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Sunny Boy Grid Tied Inverter in Island Mode 60hz

Calvin98 said:
Isn't it the Sunny Islands? I have seen say 3,400watts on the "master" and say 2,400 watts on the "slave." Since Master is on L1 and slave on L2, it would be interesting to see if that goes all the way back to the Sunny Boys also. If the battery is full, it might. I seem to remotely remember L1 and L2 on an SB not being 100% the same. Been a while since we had a power outage. But still since the SI is the "gate keeper" for the local grid, I'd assume it was in charge of all of it.
Click to expand...
The imbalance is managed by the Sunny Islands. The Sunny Boy grid inverters will always put out almost equal amounts on both legs.
 
MurphyGuy said:
You should be using a SINGLE battery bank connected to both Sunny Islands.. DO NOT use one bank for each.. they need to feed off the same 48v source.. In fact, from my understanding, even the DC Cables should be approximately the same length.
Click to expand...
I know that the SI manual says the AC lines should be the same length, but the battery cables also? If so, that is probably to have the same resistance in the lines to the all of batteries so they can charge/discharge equally? So some difference in length could be ok so long as it was not excessive - like 2/0 wire to 3 batteries and 4ga to the 4th battery. i.e 5' of 2/0 wire to 3 batteries and 4.5' of 2/0 wire to 4th battery probably ok?

The SMA tech guys said to get the AC wires "close" in length. +/- a few inches is ok, just not several feet difference in length. I did not ask about battery cable length.
 
BobK53 said:
Item 2: You stated that your Sunny Boy PV inverters can be set to “Island Mode.” I cannot find anything in the Installation Guide that came with the SB Inverters or anything else that I’ve been able to get from SMA. Wording in the Installation Guide indicates that without the grid connected only 2,000W of power can be used through the Secure Power Supply Operation, after I flip the switch. That is only 1/3 of the total power output of the SB 6.0 inverters.
Click to expand...

If you have newer Sunny Boys (ethernet connection), you can use the Sunny Explorer to change the settings. Use the installer password to enter the program. Then under SETTINGS-> Grid Monitoring you can set the country standard as "SMA Island Mode 60Hz"
 
I'm using AGM with Sunny Island, have no precharge.
Other forum members with DIY lithium and relay have welded their relays.

Wonder how this is addressed with supported lithium batteries?
BYD B-Box is one. Only found a single web page, a data sheet, on their site and no mention of precharge.



This 10kW, $20k (delivered) model also says SMA compatible:

sunwatts.com

10.2 kWh BYD Battery-Box H10

The 10.24kWh BYD B-Box (Battery Box) HV Battery Storage is a high voltage, lithium battery with a battery control unit (BCU). Designed with the safe lithium iron phosphate (LiFePO4) battery chemistry, the B-Box is the ideal battery storage solution for residential and commercial applications...
sunwatts.com sunwatts.com


I find some old manuals. No mention of "precharge" or "inrush"


"High-voltage" batteries with low-voltage battery and boost converter are inherently current limited.
Directly used low-voltage batteries could have precharge resistor, or FET BMS with ramp-up function.
I expect to read about these things in specs. But for supported pairings, may only be dealt with between manufacturers and not disclosed to customers.
 
Hedges said:
I'm using AGM with Sunny Island, have no precharge.
Other forum members with DIY lithium and relay have welded their relays.

Wonder how this is addressed with supported lithium batteries?
BYD B-Box is one. Only found a single web page, a data sheet, on their site and no mention of precharge.



This 10kW, $20k (delivered) model also says SMA compatible:

sunwatts.com

10.2 kWh BYD Battery-Box H10

The 10.24kWh BYD B-Box (Battery Box) HV Battery Storage is a high voltage, lithium battery with a battery control unit (BCU). Designed with the safe lithium iron phosphate (LiFePO4) battery chemistry, the B-Box is the ideal battery storage solution for residential and commercial applications...
sunwatts.com sunwatts.com


I find some old manuals. No mention of "precharge" or "inrush"


"High-voltage" batteries with low-voltage battery and boost converter are inherently current limited.
Directly used low-voltage batteries could have precharge resistor, or FET BMS with ramp-up function.
I expect to read about these things in specs. But for supported pairings, may only be dealt with between manufacturers and not disclosed to customers.
Click to expand...
I smoked a 300amp Chargery DCC contactor by not using precharge. The irony was that the DCC claimed to have a soft start. Turns out their softstart is only when you flip the manual switch on the front cover. Not when the individual mosfets are commanded on electrically.
 
REC supports precharge:

diysolarforum.com

Has anyone been able to get REC to fully charge a battery?

Yeah, I think I was being too conservative with my numbers. I switched back over to the off-grid system for tonight to let the pack drain down to 3.7-ish. Then I'll fire up the solar again in the morning and it will charge at 100+ amps. Lets see if it will race up to the 4.1 (End of...
diysolarforum.com diysolarforum.com
 
SMA RELPY to question: Do you need a pre charge resistor for Sunny Island?

"Greetings

Short answer is no, but please read the manual for detailed explanation."
 
:ROFLMAO:

The manual explains a great deal in detail, but does not contain the words "precharge" or "inrush".

My guess is, if you use a lithium battery from their approved list, it implements current limiting.
If you go your own way, e.g. REC BMS with LiFePO4, you do need to precharge (based on the experience of another forum member.) He reported doing that with a GigaVac contactor to SI and it welded. REC does have a precharge solution. Better use that, or your own home-brew solution.
 
Right. I asked the same question and asked them to be more specifice as to what pages to read. Their reply was that I should call them back.
Still not 100% sure. Still have a lead acid batter as of now.
 
If I used an external precharge switch for my 4x SI, it should be rated 480A continuous.
Only needed when closing breakers on each SI, something infrequent. And for lithium, not lead-acid. Simply unbolting a battery cable, connecting through a 1500W space heater (10 ohms) should do it.
 
Hedges said:
Only needed when closing breakers on each SI, something infrequent. And for lithium, not lead-acid. Simply unbolting a battery cable, connecting through a 1500W space heater (10 ohms) should do it.
Click to expand...
Do you have a diagram for that? Not sure what you mean. I have an anderson connector that goes from the battery to the SI. Now, I connect that, then turn the SI breakers on. If and when I switch to lithium, I'll need the "space heater resistor" when connecting?
 
Resistor in series between battery and inverter to precharge capacitors first, then short out or replace resistor with direct wire.

I would suggest turning SI breakers on first, inserting an Anderson "Precharge" cable with space heater in series. Wait for voltage to come up on SI side connector. Then unplug "Precharge" cable and mate battery/inverters cable directly.

Alternatively, out the back of the big Anderson connectors, connect smaller wires. Those go through space heater and smaller Anderson. Mate the smaller Anderson Precharge connector first, then after voltage comes up short it out by mating big Anderson connector.

SI draws 4W, 80 mA, on standby. So 1/3 amp for my 4x SI. 1/3A x 10 ohms = 3.33V, about 7% of battery voltage.
Not sure if I have 0.4F or what exactly among the inverters. 0.4 amp-seconds per volt, 1 volt per second decay.
 
Hedges said:
Resistor in series between battery and inverter to precharge capacitors first, then short out or replace resistor with direct wire.

I would suggest turning SI breakers on first, inserting an Anderson "Precharge" cable with space heater in series. Wait for voltage to come up on SI side connector. Then unplug "Precharge" cable and mate battery/inverters cable directly.

Alternatively, out the back of the big Anderson connectors, connect smaller wires. Those go through space heater and smaller Anderson. Mate the smaller Anderson Precharge connector first, then after voltage comes up short it out by mating big Anderson connector.

SI draws 4W, 80 mA, on standby. So 1/3 amp for my 4x SI. 1/3A x 10 ohms = 3.33V, about 7% of battery voltage.
Not sure if I have 0.4F or what exactly among the inverters. 0.4 amp-seconds per volt, 1 volt per second decay.
Click to expand...
Just to pile on.... a buddy used 100ohm resistor for precharge at his battery. He called me worried because lights were on the SI's but they didn't boot. We powered them up one at a time via the 100ohm resistor and they came up. So he's replaced 100ohm with 10ohm. Now you can throw both breakers at the same time and they both boot correctly. Voltage rising too slowly on the SI capacitors must trigger the brownout circuit.
 
crazydane said:
Any word on when then SI 8.0H will be stateside?

It looks very nice.

Click to expand...
I feel you.... the US market SI 6048s have different transformer inside to make 120v. I'm not sure SMA wants to make a product for north america... I feel like a red headed step child.... or a red white and blue headed step child. My neighbor just got yasdi going so we have a work around for not being able to get sunny web boxes. We can get data into a mqtt server and not muck with modbus now atleast.
 
A single transformer design with 2x 120V windings could connect series vs. parallel.
Just as some American brands do for 120/240V split-phase vs. 120V only.
That could also give us split-phase, on the Island side, with a single SI.

A couple filter and transient suppressor components different, and it could easily support both markets. Could even be stuffed so only a jumper configures it.

The 8.0H apparently has support for 200A external transfer switch. Think it also can use internal relay. But the details aren't 100% clear to me.

My guess is that load shaving features would come to the U.S. with the 8.0H. Presently, only Sunny Boy Storage supports that.
 
crazydane said:
Any word on when then SI 8.0H will be stateside?

It looks very nice.
Click to expand...

But pricewise, I expect it to be $5000+. MSRP of 6048US is $5700, retail street price around $4700.

If you can get a deal on 6048US, I think that is the thing to do.

I do note that 6048US, being UL-1741 not UL-1741-SA, is no longer on the approved lists. However, it is UL listed.
What I think that *SHOULD* mean is not approved as an inverter to drive PV into the grid (which it would do only with external DC coupled PV), but as a UPS it should be acceptable. Just happens to be a UPS with GT PV connected on its island side.
 
A guy on marketplace has 4 of the 6048US brand new sealed on a pallet for $2,900 each. But looking at the shipping label, it looks like they are NOS as it shows 2017. Perhaps not a big deal as they do have a 10 year warranty. The Power Store, where I got my SBs from, has them for $3,466, which seems like a pretty decent deal as well.

@Hedges Do you have a writeup of your system somewhere on this forum?
 
Decent bargain these days. But the bundle with Midnight boxes includes some balance of system hardware that may be worth the additional money.

www.stellavolta.com

MidNite Solar MNSI6048-QUAD Pre- Wired AC Coupled System

Shop now for MidNite Solar MNSI6048-QUAD Pre- Wired AC Coupled System.
www.stellavolta.com www.stellavolta.com

diysolarforum.com

Solar Power with Grid Backup

Wow, that’s a lot of power! Yes, about 2x the PV that would be needed if gas heat used. Also 2x the Sunny Island battery inverter needed. They only have 56A relay for pass-through from grid, and because I got them cheap enough I doubled up for 112A at 120/240V If you got two Sunny Island...
diysolarforum.com diysolarforum.com

Not on the forum, not on my computer, not on paper. It's all in my head.
The only thing I can point to is SMA Sunny Island data sheet with block diagram.
I have grid feeds 4x SI feeds SB & loads.

I also assembled a test rig with one SI and DC coupled Sunny Island Charger.
Then changed to 3x SI 120/208Y, transformer, Sunny TriPower.

I should do a good block diagram eventually, with all sub panels and their interlocked breakers. The design is still evolving toward final form.
 
Last edited:
That does look like a decent package deal.

So what BMS units are compatible with the SIs? I looked at the list of approved lithium-ion batteries and they all look like VERY expensive turn key solutions. Can I roll my own DIY raw LiFePO4 cells with, say Overkill BMSs? Alternatively, can I use the EG4 server rack batteries, for example?
 
REC is one we know that offers SI compatible BMS. At least a couple forum members use it. One recently was asking questions about settings to reach full charge, which wasn't happening for him. I think someone responding was from REC, not sure.
I think they have other protocols as well.
It would use external battery shunt and external disconnect relay. They also sell a precharge device.

People have used SI without BMS communication, telling SI the battery is VRLA. I would rather have the communication.
 
Thanks, so I guess more specifically one or more of the REC-BMS Q-BMS 16S, depending on how large a battery bank I want to build?

Man, this sure is starting to add up...
 
crazydane said:
Thanks, so I guess more specifically one or more of the REC-BMS Q-BMS 16S, depending on how large a battery bank I want to build?

Man, this sure is starting to add up...
Click to expand...
The SMA / REC combo is expensive. I’ve been watching off-grid systems for over a decade, and seeing so many “cheaper” combinations fail early has convinced me i can’t afford to buy anything cheaper.
 
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