Sunny Island SI-6048 with Sunny Boy 8000-US, RS485 vs. UL 1741

[duerrd561]

Hi everyone! I'm hoping someone here might be able to help me answer a question that I'm really struggling to get a reliable answer on from SMA. But first, I will introduce my system and share details on the setup. Hopefully others might find this detail interesting.

I have a rural property in central California with PG&E NEMS service. At a high level, my setup consists of:

• A pair of Sunny Island 6048-US inverters on a 490Ah battery bank.
• A primary 9.8kW SunPower solar array with an older (SunPower-branded) Sunny Boy 8000-US.
• A secondary 4.5kW solar array with a newer Sunny Boy 5.0-US.
• An automatic transfer switch (ATS) wired between the main service entrance panel and the main load center (tandem panel).
• An RS485 connection between a WebBox, the older Sunny Boy 8000-US, and the master Sunny Island.

On the Sunny Islands, AC2 connects to a breaker in the main service entrance panel (in front of the ATS) and AC1 is connected to a sub panel that feeds critical loads, the primary solar array's Sunny Boy 8000-US, and the "generator" input of the ATS via a "load shedding" contactor controlled by a Sunny Island relay. When the grid is down, the whole property has power until the battery SoC falls below a threshold yet low-power critical loads can be maintained directly off AC1 until the Sunny Islands shut down due to full battery discharge. The primary solar array can recharge the batteries so long as the Sunny Islands are powered on, even when the rest of the loads are shed due to low SoC. The secondary solar array can run as long/soon as the battery SoC is high enough to engage the contactor and feed the "generator" power to the rest of the property. And of course when the grid is up, both solar arrays back-feed to the grid.

Both Sunny Boy inverters are configured in "grid-backup" mode, and everything behaves as I would expect across both inverters when the grid is up, the grid is down, the battery SoC is full without enough loads, or the battery SoC is low and the load shedding is in place. But the secondary array's inverter does not have an RS485 card and thus cannot communicate with the Sunny Island over the RS485 bus at all. Yet, both solar inverters are clearly "communicating" with the Sunny Island's phase shifting when it needs them to derate their output due to being off-grid with full battery SoC and not enough loads. I know this because I see some older Insteon light switches flickering when the phase shifting occurs, and also because I have checked the frequency and inverter output during such times as these and can see the phase shifted. And I believe this functionality is coming from the fact that both inverters implement UL 1741, not from any RS485 capability which only one of the inverters even has.

So, what functionality am I gaining by having the older Sunny Boy 8000-US and the Sunny Island connected via RS485, beyond the ability to monitor and/or configure them via the WebBox?

The reason for my question is that the older Sunny Boy 8000-US inverter is beginning to fail (intermittently going into "Disturbance" mode) and I need to replace it. Luckily my SunPower modules were one of the first to not require positive grounding, so I can at least entertain a newer transformer-less inverter. If I can't get an SMA inverter that is capable of talking RS485 with the Sunny Island then I'll be forced to buy a Data Manager M which is quite expensive, and overkill for my needs. So I am trying to understand what functionality I would lose if the Sunny Island no longer had RS485 communication with either solar inverter.

Thanks in advance for your help!

-- edited to correct reversed AC1/AC2 labels

 

[kommando]

The RS485 is only need for those Sunny Boys that can be on grid and then off grid and need to be told by the SI when to change from on to off and back to on grid. For the older SB's the RS485 allows you to monitor them but the SI will only control, their output using the frequency change if their are in off-grid mode, this is changed using the rs485, Sunny Data Control on a PC and a Grid Guard code.

I have a newer SB3600TL-21 with Bluetooth access only, using a PC with Bluetooth, Sunny Explorer and a Grid Guard code I changed it from G59 UK grid tied to Off Grid. No need for a Data Manager M.

Older SMA inverters are available in the UK 2nd hand, all mine are 2nd hand and none cost more than £120.

 

[duerrd561]

The RS485 is only need for those Sunny Boys that can be on grid and then off grid and need to be told by the SI when to change from on to off and back to on grid. For the older SB's the RS485 allows you to monitor them but the SI will only control, their output using the frequency change if their are in off-grid mode, this is changed using the rs485, Sunny Data Control on a PC and a Grid Guard code.

I have a newer SB3600TL-21 with Bluetooth access only, using a PC with Bluetooth, Sunny Explorer and a Grid Guard code I changed it from G59 UK grid tied to Off Grid. No need for a Data Manager M.

Older SMA inverters are available in the UK 2nd hand, all mine are 2nd hand and none cost more than £120.

Thanks for the reply, kommando. Makes sense and seems to line up with my experience.

As I think about the setup more, it seems like the fact that this inverter is AC-coupled directly into AC2 means that it is thus *not* directly connected to the grid, and as such its UL 1741 functions (i.e. shutoff when no grid power is present) are actually being performed by the Sunny Island sitting between it and the grid. So as you said in your note, the only reason this inverter even needs to be put into the "grid-backup" or "off-grid" mode is so that it can respond to the *phase shifting* put out by the Sunny Island when it wants some power, but not all the power, produced. Am I making sense here?

 

[kommando]

Yes, the SI frequency is a curve not an on off switch, so it can change the SB's output gradually from 100% to 0%.

 

[duerrd561]

Yes, the SI frequency is a curve not an on off switch, so it can change the SB's output gradually from 100% to 0%.

Makes sense, and I've definitely seen it behave like that.

So in your opinion, would I notice any functional difference if I replaced the SB 8000-US with, for example, a newer SB7.7-1SP-US-41 that did not have RS485 but which was put into "grid-backup" mode? I'd then just reduce the WebBox's use to the Sunny Island only.

 

[kommando]

Not up to speed on the newer ones, they should be accessible on your local network with their own webpage, you get 10 hrs to change the mode and after the 10 hrs then to change mode you need a Grid Guard code.

Stand-alone grid Island Mode 50Hz / Island Mode 60Hz

 

[1201]

Makes sense, and I've definitely seen it behave like that.

So in your opinion, would I notice any functional difference if I replaced the SB 8000-US with, for example, a newer SB7.7-1SP-US-41 that did not have RS485 but which was put into "grid-backup" mode? I'd then just reduce the WebBox's use to the Sunny Island only.

my sunny island phase shifts my growatt inverter perfectly, without any comms at all. I had to tweak some settings on the growatt to allow full control without the growatt shutting off.

I think the only problem you may have with an sb7.7 us is that it has to be set to ca rule 21 and the sunny island may not be able to throttle the output down to zero without shutting it off.

 

[duerrd561]

my sunny island phase shifts my growatt inverter perfectly, without any comms at all. I had to tweak some settings on the growatt to allow full control without the growatt shutting off.

I think the only problem you may have with an sb7.7 us is that it has to be set to ca rule 21 and the sunny island may not be able to throttle the output down to zero without shutting it off.

Thanks for the response, 1201! Makes sense and reassuring to hear your experience there.

As it turns out, the SB7.7-US is not even available any more due to SMA being completely backordered, and having introduced yet another change in their lineup. I was favoring this particular model because at least it has the option of adding an RS485 card to it. But if I can't get it, then it doesn't matter. So, I'm having to consider other manufacturers -- the Tigo EI 7.6kW has come up a few times as a recommendation. If I change to something like this, then RS485 is not even an option anymore.

 

[kommando]

Whatever you go to to be able to work with the SI in off grid is best to have have a frequency control, @1201 has confirmed his Growatt does this and I have confirmed that EU Solax's will do this also. If it does not have frequency control then, if your battery is large enough and can handle some overcharge for a few mins, then you set the grid cutoff top frequency to say 61.7htz and then once the SI pushes past 61.7htz the inverter will stop dead with a sudden shutdown.

 

[1201]

Thanks for the response, 1201! Makes sense and reassuring to hear your experience there.

As it turns out, the SB7.7-US is not even available any more due to SMA being completely backordered, and having introduced yet another change in their lineup. I was favoring this particular model because at least it has the option of adding an RS485 card to it. But if I can't get it, then it doesn't matter. So, I'm having to consider other manufacturers -- the Tigo EI 7.6kW has come up a few times as a recommendation. If I change to something like this, then RS485 is not even an option anymore.

I'm pretty sure the tigo is a rebranded growatt min xh us. Get the growatt and you save some dollars

Growatt 7.6kW Grid-Tie Inverter | MIN 7600 XH-US

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

 

[duerrd561]

I'm pretty sure the tigo is a rebranded growatt min xh us. Get the growatt and you save some dollars

Growatt 7.6kW Grid-Tie Inverter | MIN 7600 XH-US

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

Wow! You're not kidding about saving some dollars. That's a super reasonable price, and it looks like a really great design with a lot of useful features. I love that there is a Home Assistant integration for it as well! Now that you've got me interested, what are some of your other favorite things about this inverter?

 

[1201]

Wow! You're not kidding about saving some dollars. That's a super reasonable price, and it looks like a really great design with a lot of useful features. I love that there is a Home Assistant integration for it as well! Now that you've got me interested, what are some of your other favorite things about this inverter?

1. 600v mppts
2. Works very nicely AC coupling to other inverters and has high adjustability
3. It works with solar assistant-this is a big deal for me because solar assistant updates every second vs every 5 minutes with the growatt app
4. It's very affordable
5. I like the efficiency. It's pretty much 97.5% from low output to max output.

 

[kommando]

Only issue I have with these Chinese inverters is the data collection gets sent to China for viewing in the cloud. For my Solax I grab the data before it gets sent and have my own data logger. Solax do not do it but some use the access this gives to do unannounced firmware upgrades.

 

[duerrd561]

1. 600v mppts
2. Works very nicely AC coupling to other inverters and has high adjustability
3. It works with solar assistant-this is a big deal for me because solar assistant updates every second vs every 5 minutes with the growatt app
4. It's very affordable
5. I like the efficiency. It's pretty much 97.5% from low output to max output.

Right on! Thank you.

Speaking of adjustability, what did the process look like to switch it into "backup" mode so that it'd phase shift w/ the Sunny Island when off grid? I know on SMA you had to make the switch quickly after deployment, or suffer having to get the dreaded "grid guard" code.

 

[duerrd561]

Only issue I have with these Chinese inverters is the data collection gets sent to China for viewing in the cloud. For my Solax I grab the data before it gets sent and have my own data logger. Solax do not do it but some use the access this gives to do unannounced firmware upgrades.

Thanks kommando. I can appreciate and do share this sensitivity. The good news for me is that I already rolled my own monitoring solution through Home Assistant using Shelly EMs and Shelly I4s. The Shelly EMs have CTs that monitor production, voltage, phase, etc. And the Shelly I4s monitor relays on the Sunny Island to tell me what's going on. So it wouldn't be a problem for me to either (a) not provision the Wi-Fi on this inverter at all, or (b) provision the Wi-Fi but block its cloud access at the router.

 

[Hedges]

Hi everyone! I'm hoping someone here might be able to help me answer a question that I'm really struggling to get a reliable answer on from SMA. But first, I will introduce my system and share details on the setup. Hopefully others might find this detail interesting.

I have a rural property in central California with PG&E NEMS service. At a high level, my setup consists of:

• A pair of Sunny Island 6048-US inverters on a 490Ah battery bank.
• A primary 9.8kW SunPower solar array with an older (SunPower-branded) Sunny Boy 8000-US.
• A secondary 4.5kW solar array with a newer Sunny Boy 5.0-US.
• An automatic transfer switch (ATS) wired between the main service entrance panel and the main load center (tandem panel).
• An RS485 connection between a WebBox, the older Sunny Boy 8000-US, and the master Sunny Island.

On the Sunny Islands, AC1 connects to a breaker in the main service entrance panel (in front of the ATS) and AC2 is connected to a sub panel that feeds critical loads, the primary solar array's Sunny Boy 8000-US, and the "generator" input of the ATS via a "load shedding" contactor controlled by a Sunny Island relay.

I think you mean AC2 connects to main service panel, AC2 to critical loads.

When the grid is down, the whole property has power until the battery SoC falls below a threshold yet low-power critical loads can be maintained directly off AC2 until the Sunny Islands shut down due to full battery discharge. The primary solar array can recharge the batteries so long as the Sunny Islands are powered on, even when the rest of the loads are shed due to low SoC. The secondary solar array can run as long/soon as the battery SoC is high enough to engage the contactor and feed the "generator" power to the rest of the property. And of course when the grid is up, both solar arrays back-feed to the grid.

Does your ATS have at least a 5 second "off" time when switching between sources?
Don't want SB sync'd to SI frequency, then snapped over to grid out of phase without long enough delay for it to disconnect.

Both Sunny Boy inverters are configured in "grid-backup" mode, and everything behaves as I would expect across both inverters when the grid is up, the grid is down, the battery SoC is full without enough loads, or the battery SoC is low and the load shedding is in place.

Is Sunny Boy 5.0-US the -41, -40, or another model?

Those do not have "backup" mode, choices include UL-1741, Rule-21, offgrid

But the secondary array's inverter does not have an RS485 card and thus cannot communicate with the Sunny Island over the RS485 bus at all. Yet, both solar inverters are clearly "communicating" with the Sunny Island's phase shifting when it needs them to derate their output due to being off-grid with full battery SoC and not enough loads. I know this because I see some older Insteon light switches flickering when the phase shifting occurs, and also because I have checked the frequency and inverter output during such times as these and can see the phase shifted. And I believe this functionality is coming from the fact that both inverters implement UL 1741, not from any RS485 capability which only one of the inverters even has.

Sunny Boy 8000-US implements UL-1741 without frequency-watts. When commanded via RS-485, its display will indicate grid-backup. Then it supports wider frequency and voltage without disconnecting, and frequency-watts ramps down from 100% at 61 Hz to 0% at 62 Hz (if left at default settings)

Sunny Boy 5.0-US, (if it has recent enough firmware, I think) has UL1741-SA Rule-21 frequency-watts which ramps down from 100% at 60.5 Hz to 0% at 61 Hz.

So, what functionality am I gaining by having the older Sunny Boy 8000-US and the Sunny Island connected via RS485, beyond the ability to monitor and/or configure them via the WebBox?

You get switching between UL-1741 (default 59.7 Hz to 60.5 Hz) and anti-islanding without frequency watts and off-grid (56 Hz to 64 Hz with frequency-watts).
Without RS-485 it would work set to offgrid, but would not have anti-islanding. Sunny Island performs anti-islanding and disconnects from grid when grid goes down.
However, if Sunny Island gets its relay welded shut (I understand that does happen), you would have 8000-US on-grid without anti-islanding, potentially a safety risk for lineman.

In a video, SMA America recommended setting SB -41 to offgrid when operated behind SI. That disagrees with SMA Germany's written instructions.
I don't know why they made that recommendation. I am concerned about welded relay in SI.

The reason for my question is that the older Sunny Boy 8000-US inverter is beginning to fail (intermittently going into "Disturbance" mode) and I need to replace it.

Does it say what disturbance is? Frequency, something else?
Does that happen on grid? Off grid?

Try shutting off the newer SB 5.0, in case it is source of disturbance.

Luckily my SunPower modules were one of the first to not require positive grounding, so I can at least entertain a newer transformer-less inverter.

Or an older model, used or new old stock.
See SMA's list of which inverters support backup mode; not all do.

Good that you know about PID.
I want to operate all my panels either positive or negative grounded, even if supposedly PID free (just greatly reduced.)
One of my inverters just got bricked, and for now have moved SunPower 327W array from SunPower branded SB 8000US over to a transformerless 10000TL-US-12 (which doesn't properly support backup mode so is set to offgrid/Island.)

If I can't get an SMA inverter that is capable of talking RS485 with the Sunny Island then I'll be forced to buy a Data Manager M which is quite expensive, and overkill for my needs. So I am trying to understand what functionality I would lose if the Sunny Island no longer had RS485 communication with either solar inverter.

What benefit does Data Manager M give you? I haven't used it.

Thanks in advance for your help!

I have connected and operated an SB -41 but not checked it closely yet.
I'm testing SBS, which seems to be based on same design. The current wave form I measured was not a nice sine wave, had a large 7th harmonic (420 Hz) riding on top. Maybe that interferes with SB-8000.

I think the only problem you may have with an sb7.7 us is that it has to be set to ca rule 21 and the sunny island may not be able to throttle the output down to zero without shutting it off.

That is my suspicion. SI would overshoot slightly above 61 Hz. And for OP's system, would drive up to 62 Hz to zero output of SB 8000.
Not clear to me whether Rule 21 should disconnect immediately above 61 Hz (like UL-1741 SA without Rule 21) or ride through.

With grid-guard, you could make some changes so both SB work over same frequency range to ramp power (if desired) and ride through high enough to stay on line while either ramps and for overshoot.

As it turns out, the SB7.7-US is not even available any more due to SMA being completely backordered, and having introduced yet another change in their lineup.

Some are out there. Here's one that got dropped and case broken. Current bit $255, but freight shipping was quoted at $450.
I told him it could go common carrier for $200 but he didn't want to.

SMA Sunny Boy SB7.7-1SP-US-41 Solar Power Unit | eBay

We are experts in e-waste recycling, re-use, removal, and secure data destruction. No matter what your struggle is in managing your excess assets, leave it to us. We’ll C2 it. DATA DESTRUCTION. ASSET RECOVERY.

www.ebay.com

But I prefer SB 5000US series.

 

[1201]

Only issue I have with these Chinese inverters is the data collection gets sent to China for viewing in the cloud. For my Solax I grab the data before it gets sent and have my own data logger. Solax do not do it but some use the access this gives to do unannounced firmware upgrades.

He could use solar assistant and never connect to the Chinese server but I understand your point

 

[1201]

Right on! Thank you.

Speaking of adjustability, what did the process look like to switch it into "backup" mode so that it'd phase shift w/ the Sunny Island when off grid? I know on SMA you had to make the switch quickly after deployment, or suffer having to get the dreaded "grid guard" code.

There is no mode. It phase shifts out of the box. But after a number of seconds above 60.5 hz, it would shut down. I had to adjust the settings to get 100% control below 60.5 hz so it never shuts down. It starts throttling at 60.04 hz and is down to zero without shutting down usually around 60.42hz

 

[duerrd561]

I think you mean AC2 connects to main service panel, AC2 to critical loads.

Thank you for the correction. I was going off memory, and had them backwards. I've corrected the original post above.

Does your ATS have at least a 5 second "off" time when switching between sources?
Don't want SB sync'd to SI frequency, then snapped over to grid out of phase without long enough delay for it to disconnect.

The ATS does not have a 5 second "off" time when it switches -- I'd say it's about a 500ms switch time from grid to generator, and a 250ms switch time from generator back to grid. Slow enough to kill power to computers, or to reset the oven clock. But it also has a 5-minute delay for grid stabilization before switching from generator back to grid, and when this process is occurring the Sunny Island has independently seen the return of grid power on AC2 and presumably gone through some sort of process to resync itself with that frequency such that when the 5-minute switchover occurs, you generally don't notice it happened.

Is Sunny Boy 5.0-US the -41, -40, or another model?

Those do not have "backup" mode, choices include UL-1741, Rule-21, offgrid

I apologize, but I am not sure. My primary residence is not at the house, and I cannot get the specific model suffix from the portal on the device. I bought it in 2016, and I have a hunch it is the -40 since it is running (and maxes out at) an older firmware version. It looks like it is set to Island Mode 60Hz. The other options available in the picklist are Default, HECO2017, UL1741/2016, and WorstCase.

Sunny Boy 8000-US implements UL-1741 without frequency-watts. When commanded via RS-485, its display will indicate grid-backup. Then it supports wider frequency and voltage without disconnecting, and frequency-watts ramps down from 100% at 61 Hz to 0% at 62 Hz (if left at default settings)

Sunny Boy 5.0-US, (if it has recent enough firmware, I think) has UL1741-SA Rule-21 frequency-watts which ramps down from 100% at 60.5 Hz to 0% at 61 Hz.

Got it. So I think what you're saying is that the SB 8000-US *requires* RS485 to properly work with the Sunny Island in "grid-backup" mode. In other words, I would not have been able to make this older inverter work without RS485. Did I understand that correctly?

You get switching between UL-1741 (default 59.7 Hz to 60.5 Hz) and anti-islanding without frequency watts and off-grid (56 Hz to 64 Hz with frequency-watts).
Without RS-485 it would work set to offgrid, but would not have anti-islanding. Sunny Island performs anti-islanding and disconnects from grid when grid goes down.
However, if Sunny Island gets its relay welded shut (I understand that does happen), you would have 8000-US on-grid without anti-islanding, potentially a safety risk for lineman.

In a video, SMA America recommended setting SB -41 to offgrid when operated behind SI. That disagrees with SMA Germany's written instructions.
I don't know why they made that recommendation. I am concerned about welded relay in SI.

Fascinating. And scary thought about the relay welding shut, but it makes sense that the possibility exists.

Does it say what disturbance is? Frequency, something else?
Does that happen on grid? Off grid?

Try shutting off the newer SB 5.0, in case it is source of disturbance.

It shows "Disturbance VacL1-Bfr". It's been running alongside the SB 5.0 and the Sunny Islands, in the configuration described above, for ~8 years with no issues. It's hard to imagine that it is suddenly being disturbed by the SB 5.0, now.

Or an older model, used or new old stock.
See SMA's list of which inverters support backup mode; not all do.

Yes, I tried this route. Unfortunately the guys who do this don't have SB 8000-US anymore. And I'm just not super interested in riding the SMA train here given the high cost and what I'd argue is a questionable product management strategy.

Good that you know about PID.
I want to operate all my panels either positive or negative grounded, even if supposedly PID free (just greatly reduced.)
One of my inverters just got bricked, and for now have moved SunPower 327W array from SunPower branded SB 8000US over to a transformerless 10000TL-US-12 (which doesn't properly support backup mode so is set to offgrid/Island.)

Interesting. So you're a fellow SunPower user? Did your modules claim to not require positive grounding like mine? Tigo's web site talks about a new device they are working on incorporating which goes between the array strings and the inverter and helps mitigate PID. It looked promising, but not yet available for sale.

What benefit does Data Manager M give you? I haven't used it.

It appears to be their latest comm bus that interconnects all their competing communication protocols. I am honestly not super impressed with the number of variants they've created in the first place. Hence, combined with the high price tag, my lack of interest in supporting their latest variant.

Thanks again for your detailed responses here.

 

[duerrd561]

There is no mode. It phase shifts out of the box. But after a number of seconds above 60.5 hz, it would shut down. I had to adjust the settings to get 100% control below 60.5 hz so it never shuts down. It starts throttling at 60.04 hz and is down to zero without shutting down usually around 60.42hz

Got it, thanks. This seems to line up with even SMA's own products more recently, where they claim to enable "grid-backup" behavior by default now, right out of the box. I suspect they got tired of everyone asking for "grid guard" codes?

Where did you have to make the settings adjustments you mentioned? In the Sunny Island, or in the Growatt?