Sungrow 3 phase inverter, unbalanced output

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dazdaz

21 posts

Geek

#318453 19-Jan-2025 10:16

Hi everyone,

I have a 3 phase 20kW Sungrow SH20RT inverter paired with 19kW of solar panels. The system was commissioned around six weeks ago. We’re on a lifestyle block with reasonably high power usage—currently about 2,200 units per month at this time of year. The system is more than sufficient to cover our energy needs during this period, with our best day of production so far reaching 156 kWh.

One of the reasons I chose the Sungrow inverter was its advertised ability to handle 100% unbalanced loads. However, I’m unable to achieve this in practice. If I set the inverter to export 0 watts, it works as expected, outputting unbalanced power across the three phases to match the property’s load.

The issue arises when export is enabled. In this mode, the inverter balances its output across all three phases, which often leads to simultaneous importing on one phase and exporting on the other two. While this isn’t a problem during peak production in the middle of the day, it becomes an issue early in the morning, late in the afternoon, and likely throughout much of winter when generation is lower.

As the inverter can achieve unbalanced output when export is disabled, it’s clear that the unit is capable of this functionality. However, either the logic or a specific setting appears to be preventing it from working in export mode.

Unfortunately, my installer isn’t very familiar with Sungrow systems, and Sungrow Australia hasn’t been particularly helpful either.

I’m reaching out to see if anyone here has experience with this model or a similar 3 phase Sungrow inverter and has found a setting or workaround to allow unbalanced output while still enabling export. Any advice or insights would be greatly appreciated!

Cheers

SteveXNZ

59 posts

Master Geek

Lifetime subscriber

#3333142 19-Jan-2025 10:58

I can't help with Sungrow, but my 3-phase Alpha T10 inverter has a setting which controls the balance mode. Unfortunately it's not accessible in the standard user configuration settings - the only way I have access to it is by installing a Home Assistant Modbus integration which can query/set the inverter's registers. Hopefully the Sungrow inverter has something similar, and you can access documentation that describes the location and content of the registers.

Certainly for those of us with 3-phase inverters it's important to avoid exporting on one phase and importing on another as we get slugged by the differential tariffs. More critical for me as I can only invert 3.3kW per phase, so quite a bit of analysis goes into load balancing with the inverter doing the best it can to minimise grid import when I'm in a net export situation.

BigTaniwha

2 posts

Wannabe Geek

#3340701 9-Feb-2025 09:06

I have had the same issues.

Exporting on two phases and importing on one.

Go to advanced settings and then to the setting to limit export on each phase. Enable this and then enter a third of you export limit to be on each phase.

In my case I can export 10 Kw so I put in 3.4 kw and 33.4% limit for each phase.

This then stoped the output current being the same on each phase from the inverter and balanced the export current.

dazdaz

21 posts

Geek

#3340714 9-Feb-2025 09:57

BigTaniwha:

I have had the same issues.

Exporting on two phases and importing on one.

Go to advanced settings and then to the setting to limit export on each phase. Enable this and then enter a third of you export limit to be on each phase.

In my case I can export 10 Kw so I put in 3.4 kw and 33.4% limit for each phase.

This then stoped the output current being the same on each phase from the inverter and balanced the export current.

I must be missing something, that is how mine is set. But im still exporting uneven current. See picture I just took. Yours is the SH10T model?

BigTaniwha

2 posts

Wannabe Geek

#3340762 9-Feb-2025 12:37

My Inverter is the SH15T with 17.6 kw of panels but i can only export 10kw to the grid.

I have played around with the settings a bit more and pretty sure I have it right now.

under advanced settings and power control, go down to feed in limitation per phase and enable. then enter the value of kw per phase. ( I set mine to 4 as i don't mind if one is slightly higher as long as I don't import at the same time).

Then set the feed in limitation value. ( I set mine to 67% as 10kw I can export is 67% of the inverter capacity).

If you apply this the settings should work.

do not enable preset feed-in limitation after setting feed in per phase or it will over right it and balance all phases out to the inverter instead of balanced export.

Do you have a limit of export or can you feed everything that you can? if you can set your kw per phase to 6.7 - 7 and the percentage to 100%.

dazdaz

21 posts

Geek

#3340763 9-Feb-2025 12:49

BigTaniwha:

My Inverter is the SH15T with 17.6 kw of panels but i can only export 10kw to the grid.

I have played around with the settings a bit more and pretty sure I have it right now.

under advanced settings and power control, go down to feed in limitation per phase and enable. then enter the value of kw per phase. ( I set mine to 4 as i don't mind if one is slightly higher as long as I don't import at the same time).

Then set the feed in limitation value. ( I set mine to 67% as 10kw I can export is 67% of the inverter capacity).

If you apply this the settings should work.

do not enable preset feed-in limitation after setting feed in per phase or it will over right it and balance all phases out to the inverter instead of balanced export.

Do you have a limit of export or can you feed everything that you can? if you can set your kw per phase to 6.7 - 7 and the percentage to 100%.

Thanks for your reply.

I suspect yours is working because you are generating more than your export limit. If I set my export limit to bellow what the panels are generating then it evens out the phases.

If possible, can you have another look tonight when your panels are only generating around 5kw? I suspect your phases will become unbalanced.

No, I have no export limit, I have 19kw of panels.

BarTender

3606 posts

Uber Geek

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Lifetime subscriber

#3340888 10-Feb-2025 07:01

A friend of mine who also has a Sungrow system said “log a *bug* with Sungrow so it can get escalated to the right person”

He also had a problem with a recent firmware update not correctly changing the batteries and logging the bug managed to eventually get it to the right person who could remotely reconfigure the inverter.

maknij

2 posts

Wannabe Geek

#3355394 20-Mar-2025 02:57

Hi all, I had exactly the same issue on my SH25T and stumbled on the 'Feed-In Limitation for Each Phase' setting myself which when set to 0% resolved my issue and has been fine while I didn't have a need to export.

My utility is now allowing me to export for credits and when I set a feed-in limitation percentage (can be anything) I see the same behaviour again when my phases are unbalanced and there's no PV production like at night-time (ie. 2kw exporting on phase 1 while 1kw is importing on each of the other two phases to balance out). The inverter and DTSU6666 meter in my DB shows net 0 but my utility is charging me for the 2kw imported from the grid during this time, which defeats the whole purpose and costing me for nothing.

Am I missing something else maybe? I made sure 'Feed-In Limitation for Each Phase' is still on, if I set to 0% then the problem goes away, as soon as I set any other percentage the issue is back.

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dazdaz

21 posts

Geek

#3355488 20-Mar-2025 09:45

maknij:

Hi all, I had exactly the same issue on my SH25T and stumbled on the 'Feed-In Limitation for Each Phase' setting myself which when set to 0% resolved my issue and has been fine while I didn't have a need to export.

My utility is now allowing me to export for credits and when I set a feed-in limitation percentage (can be anything) I see the same behaviour again when my phases are unbalanced and there's no PV production like at night-time (ie. 2kw exporting on phase 1 while 1kw is importing on each of the other two phases to balance out). The inverter and DTSU6666 meter in my DB shows net 0 but my utility is charging me for the 2kw imported from the grid during this time, which defeats the whole purpose and costing me for nothing.

Am I missing something else maybe? I made sure 'Feed-In Limitation for Each Phase' is still on, if I set to 0% then the problem goes away, as soon as I set any other percentage the issue is back.

Are you saying that at night, when running on battery power, your system is both exporting energy from the battery and consuming it at the same time? I don’t have a battery on my system, but I did wonder if that might happen.

I've been back and forth with Sungrow technical support in Australia, only to receive conflicting advice from different technicians. Unfortunately, after all that, I never got a clear resolution, and I’m now stuck with an inverter that simultaneously imports and exports power.

This isn’t an issue during the day when there’s full sun, as I can generate enough power on each phase to cover my loads. However, on cloudy days with low production, or in the mornings and evenings, it’s definitely noticeable.

maknij

2 posts

Wannabe Geek

#3355727 20-Mar-2025 20:05

Yes correct. Actually, it's not just at night when there's no PV, it's whenever there's no surplus to export and I have disparate loads on the different phases (like running single phase aircons). Here's a view around 11:30am yesterday where there was plenty of PV but my battery was still charging, so there wasn't any surplus to export yet:

Then from my utilities portal I can see this effect too - see below. On 17 Mar I set a 30% export limit, prior to 17 Mar I only ever saw consumption when my battery ran flat. From 17 Mar onwards I see the issue outside of the periods I'm not exporting surplus PV (I've highlighted these in green). As soon as I start exporting it's fine.

First prize I can get my utility to enable net metering to combine the phase values instead of metering me on the individual phases, since in reality at 11:30am yesterday I wasn't really consuming anything, my inverter was just using the grid to balance my phases out due to disparate loads - I was 100% using all available PV. Net metering is probably best overall too as even when I set export to 0% there's always a tiny bit of import/export happening as the inverter is working to limit the individual phases and over time this adds up too. Second prize there's a firmware update or specific firmware revision which allows the inverter to do a proper job at limiting unnecessary import on the individual phases.

dazdaz

21 posts

Geek

#3355732 20-Mar-2025 20:28

I was told by Sungrow that they had a “special” firmware that would allow the inverter to output uneven on each phase, they upgraded my firmware to that, but it made no difference to the import/ export at the same time issue. Net metering would solve the issue, but unfortunately its not available in NZ