, but it would work. This is why I get the off-grid system working first, then go to the office and change over the Sunny Boy's to island mode..

The W331 error has happened once and it reset itself and the power came back on before I was even able to lift my rear end off the chair.. Power was out for like 2.5 seconds. Came back on before I could even react to it.

I like your idea of the AC2 contacts floating, however, from page 48 of the manual:
No all-pole isolator on the Sunny Island
The Sunny Island is not equipped with an all-pole isolator. The neutral conductor (N conductor)
is looped through the device and the N terminals of AC1 and AC2 are connected inside the
Sunny Island.


The above statement would seem to indicate that one only needs to connect the Neutral from either side for it to work on both AC1 and AC2. Damn good idea.. but that's not it.

I have it configured for GEN ONLY. I started off with GRID GEN but since I never hooked up the DigIn contacts, I just switched to GEN ONLY mode so it wouldn't flake out due to the portable generator's sloppy power. I set it to draw 15 amps from the generator for charging. This puts the generator at about 70% load.
If I ever get that W331 error again, I might change to PV Only mode to see how it behaves.
 
OK, so you have a "generator cable" from Sunny island to the breaker panel. That certainly isolates it.
While unplugged, if you operate Sunny Island stand-alone it will have floating neutral. I plan to have a socket with neutral and ground shorted together I can plug that cable into (another setup, to be mobile on a truck.)

MY Sunny Island setup is grid-backup, not off-grid, so I'm not cycling nightly - only during blackouts. So limited cycle life of AGM is OK. My battery bank is 20 kWh, 14 kWh useable, barely enough for one night if I turn off unnecessary loads. If I also shed 1990's era refrigerators at night could be much smaller. I paid extra for batteries with zero maintenance.

Same neutral on AC1 & AC2. I only hooked up one, due to my conduit configuration.
It's not the neutral I'm suggesting might cause the islanding, but the hot wire. I only ever see 50% of voltage when wires in a conduit are coupled, but I'm sure I could lay wires to maximize coupling. So I was suggesting shorting/biasing the incoming hots to neutral to ensure nothing can couple them high.

I bought a used relay with dual coil, but it had bad contacts. Then I bought the SMA one (ABB, I think) from a vendor in Europe. 10 ohms, 5 amps, 250 watts drawn from an 0.5A PTC fuse in Sunny Island. But it closes and changed coil resistance fast enough to not trip.

My older Sunny Boys don't have the newfangled PC communication interfaces, but they do have RS-485 cards. My Sunny Boy Control talks to some Sunny Boys but not others, and doesn't talk to Sunny Island. I recently acquired a Web Box so will try that (but not connect it to the internet.)
 
Yes, floating neutral if operated stand alone, but we don't do that because its not very useful. We just plug it into the home's breaker panel and fire it up.

I wish I had purchased more cells than I did. My bank is made of 56 cells that were destined for the Chevy BOLT EV. They were brand new and never cycled and I paid $80 per kWh for them shipped to my door. If I had known then what I know now, I would have bought 200 of them.

I would be very interested in seeing the Web Box interface. I hate the fact that I don't have a complete picture of my energy usage. Its becoming an obsession with me. I'm considering purchasing a brultech unit to monitor all the energy in the house.

Unfortunately, our power came back on today mid-afternoon. I guess that's an attitude not many people experience.. lol. So we're back on the grid and I left the Sunny Islands turned on so they bleed away some energy from the battery bank just sitting there idling. Its sitting at 3.9v per cell right now and I need to get that down to 3.75. Probably going to take a couple days, might have to plug in a space heater to it or something.
 
UPDATE:

So as I said earlier, the grid came back and we switched over to it. I disconnected the off-grid system but left the sunny island inverters active so they bleed off power from the battery bank. Bat voltage at 3.9 per cell and I need it to come down to 3.7. The Sunny Islands pull 25w each so two or three days should get me pretty close.

I disconnected the patch cord as well, so the off-grid system isn't connected to anything. No hot wires, no neutrals, not even a ground..

And it just did it again. I heard the load shedding contactor kick out and re-engage about two seconds later. So its not the solar array grid inverters doing it.. the problem is internal to the sunny island inverters themselves.
 
any other errors before W331? And does your BMS talk at all to the 6048?
No other errors but the BMS does talk to the Sunny Island.. the BMS controls and monitors all Sunny Island charging functions.

Its not the BMS though. The BMS also controls a kilovac contactor that will open in the event of a problem and it would let me know there's an error, and that's not happening.
 
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