Deye - "Zero Export To CT" Reduces Power & Load Values

[QB87]

Hi Everyone,

My solar setup is: 12x 550w solar panels, 2 x 5kw Deye hybrid inverters in parallel and a 1 x 10kWh Life Po4 battery.

The system was installed about two months ago and I'm using Solar Assistant to monitor the system. I have a CT clamp installed (Let's assume it is installed correctly).

Recently I changed the "System Work Mode" setting on the inverter from "Zero Export To Load" to "Zero Export To CT" so that the system can provide power to non-essential loads. After enabling "Zero Export To CT" I noticed the "Load", "Solar PV" and "Grid" power values on the Solar Assistant dashboard dropped to much lower values compared to when I had the "Zero Export To Load" option enabled. I shared some graphs below for more information.

I have a couple of questions:

1. The values displayed by Solar Assistant, do those values show how much power is consumed or how much power is generated or what exactly do they show? In orther words, when I look at the graph showing Load, Solar PV and Grid power values, how should I interpret the graph?
2. Why did the Load, Grid and PV Power values drop lower when I enabled "Zero Export To CT"?
3. On Solar Assistant I can see the "Essential Load" graph has positive y-axis values but the "Non-Essential" load graph has negative values. When "Zero Export To CT" is enabled, it looks like Solar Assistant calculates the overall load as "Non-Essential"  + "Essential" loads. Since the "Non-Essential" load values are much higher, Solar Assistant displays the overall load as a negative value. So my question is, why is the "Non-Essential" load values negative? Why not take the absolute value of both Essential and Non-Essential values and add them together. That way you can see how much total load the system is handling.

 

 

Solar Assistant graph showing Load, Grid and PV Power when "Zero Export To Load" was enabled

Notice the Y-Axis values range from 0 to 5K.

 

Solar Assistant graph showing Load, Grid and PV Power when "Zero Export To CT" was enabled

"Zero Export To CT" was enabled on 2023-04-09 at 17:21. You can see the values on the left hand side the vertical line, at 17:21, is much higher than the value on the right hand side. Why did the values reduce when I enabled "Zero Export To CT"?

To get a better view of the Y-Axis values after "Zero Export To CT" was enabled, I zoomed in on a smaller time window.

Also note in the below graphs the positive values for "Load Power Essential" and negative values for "Load power non-essential" after enabling "Zero Export To CT".

 

Finally, to double check that Solar Assistant values and the Inverter values lines up, I've taken a screenshot and picture of both at the same time.

 

 

 

 

 

 

 

 

[Charl Joubert]

Ah I know exactly what you're saying.  I'm having the same issue with mine where my CTs are likely in the wrong position.  In my instance they don't actually need to be connected and it seems to be forcing the "Zero Export to CT" option.  It keeps jumping back from "Zero Export to Load".  I'm going to disconnect my CTs and report back to see if my values are corrected.

I like to think of myself as a budding expert so let me try to answer some of your questions (and likely illicit some corrections):

1. Your three main ones, Load Power, Grid Power, and PV power can be read as:
   1. Load Power - How much your inverter is giving out to your load.  Or another way to put it is how much your house is pulling.
   2. Grid Power - How much Eskom is giving to compliment the Battery and PV to supply the Load
   3. PV Power - How much your PV is supplying to make up the load.  Not how much the PV can potentially give out.  For instance mine was just a few minutes ago generating 14.2kW to charge the battery and the moment it 100% it dropped down to match the load.
2. I think this is due to incorrect installation of the CT.  In my case I'm going to remove them since I'm not planning on feeding back AND ALL of my load is on the main "backup" feed of the inverter.  As far as I can tell the little CTs need to be connected BEFORE the main DB on the incomming main grid line.  I'd need about 100m of CT cable but that's besides the point.
3. Ja this is my suspicion as well.  The CTs aren't installed correctly.  They may be backwards OR in the wrong spot.  As you can see here I'm also getting negative values with the CT function enabled:

I'm not sure how your backup solution is set up but in my case I don't think I need the CTs.  I'm going to disconnect them and report back.

On these inverters you have three "sources"; your main backup, the non-essentials, and the "smart" load.  The non-essentials are what needs the CTs connected properly.

Another curious thing is that when I enable the Solar Sell option the numbers jump back to where they're supposed to be.  I set the sell to 5w because I don't actually want to sell.  But this for some reason makes my solar dip out for about a minute every ten minutes roughly and grid picks up the slack.  Not ideal.

UPDATE:  So I pulled my CTs loose and it confused the system.  It had no idea what was going on.  Running a single inverter not in Parallel it let me set "Zero Export to Load" and the numbers made sense.  Putting them both into Parallel again and the setting changed back to "Zero Export to CT".  So I've left it, put the CTs back.  I've contacted the Chinese Deye support line again and they're roping in an engineer who should respond tomorrow.  I hope it can shed light on your problem as well.

Just a note on Solar Assistant, the "Auxiliary load power" graph is the smart load.  The non-essentials are 100% what use the CTs.  I see on my graph there was a flutter in non-essential when I fiddled.  I'll update again tomorrow.

So glad it's not just me having this issue!

Edited April 19, 2023 by Charl Joubert

[Charl Joubert]

Deye downgraded my software by one version for me because the latest that I was on would default to Zero Export to CT.  I was then able to select Zero Export to Load and my weird negative values went away.  I can only imagine that my CTs, besides being uneccessary, were installed incorrectly throwing the values off.

I hope that can point you in the right direction.

[Patrick OReilly]

Hi all.

I run a 5kw Sunsynk. Essentially the same as the Deye, but slightly different software. With Sunsynk I use their software management via the SunsynkConnect App, or their web site, so I’m not familiar with solarman.

Anyway, my reason for responding here is because my original installation was incorrect in that the CT was installed in the right place, but in the wrong direction. That messed with the behaviour when running “zero export”. By simply flipping the CT around the behaviour was corrected.

Lesson: The correct installation of the CT is vital if you Intend to support any loads in the non-essential load part of the system.

Definition: The non-essential load is all those appliances that are connected to the DB, between the CT and the inverter. Usually it would be your geyser(s), oven, and similar high-load items. This is why correct location of the CT matters - it defines the outer boundary of your system, and thus of the non-essential load portion of the system!

There are two important details for the correct installation of the CT:

1) Location: the CT should be reading the flow of power from the Grid into your overall system. So it should be installed on the main grid feed, at your grid meter, OR at your DB where the feed from the meter enters the DB. At this point the CT is able to measure any movement of power between the grid and your system. This data is needed for the inverter to operate correctly.

2) Direction: the CT measurement is directional, and the direction of flow is important information. 1kw import from the grid is NOT the same thing as 1kw export to the grid - obviously. For the CT to read this correctly it must be installed facing the correct way. In the case of the Sunsynk, the CT has an Arrow visibly displayed on its exterior, and when installed this arrow must point TOWARD THE INVERTER.

 

Notes about the settings:

Again, the software on the Sunsynk uses slightly different labels compared to the Deye, but I’m sure you will follow:

Limit to Load: this tells the inverter to support essential load ONLY. No power will be sent to the non-essential load. In this mode, the CT does not really serve any useful purpose.

Zero Export: this tells the inverter to support both essential and non-essential load, but NOT to export anything to the grid. In this mode you can see why we need the CT - the inverter uses the CT to measure flow “at the meter”, and attempts to keep this equal to zero. Nothing in, nothing out.

Selling First: this tells the inverter to export all excess power to the grid. Unless you have a selling agreement with your metro, you don’t want to do this, and you may land yourself in trouble if you do. So as far as I know: in South Africa, don’t use this setting.

 

A final note about how the inverter supports the non-essential load:

My installer tried to give me technical explanations about how the inverter “pushes back against the grid” to feed the non-essential load, manipulating frequency, or voltage, or whatever it does. That is beyond me, since I’m not an electrically trained person. But the way I picture it in my mind is like this:

There are two sources of power into the non-essential load : 1) the grid (in through the CT), 2) the inverter.

Let’s say your geyser kicks in to heat the water, and it pulls power - say 3kw. This will naturally come from the grid, because the inverter is not usually exporting power throughout its input connection. Now immediately the CT informs the inverter that there is 3kw being imported from the grid. The inverter assesses its situation, and since it is the middle of a sunny day it determines that it has excess power (PV production is greater than the load), so the inverter starts to export - let’s say 2kw of PV production to the non-essential load circuit. The CT now reports only 1kw import from grid. The inverter may then decided to also take stored power from the battery and use that. Since the CT is measuring a deficit of only 1kw, the inverter will draw from the battery at only 1kw, exporting that to non-essential load. So within milliseconds the geyser is actually being powered by some PV, some battery, and zero from the grid. Awesome!

Of course, the inverter assesses the situation and adjusts according to your rules about priority, the actual PV production at the time, the battery SoC, the essential load in the rest of the house, etc. Any shortfall will then be filed by the Grid.

I hope this helps!

[GreenFields]

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Edited April 23, 2023 by GreenFields
Content Deleted

[Frankista]

Hello. I have another issue here: 

Regarding the TOU I am trying to have the following scenario: between 9 pm till 5 am if battery goes lower than 25% then charge from the grid. During the day, don’t use the grid at all. 

I have therefor enabled the following settings (see images) Then I noticed the following: 

Although the SOC was between 25% and 30% and the time was 17:10 the grid was still getting used and the battery was still getting charged by the grid. 

I did as well another experiment: 
Time was 17:30. SOC was 76%. Grid charge was unchecked between 17:00 and 21:00 and battery settings was 80%. The grid was charging the battery. As soon as I set the battery in TOU to 50% grid stopped getting used and battery started discharge by providing power to the load. 

Is that normal? Why is the battery getting charged by the grid although the “grid charge” time slot is unchecked?

[mzezman]

Can you share the actual time of use screen so that we can see how it's setup? 

[Frankista]

Just now, mzezman said:

Can you share the actual time of use screen so that we can see how it's setup? 

 

[Frankista]

Just now, Frankista said:

 

Now I set it up like this as my battery levels are at 65% so the grid does not get used. However as soon as I change it to more than the current SOC, although the grid charge is is unchecked, the power flows from the grid to the batteries and the load!!!

[mzezman]

Untick grid peak shaving

Change your first time to start at 00:00 not 01:00

[Frankista]

1 minute ago, mzezman said:

Untick grid peak shaving

Change your first time to start at 00:00 not 01:00

Unchecking Grid Peak Shaving will solve the issue? In other terms the grid will stop charging the batteries? 

[mzezman]

When i had it selected it cause all sorts of issues for me - unselecting it made them go away. We also dont use grid peak shaving in SA as we do not have different rates for different times to use the grid

[Kilowatt Power]

On 2023/04/23 at 1:28 AM, Patrick OReilly said:

The inverter may then decided to also take stored power from the battery and use that. Since the CT is measuring a deficit of only 1kw, the inverter will draw from the battery at only 1kw, exporting that to non-essential load. So within milliseconds the geyser is actually being powered by some PV, some battery, and zero from the grid. Awesome!

I think battery power can only flow to the load (UPS) and gen port (smart load) but NOT to non-essential loads on the grid input. On the other hand, power from solar can flow to all three ports (load, gen, grid). I stand to be corrected. 

EDIT: It's possible to set up a Deye with Time-of-Use to export surplus battery power anywhere

Edited May 31, 2023 by Kilowatt Power
Correction

[Kalahari Cruiser]

If my time of use SOC setting at night is < than the actual SOC (i.e. "spare battery charge available), then non-essentials are running off my battery, not grid (albeit gris is present). I was a bit surprised by this - already enquired elsewhere today. Basic setting is "limited to home" rather than just "limit to load only". 

[GreenFields]

16 minutes ago, Kilowatt Power said:

I think battery power can only flow to the load (UPS) and gen port (smart load) but NOT to non-essential loads on the grid input. On the other hand, power from solar can flow to all three ports (load, gen, grid). I stand to be corrected. 

It's possible to set up a Deye with Time-of-Use to export surplus battery power anywhere, to the load port (Zero Export to Load), or to the grid port up to the CT coil (Zero Export to CT), or even to the Eskom grid beyond the CT coil (Selling First). Whatever they call the settings on the Sunsynk, I suppose there will be equivalent functions.

[Kilowatt Power]

2 hours ago, GreenFields said:

It's possible to set up a Deye with Time-of-Use to export surplus battery power anywhere

I stand corrected. Thanks. My understanding was very different

@Kalahari Cruiser has raised the same issue with SunSynk here

[Patrick OReilly]

3 hours ago, GreenFields said:

It's possible to set up a Deye with Time-of-Use to export surplus battery power anywhere, to the load port (Zero Export to Load), or to the grid port up to the CT coil (Zero Export to CT), or even to the Eskom grid beyond the CT coil (Selling First). Whatever they call the settings on the Sunsynk, I suppose there will be equivalent functions.

Yup. I can do the same with timer settings on the Sunsynk.

 If you want to use battery for essential load only, you must set “zero export” and “limit to load”.

if you want to use battery for non-essential too, then set “zero export”, but do NOT set “limit to load”.

 And all of the above are subject to the minimum SoC that is set in your timer. So even when you allow battery to be used for non essential load, it will stop doing so when your minimum SoC is reached. This allows you to preserve capacity for load shedding.

Edit: these rules apply very similarly to the PV production when the Sun is shining. If the battery is above minimum SoC, PV production will be used first for essential load, then non-essential load, then to top up the battery. Often it is doing all three simultaneously.

Edited May 31, 2023 by Patrick OReilly
Added note re PV production

[ZaydS]

1 hour ago, Patrick OReilly said:

If you want to use battery for essential load only, you must set “zero export” and “limit to load”.

Thanks. However, the issue I have with this is that “non-essentials” use is not shown. Under-reads grid use then. 

[Patrick OReilly]

16 hours ago, ZaydS said:

Thanks. However, the issue I have with this is that “non-essentials” use is not shown. Under-reads grid use then. 

No. I found a way.

First, when you are allowing the inverter to send power out to non-essential load, then the GRID reading is equal to what the CT reads. In other words it should match what your GRID meter is reading.
Second, when you are allowing the inverter to send power out to non-essential load, then the LOAD reading INCLUDES all consumption (LOAD and export through the GRID port).

Now, since all load is in one number, the frustrating part is to answer: "How much load is essential load, and how much is non-essential?". 

So I found after much experimentation that in the custom graph for the Inverter there is a value called "P-L1" which reveals the "Load" (kw) passing through the Inverter's grid port. This will show positive values when grid power is flowing INTO the inverter, and will show negative values when the inverter is exporting power to the non-essential load.

Here's my graph for this morning - look carefully at the period 10-11am. My geyser kicked in (non-essential), and you can see that PV and Battery power were blended by the inverter to EXPORT to the geyser during that period (P-L1 goes negative). Apart from a short spike in load about 10:35am, the GRID (at the CT) stayed on zero while the inverter supplied the geyser. During that spike you can see that the export also reduced, indicating that the load spike was caused by something inside (essential load), maybe a kettle or something.

Also note the small spike about 5am. Battery was on minimum SoC, so the load, grid and P-L1 were all tracking together. When the battery needed a little charge from grid, you can see battery goes negative, but this time P-L1 is positive (with grid), indicating IMPORT through the CT and through the inverter grid port.

For those running "Limit to load", and you want to know how much the nomn-essentials are taking from the Grid - look at the "P-External-CT-Total" setting (disabled in my image above). this will show import from the grid through the CT, while the "P-grid" in that mode will only show what passes through the Inverter's grid port.
 
I hope this helps...

 

Edited June 1, 2023 by Patrick OReilly

[ZaydS]

@Patrick OReillyThank you. Let me play around with the setting tonight. 

[Kilowatt Power]

23 hours ago, Patrick OReilly said:

Edit: these rules apply very similarly to the PV production when the Sun is shining. If the battery is above minimum SoC, PV production will be used first for essential load, then non-essential load, then to top up the battery. Often it is doing all three simultaneously.

Isn't the PV power source priority not dictated by the "Energy Pattern" setting in System Work Mode menu i.e. Batt First or Load First?

[Patrick OReilly]

19 hours ago, Kilowatt Power said:

Isn't the PV power source priority not dictated by the "Energy Pattern" setting in System Work Mode menu i.e. Batt First or Load First?

You are quite right - while the battery SoC is below your configured minimum. In this case PV goes first to battery, then essential load, then non-essential.

The sequence I mentioned previously is when battery SoC is above the configured minimum.

In my case my minimum SoC is usually at 40% (for load shedding protection), so most of the time the inverter is operating with the battery level above what is required, and so it will feed load before it charges battery.

Edited June 2, 2023 by Patrick OReilly
Getting my facts straight 😊

[PowerUser]

On 2023/05/31 at 2:50 PM, Kalahari Cruiser said:

If my time of use SOC setting at night is < than the actual SOC (i.e. "spare battery charge available), then non-essentials are running off my battery, not grid (albeit gris is present). I was a bit surprised by this - already enquired elsewhere today. Basic setting is "limited to home" rather than just "limit to load only". 

I was quite surprised to find that out as well. Is there anyway to prevent the non-essentials running off the the battery at night?

The Deye inverters have the setting "Zero Export to CT", which I believe achieves that. Anyone been able to find the equivalent combination of settings on Sunsynk? 

Edited June 26, 2023 by PowerUser

[Nexuss]

24 minutes ago, PowerUser said:

I was quite surprised to find that out as well. Is there anyway to prevent the non-essentials running off the the battery at night?

The Deye inverters have the setting "Zero Export to CT", which I believe achieves that. Anyone been able to find the equivalent combination of settings on Sunsynk? 

The easiest way i have found is to just limit the battery power in the system work mode for the particular time. I have mine set to 2000w for the evening so it cant deplete the battery as fast when using the oven or geyser.

[PowerUser]

8 minutes ago, Nexuss said:

The easiest way i have found is to just limit the battery power in the system work mode for the particular time. I have mine set to 2000w for the evening so it cant deplete the battery as fast when using the oven or geyser.

Thank you @Nexuss! I was also thinking of maybe playing with the power settings but that still won't prevent using the battery for the non-essentials completely. Thought, there is another way to achieve it, like the Deye setting. 

What if I have loadshedding and I want to use more than 2000W during that time on the Load side? Isn't limiting the power going to prevent that?

Edited June 26, 2023 by PowerUser