Hi all.

I'm 10 days into life with my SunSynk. (Sunsynk 5KW, Dyness 4.8 KWh, 3.2 KW PV) I've managed to do a few good optimizations resulting in reducing the amount of power imported and maximizing the amount of Solar that I actually use.

So, the next adjustment I wanted to try was to switch the Inverter mode from "Zero-Export + Limit to Load Only", to just "Zero-Export". I did this early this morning, when the battery was low, and the Sun had not started delivering power yet.

As per my (possibly incorrect) understanding, this would allow the inverter to push excess power to help feed the non-essential load (sitting between the Inverter and the CT), which is just my geyser and oven. But it would not export anything beyond the CT, since it is "Zero-Export".

However, it behaved very differently from my expectation. At first the PV input basically went 100% to charging the battery, and the Load started showing up as a negative value, matched by negative Grid values (looks like export?). Then a while after the battery was full (SOC=100%) the inverter went crazy and started pushing out power to the Grid as fast as the battery would deliver, plus whatever it could get from the PV. It shows a massive amount of Load, which simply was not there! Fortunately, it limited the rate of discharge to my setting of 45A (the battery is rated at 100A, so 0.5C would allow for 50A discharge, but I like to play safe).

So - I am perplexed.  Here's the graph for the day. Note that I switched off Limit to Load at about 5:45am, and then I switched it back on at 10:15am.

A further puzzle for me is the behavior after 10:15am. We had good sunshine all day, so why did the system not do a nice consistent charge to full capacity again after returning to the former settings? 

Last note: Something is making me think this is because the CT is misbehaving. Or (heaven forbid) is it installed backward causing the export to non-essentials to run away with itself? It was probably exporting right through to Grid, despite the "Zero-Export" setting. I am remote monitoring, so I'd have to go to the site to verify this.

Here's a custom graph from the inverter, with external CT included (Blue). Perhaps this helps? External CT normally shows as negative here (see before 5:45am, and after 10:15am), but during this period it went positive. What does this mean?

 

Looking forward to receiving an education...

Thank you.

Edited November 9, 20223 yr by Patrick OReilly
added system specs

Looks like the CT coil is the wrong way. 

It should never be negative if you have zero export turned on.

Thank you, Milan.

So, to be clear, I should expect CT to show positive values whenever I'm consuming power from the grid?  And if I manage to produce all the power I need, then CT will report ZERO.  And only if I export (which we don't do in SA) would I see negative values?

Question: Is it OK to physically flip the CT around while the system is running? Or does this require a shut-down?

1 hour ago, Patrick OReilly said:

Thank you, Milan.

So, to be clear, I should expect CT to show positive values whenever I'm consuming power from the grid?  And if I manage to produce all the power I need, then CT will report ZERO.  And only if I export (which we don't do in SA) would I see negative values?

Question: Is it OK to physically flip the CT around while the system is running? Or does this require a shut-down?

Correct. If you have a prepaid meter, some of them let you check your instantaneous usage so the CT measurement should match your meter. 

I am not sure about flipping it while the system is on but maybe change to "Limit to load" (This basically disables the CT) then flip the CT then change back to "Zero Export"

Edited November 9, 20223 yr by Milan188

1 hour ago, Milan188 said:

Correct. If you have a prepaid meter, some of them let you check your instantaneous usage so the CT measurement should match your meter. 

I am not sure about flipping it while the system is on but maybe change to "Limit to load" (This basically disables the CT) then flip the CT then change back to "Zero Export"

Right. Thanks for your feedback Milan!

Hi @Milan188.

So, I have been to the property and did indeed find the CT installed with the arrow pointing out toward the Grid, instead of in toward the Inverter. It is in the correct place - on the live feed BEFORE the non-essential load.  I unclipped the CT, turned it 180 degrees and clipped it back on.

This was at about 6pm. In the graph below you can see numerous negative CT spikes throughout the day prior to this. Afterward I tested by boiling a kettle plugged into a socket that is on the non-essential load. You can see the spike to just over 2kw which is positive instead of negative. and couple more positive spikes later.

I have also noted this morning that when the battery reached the minimum SOC, and I started running internal Load from the Grid, then the Inverter readings for Grid and CT tracked perfectly together, which seems logical.

So - does this now look like correct setup for the CT? If I decide to allow the Inverter to supply to non-essential load, it should be able to manage it correctly now?

Thanks,
Patrick.

4 minutes ago, Patrick OReilly said:

Hi @Milan188.

So, I have been to the property and did indeed find the CT installed with the arrow pointing out toward the Grid, instead of in toward the Inverter. It is in the correct place - on the live feed BEFORE the non-essential load.  I unclipped the CT, turned it 180 degrees and clipped it back on.

This was at about 6pm. In the graph below you can see numerous negative CT spikes throughout the day prior to this. Afterward I tested by boiling a kettle plugged into a socket that is on the non-essential load. You can see the spike to just over 2kw which is positive instead of negative. and couple more positive spikes later.

I have also noted this morning that when the battery reached the minimum SOC, and I started running internal Load from the Grid, then the Inverter readings for Grid and CT tracked perfectly together, which seems logical.

So - does this now look like correct setup for the CT? If I decide to allow the Inverter to supply to non-essential load, it should be able to manage it correctly now?

Thanks,
Patrick.

Yup - looks good now. Now when you push excess to the Non-Ess the CT will block export outside of the system

3 hours ago, Patrick OReilly said:

Hi @Milan188.

So, I have been to the property and did indeed find the CT installed with the arrow pointing out toward the Grid, instead of in toward the Inverter. It is in the correct place - on the live feed BEFORE the non-essential load.  I unclipped the CT, turned it 180 degrees and clipped it back on.

This was at about 6pm. In the graph below you can see numerous negative CT spikes throughout the day prior to this. Afterward I tested by boiling a kettle plugged into a socket that is on the non-essential load. You can see the spike to just over 2kw which is positive instead of negative. and couple more positive spikes later.

I have also noted this morning that when the battery reached the minimum SOC, and I started running internal Load from the Grid, then the Inverter readings for Grid and CT tracked perfectly together, which seems logical.

So - does this now look like correct setup for the CT? If I decide to allow the Inverter to supply to non-essential load, it should be able to manage it correctly now?

Thanks,
Patrick.

Yes it's looking good now. 

You can use the "Zero Export" setting now 

Awesome - thanks @Milan188 and @mzezman.

Solar is not strong at the moment in Gauteng, so I'll be waiting for some nice sunny days and then I'll give that a try.