Tech Support: Four SP6548 inverter settings

[garetwo]

Electrician with negligible knowledge of PV systems…for now.

Online documentation. https://drive.google.com/file/d/1FAa6VnEkGG1d4d6sBfqJ82VOCE5lMgB6/view?usp=drive_link

There were two SunGold Power older model SP6548 each providing 120VAC, together providing 240VAC to a small loadcenter. Power was from a 6kw solar array and twelve batteries.

SunGold said we should not run the small (under 10k) generator directly to the Gen/Utility inputs because the built-in charger would have a hard time with the supplied power. SunGold implied using a 15kw generator would be better, but there are threads in this forum where smaller generators are used by tweaking the frequency and setting the charger output to low amps.

So, the inverter AC inputs were connected to utility via 60-amp breakers. AND the generator was used to manually charge the batteries through a pure sine wave inverter. The client would turn the utility feed to the inverters off, forcing solar/battery usage, then manually charge the batteries as they ran low.

The system is now four SB6548 inverters (two each 2P1 and two each 2P2 180 degree) and 16 batteries – 4 banks of 4 in series. I am confused with 4S4P versus 4P4S, so please do not ask me (yet). The batteries are JITA LifePO4 12.8Vdc 300Ah.

I messed up the initial step, from two inverters to four, by taking the output power from the first two 180 degrees out inverters and connecting them to the same phase via breakers. So, when the breakers were engaged, they immediately tripped. I figured I was about to buy inverters. But, after correcting my mistake, the units seemed to function.

When I got home, the client told me they lost power, or more accurately, things were not working – like the garage door opener sounded weird and only opened a few inches. There seems to be an issue with loads not getting proper voltage SOMETIMES. I have not been there when this happens, so I have not been able to measure anything. We need to figure out how to download the error logs.

I know I need to try and cause the failure so I may see better what is going on. But, for now, I am asking for thoughts on the problem as well as how to properly set up the inverters. All four inverters are online, all sixteen batteries are connected, but I do not understand all the settings. I am asking for help with respect to:

12 – is 44VDC safe?

How does this impact 29 LOW DC CUTOFF VOLTAGE?

13 – what is lowest this may be set at?

26 – What is bulk charging mode?

What does it do?

27 – What is floating charging voltage?

What does it do?

29 – Should this value be less than 12 VOTAGE BACK TO UTILITY?

30-36 – Should we use equalization?

41 – Should this stay disabled?

 

[garetwo]

I have received a lot of input in a battery section of this forum as well as from SunGold itself. In the interim, the client had all four inverters fail with a fault 86. The inverters had been online for a few days and no adjustments had been made to setting 28. I post this here merely to keep track of what is going on and to find out what needs adjusting. I do not think the PV array in place canNOT charge all of these batteries completely, especially this time of year. Do I have this question in the wrong forum? That is something I would do.

 

[Skypower]

What are you settings (28) for each inverter? After you’ve set them did you cycle them off to see if the settings kept? Was each inverter actually contributing to load or could one just have been in limbo because the setting hadn’t taken?


I think it’s unlikely at this point because it was working, but you may have a different firmware between the new and older inverters. Use the up/down button to display the U1 and U2 versions on each inverter. I don’t know which versions are compatible or if it’s even the issue. If it is the issue it should be able to be resolved.

 

[Skypower]

As for generators, it’s a combination of how clean the power that the generator makes and load put on the generator. Load is “Maximum charging current” (02 setting) PER inverter, plus inverter operating system, plus through put load. Example: lowest charge current that can be set at each inverter 2amps X 4 = 8 8 X 56.4 (default) = 451 watts
Operating System 45? X 4 = 180 watts
House load, some load lights say 300 watts.
So total load is 751watts so theoretically a Honda 2000 inverter generator could easily run this load but if you turn on a microwave the full load would be placed on the poor generator, not load sharing, so keep this in mind when charging with generator through the inverters. This is why many use another charger. If you’re using a generator into the inverters it must have a reasonably good sine wave and stable frequency or the inverters will reject it.

 

[Skypower]

Dup

 

[#40Fan]

Make sure that you are using the current sharing wires, for some reason not shown in the diagrams you posted, between each pair on inverters.

They are the green lines in the diagram below. I think the cables supplied with the inverter are red and black.

 

[Skypower]

Make sure that you are using the current sharing wires, for some reason not shown in the diagrams you posted, between each pair on inverters.

They are the green lines in the diagram below. I think the cables supplied with the inverter are red and black.

Very good point.

 

[garetwo]

What are you settings (28) for each inverter?

I will ask tomorrow, I am going there the day after, this could be an issue!! Thanks!!!

After you’ve set them did you cycle them off to see if the settings kept?

We did not the first time, then read this somewhere and did it. So, when they got turned back on they maintained the setting. It was probably funny to watch a couple of "older" guys frantically checking settings on four inverters to make sure everything was the same and we had the correct phasing.

Was each inverter actually contributing to load or could one just have been in limbo because the setting hadn’t taken?

I will check this.

I think it’s unlikely at this point because it was working, but you may have a different firmware between the new and older inverters. Use the up/down button to display the U1 and U2 versions on each inverter. I don’t know which versions are compatible or if it’s even the issue. If it is the issue it should be able to be resolved.

This is a huge question, I will be asking the client to scroll through tomorrow.

Great info!!!

 

[garetwo]

Very good point.

We do have all of the communication cables in place as well as the current sharing. We had to order a set of the current sharing because the original two inverters were 2P1 and 2P2 and the cables disappeared.

 

[garetwo]

If you’re using a generator into the inverters it must have a reasonably good sine wave and stable frequency or the inverters will reject it.

He has utility connected to the AC input, he does use a 9kw genset to charge the batteries. He told me he had been told the smaller gensets do not work well with the inverter's MPPT charger. I asked Sungold and they confirmed it is not a good idea. Is there a point where the kw would be ok? I saw in one of the threads people "tweaking" the HZ and voltage output of smaller gensets and making them work.

With the small PV array, the utility is doing a lot of charging.

 

[Skypower]

I have a Predator 9500 inverter generator that I have absolutely no problems with. I’m sure that if can run with a smaller unit but you always have to remember that pass through load and have excellent energy management. I’m not going to do a heavy battery recharge then turn on the central air conditioner at the same time even with the Predator.

 

[Skypower]

In my opinion I would only use an inverter type generator because its power is so clean. That being said most inverter generators don’t make power until they are up to speed and up to the moment you shut it off. It either is or isn’t, no ramp up or down. However even for a manual connection with an inverter type, I still start the generator let it stabilize then throw the manual transfer. When I shut down, I disconnect the transfer then shut off the generator. Most whole house emergency generators are not inverter type and they get to speed before they move the automatic transfer switch.

 

[garetwo]

In my opinion I would only use an inverter type generator because its power is so clean. That being said most inverter generators don’t make power until they are up to speed and up to the moment you shut it off. It either is or isn’t, no ramp up or down. However even for a manual connection with an inverter type, I still start the generator let it stabilize then throw the manual transfer. When I shut down, I disconnect the transfer then shut off the generator.

What is the manual transfer switch for? I do not think he has been transferring anything, just connecting to a pure sane wave inverter that WAS permanently connected to the twelve batteries. Right now I think it is just solar and utility. The charge inverter came down to make room for the two more 6548's plus an additional four batteries.

Please remember, when I first walked into space I just figured "this is how it is done". So, this manual transfer switch, please explain what is connected to it.

Most whole house emergency generators are not inverter type and they get to speed before they move the automatic transfer switch.

I know my generac 22kw propane fed is not. I installed when we moved to the rurals 6 years ago - a complete need. Yes, about an eight to ten second startup to transfer time. Knowing what I know now, well, what I think I am beginning to know, I would have preferred a battery bank that could go seven days on just solar. But I also think I now see to get that "big" both in a bank and the solar to charge to 100% could be expensive relative to a genset for charging as needed. Being grid tied there is infrequent periods of partial to several days outage.

 

[Skypower]

What he’s doing probably works better in his case. He doesn’t have to worry about pass through load or picky inverters. The only way I can charge, are my inverters.
Not including the necessary external isolation/ transfer and disconnects. Inside I have a manual selector between grid or generator. If I had to do it again I’d just use a regular small breaker box with an interlock. But this is fast, safe and handles more than double the maximum system load, but not UL.

 

[garetwo]

Inside I have a manual selector between grid or generator. If I had to do it again I’d just use a regular small breaker box with an interlock. But this is fast, safe and handles more than double the maximum system load, but not UL

I like the easy flip over. Looks like a clean installation from the little shown. What is the little meter off the "To House" panel? I also notice the ganged 20amp receptacles....and other stuff (as an electrician).

 

[garetwo]

I am moving over to a different section of this board to address the fault code of 86, I appreciate the input I received in here, thank you. If we get things functioning, I will post our findings. I am heading out to go up there, maybe 40 minutes up into the hills

 

[Skypower]

I like the easy flip over. Looks like a clean installation from the little shown. What is the little meter off the "To House" panel? I also notice the ganged 20amp receptacles....and ither stuff (as an electrician).

I bought two of these things from Amazon to tell me at a glance how well my lines are balanced. Here i was actually pushing an imbalance with some heaters on the same line as a test. I just move my circuits around in the distribution center if I see a pattern. I also use a couple of Emporia Energy devices to dig down and find a pattern.