Jump to content

Sunsynk reduces battery charge power when exporting to grid


Recommended Posts

Posted (edited)

Hi.

My SunSynk 5kW inverter reduces power to the battery when I enable export to grid. I would like it to put the maximum charge into the battery before exporting. 

For example, with export disabled, it is charging the battery with 2kW. When I enable export it reduces that to 0.75W and exports 1.25kW. The state of charge does not make a difference to this pattern so it's not about optimising charge current.

Settings in images attached. You can compare the rate of charge on a day without export and a day with export. 

Short of manually turning on export only after SOC is 100%, is there some logic that throttles battery charging with export that I can bypass with a setting here? Thanks in advance.

FBJ

 

 

 

 

 

No export on top.jpeg

work mode 2.JPG

work mode 1.JPG

Edited by FBJ
Adding comparison of charging rates
  • 2 weeks later...
Posted

Hi again. I have tested all the combinations in scenarios when there is either an excess of available PV or less PV than loads and possible battery charge rate

In all scenarios, the maximum battery charge rate is only achieved when export is disabled.

With export enabled, the closest you can get to the maximum battery charge rate is when you set Priority Battery and have the Timer limit at a higher SOC than your present SOC (e.g. set it at 100%) (A). When there is excess PV, you get almost max battery, then load, then export. As SOC increases (~>50%), the battery charge rate drops off more from the charge rate you would get with export disabled.

untitled image

If it's possible to predict when you will definitely have excess PV and set the timer threshold accordingly, then the closest compromise you can get is (A) and then (C). The risk is (B) when there is low sun, then you get priority battery and import instead of load then battery.

The following sample shows those three modes (where the timer threshold is 80%), assuming export enabled. In all cases battery charge rate would also have been higher if export disabled.

untitled image

untitled image

In summary, I find: in all scenarios, enabling export means that the possible battery charge rate will not be maximised. There is no combination of settings that prioritise load, then max charge rate to battery, then export. Aside from when Priority Battery, and below the Timer Threshold, they will prioritise load, then split battery and export with a logic algorithm that is not clear. I suspect its a simple case of paralleling them with no prioritising. Unless someone can help me find a solution, I would suggest this is surely something that Sunsynk could improve.

Thanks in advance

FBJ

Posted (edited)

Bear in mind that export is seen as part of Load Priority. If you untick Priority Load then battery charge takes preference. It is for this reason that you found charging at a higher rate when you untick Zero Export.

For some users the export of power is more important than supplying the load. Income generating.

It all comes down to what you ask the inverter to do :)

Edited by Scorp007
Posted

Thanks very much for your response, @Scorp007 . I was not aware that export was treated as load by the algorithm. If that is the case then it's unfortunate that there would be no option for a merit order that matches the value to those who have this price structure. In Cape Town, I pay R2.40 per unit and get R1.01 per unit fed back. So the merit order would be:
1) Load: R2.40/kWh for every load unit saved
2) Battery: R2.10/kWh for load after battery efficiency
3) Export: R1.01/kWh for export

However, something still doesn't stack up. If it prioritises load+export over battery in Priority Load, then why doesn't it export to the maximum export limit (up to 4600W in my case) before charging? Instead it exports an arbitrary amount and charges an arbitrary amount.

You can see this in the cases above (C) when Priority Load is selected and when deselected - it goes to load and then some combination of export below maximum allowable export and charge below maximum possible charge.

I'm still not convinced that there's a deliberate prioritising between export and battery in the algorithm and am curious to hear from Sunsynk or be convinced otherwise.

Posted (edited)
4 hours ago, FBJ said:

Thanks very much for your response, @Scorp007 .

I'm still not convinced that there's a deliberate prioritising between export and battery in the algorithm and am curious to hear from Sunsynk or be convinced otherwise.

All I can say is read the training manual. I hope the other users have read the manual.  :) People in the only city that I know of that get paid the same for their export as what they use will be happy with the algorithm as is. Bear in mind settings are not what is gr8 for SA with its problems on the grid.

Other countries make it worth their while to export and don't have the silly basic fee to overcome. Think of us poor people in the North that only get 12c per kWh for export and paying R2.40 for use :)

While you don't want to export you are getting a lot of PV for your load or charging of the battery.

All these factors must be taken into account.

Edited by Scorp007
Posted

Hi @Scorp007. Sorry to hear you only get R0.12/kWh  - that's pretty dismal. I've read the manual backwards and can't see a means to set the merit order I'm looking for - would be grateful if you had a chance to refer me to the section of there is such an explanation. 

Posted
5 hours ago, FBJ said:

Hi @Scorp007. Sorry to hear you only get R0.12/kWh  - that's pretty dismal. I've read the manual backwards and can't see a means to set the merit order I'm looking for - would be grateful if you had a chance to refer me to the section of there is such an explanation. 

I will be sending you a PM will contact details to the 63 page manual. Here is what is mentioned on p14 as far as the priority between bat charging and supplying the load/export.

I don't have a link but I saved it some time ago to have a detail reference. Another problem I found members mention is the reverse connection of the CT. This is clearly documented and an example what the readings will be if reversed.

IMG_20220415_165423.thumb.jpg.3c3bcc4ff0d9bebe01e5076a19cc64be.jpg

 

Posted (edited)

Ya, I have the manuals from here, however they don't give any useful specifics that would help with a merit order of load, battery, export. And they have errors - e.g. this chestnut, where they've jumbled the two settings up.

 

Screenshot_20220416-163720_Adobe Acrobat.jpg

Edited by FBJ
Posted

On my SunSynk 8.8 kW  "System Mode" settings the one setting is "Solar Export Bat Full", this should work. Never bothered to test it though.👍

Posted

@FBJ Wrote "I have tested all the combinations in scenarios" Excellent analysis!
Do you have a CT coil installed or are relying on the internal sensor?

I also noticed something similar / unusual which I suspect is caused by an inverter limit in the DC-to-DC or DC-to-AC circuit or a firmware issue.

All my load is on Essential.
The SunSynk 8k would not use all the Solar (DC) available.

5.5kW Solar DC available - perfectly clear midday.
6.5kW Essential Load

What I observed:
Solar DC 2kW + Battery DC 4.5kW -> Load 6.5kW
What I expected
Solar DC 5.5kW + Battery DC 1kW -> Load 6.5kW

In the image below, the supply switches from Solar to battery when the load (6.5kW) exceeded available solar (5.5kW) - green dotted line.

image.thumb.png.0d3c18905b89eff9f466d69ddaf6e0fc.png

 

Anyone have any ideas why this happens?

Posted
15 hours ago, TimCam said:

On my SunSynk 8.8 kW  "System Mode" settings the one setting is "Solar Export Bat Full", this should work. Never bothered to test it though.👍

I don't seem to have that option or its labelled differently. Might be a firmware difference.

Posted
1 hour ago, system32 said:

@FBJ Wrote "I have tested all the combinations in scenarios" Excellent analysis!
Do you have a CT coil installed or are relying on the internal sensor?

I also noticed something similar / unusual which I suspect is caused by an inverter limit in the DC-to-DC or DC-to-AC circuit or a firmware issue.

All my load is on Essential.
The SunSynk 8k would not use all the Solar (DC) available.

5.5kW Solar DC available - perfectly clear midday.
6.5kW Essential Load

What I observed:
Solar DC 2kW + Battery DC 4.5kW -> Load 6.5kW
What I expected
Solar DC 5.5kW + Battery DC 1kW -> Load 6.5kW

In the image below, the supply switches from Solar to battery when the load (6.5kW) exceeded available solar (5.5kW) - green dotted line.

image.thumb.png.0d3c18905b89eff9f466d69ddaf6e0fc.png

 

Anyone have any ideas why this happens?

Yes, I have the CT.

Not meaning to be facetious, but is it possible that some clouds came by just then? That's the only explanation I can imagine from what I can see.

Posted

@system32

From your graph it is only when your load exceeds the PV that the battery is used your PV somehow about the power that is going to charge the battery. Perhaps place the full graphic of the inverter showing the panels, battery, UPS and grid then you have a 6.5kw load connected. 

 

Posted
53 minutes ago, FBJ said:

Yes, I have the CT.

Not meaning to be facetious, but is it possible that some clouds came by just then? That's the only explanation I can imagine from what I can see.

No clouds - promise.
I have an old tablet with Solar-Assistant live web page in the kitchen, when I saw the issue I went out side - perfect blue sky.
I think some limit in the 8kW was being breached.

Posted (edited)
1 hour ago, Scorp007 said:

@system32

From your graph it is only when your load exceeds the PV that the battery is used your PV somehow about the power that is going to charge the battery. Perhaps place the full graphic of the inverter showing the panels, battery, UPS and grid then you have a 6.5kw load connected. 

 

I've not seen this before as the load is normally quite low 1kW-4kW and then the PV is used.
Below are all the graphs from Solar Assistant from 2022-04-15 11:30:00 to 2022-04-15 13:00:00
image.thumb.png.c9b270a85c355abc927e92ca478d705a.png

image.thumb.png.c3dbed1419a922a82181016ba915858d.png

image.thumb.png.655c301de17f6cabc37339af4d82e11b.png

image.thumb.png.d7d89877a2b629d8b4936241d7103519.png

image.thumb.png.8d5621affd78cc8593eb97480716448b.png

 

Edited by system32
Posted
7 hours ago, system32 said:

@FBJ Wrote "I have tested all the combinations in scenarios" Excellent analysis!
Do you have a CT coil installed or are relying on the internal sensor?

I also noticed something similar / unusual which I suspect is caused by an inverter limit in the DC-to-DC or DC-to-AC circuit or a firmware issue.

All my load is on Essential.
The SunSynk 8k would not use all the Solar (DC) available.

5.5kW Solar DC available - perfectly clear midday.
6.5kW Essential Load

What I observed:
Solar DC 2kW + Battery DC 4.5kW -> Load 6.5kW
What I expected
Solar DC 5.5kW + Battery DC 1kW -> Load 6.5kW

In the image below, the supply switches from Solar to battery when the load (6.5kW) exceeded available solar (5.5kW) - green dotted line.

image.thumb.png.0d3c18905b89eff9f466d69ddaf6e0fc.png

 

Anyone have any ideas why this happens?

Very strange behavior. When solar is insufficient, my SunSynk 8.8 kW assists with grid power for the shortfall, and only uses battery if grid is off. Maybe it is due to a setting in the "System Mode", while using "Timer". I never use the timer during the day.

Posted
22 hours ago, TimCam said:

Very strange behavior. When solar is insufficient, my SunSynk 8.8 kW assists with grid power for the shortfall, and only uses battery if grid is off. Maybe it is due to a setting in the "System Mode", while using "Timer". I never use the timer during the day.

Noticed the issue again today.
I've logged a call with Sunsynk support for some advice.

Posted

The mppt does a scan every now and then to make sure you are still on the max power point. Could it maybe account for the PV output taking a slight dip and needing to fall back on battery power to run the loads? Just a guess

  • 1 month later...
Posted

For those who may be following the original thread on whether the inverter can be programmed for merit order:

  1. Load; then
  2. Battery; then
  3. Export

I have not had a resolution from Sunsynk support to date. I have been referred to the manual, which does not have a resolution and I have had suggestions that do not give this merit order. Since, as I have not had follow-up, it may mean I must infer that there is no solution with this product. 

 

Posted
1 hour ago, FBJ said:

For those who may be following the original thread on whether the inverter can be programmed for merit order:

  1. Load; then
  2. Battery; then
  3. Export

I have not had a resolution from Sunsynk support to date. I have been referred to the manual, which does not have a resolution and I have had suggestions that do not give this merit order. Since, as I have not had follow-up, it may mean I must infer that there is no solution with this product. 

 

Do you have the latest firmware?
I had a prioritization issue which was fixed when I requested the latest firmware.

Posted
3 hours ago, FBJ said:

For those who may be following the original thread on whether the inverter can be programmed for merit order:

  1. Load; then
  2. Battery; then
  3. Export

I have not had a resolution from Sunsynk support to date. I have been referred to the manual, which does not have a resolution and I have had suggestions that do not give this merit order. Since, as I have not had follow-up, it may mean I must infer that there is no solution with this product. 

 

I doubt that you can get an answer to your requirement. The Sunsynk just have 10 times more permutations than just these 3 by using the timers and values of power for what one needs at different times.

These 3 priorities belong to the Axperts accept that the Axpert cannot export.

I belief if one wants to do your own settings and not rely on an installer then one needs to be prepared to do the on line training videos and studying the manuals.

From what I read in the training battery charging and export sits in the same mode. You either export or use no export with CT installed to get maximum battery charge.

May be some combinations still need to be found to add to what you have tried.

  • 2 weeks later...
Posted
On 2022/05/20 at 4:24 PM, system32 said:

Do you have the latest firmware?
I had a prioritization issue which was fixed when I requested the latest firmware.

Yes

  • 1 year later...
Posted

@FBJ Were you ever able to resolve this problem or work out why this is happening. Ive been struggling with the same issue on multiple sites.

Im now dealing with sunsynk support who are also not seemingly sure on why this is happening. Im getting odd type of reasons such as the inverter uses the voltage on the terminals to determine when batteries are full. That does not sound right to me as different batteries have either 15 or 16 cells meaning different voltages. It should be using the SOC from the BMS to determine SOC and therefore when to export.

 

 

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...