An installer fitted a 8kW Sunskyn inverter in December to replace a Mecer 5kW unit that was severely misbehaving

There are 10 PV panels on 2 MPPT strings. 1 has 6 panels, 2 has 4

Battery 1 is connected via a cable (supplied with the inverter) from CAN on the battery to CAN on the inverter

There are 4 x Shoto Box 10 5kW batteries. The batteries are each connected to RS485 ports

The DIP switches were set according to the Shoto book: Bat 1 - 5 & 6 on, bat 2 - 1 on, bat 3 - 2 on, bat 4 - 1 & 2 on

BMS shows voltage, temp, SOC

Unfortunately, the installer died from a stroke in January and the fellow who assisted him knows very little. I did ask another installer but he did not turn up as agreed and was rude

I have some questions:

1 - Sunskyn Connect has never worked well. It shows the Plant Details and the inverter, the wifi device connects to house wifi, the power total but nothing else. Is it meant to offer more details?

2 - The solar battery charging using the Sunskyn is far less than the Mecer. Prior to fitting it, all batteries reached 100% SOC by 14h00. The Sunskyn stops at about 80%

3 - I used to switch off the incoming mains in September until March and run on solar and batteries

4 - Are the DIP switch settings correct? Is there a way to see the SOC and charge cycles of each battery?

Do any if these pictures reveal anything that needs altering. I do have the correct Sunskyn manual

Thank you

1 hour ago, chrisc said:

There are 4 x Shoto Box 10 5kW batteries

Battery type should have 400Ah capacity and 200A charge current. It looks to me as if the highest voltage should be 56.4V.

Ok, increased capacity to 400 a/h

Maximum possible charge current is 185A, so set it to that

Right now, have had full sun and no clouds all day, SOC is 69%

One other question please:

Why does the battery have a - value?

1 minute ago, chrisc said:

Why does the battery have a - value?

The minus sign is an indication that the battery is charging. When this sign disappears, then the battery is discharging.

4 minutes ago, chrisc said:

Ok, increased capacity to 400 a/h

Maximum possible charge current is 185A, so set it to that

If I understand your first post correctly, you have 4 x 5kWh batteries - thus a total capacity of 20kWh (or 400A). I have the same capacity, but believe in limiting the charge and discharge to reasonable limits. You will have a much increased battery life if you could keep the charge/discharge rate to 0.2C (80A), or preferably not more than 0.25C (100A).

2 hours ago, chrisc said:

One more thing - on the System screen above, you need to check the "Use Timer" tickbox, else this time control feature will not work.

Chris, if possible, please give us some more information on the system - e.g. how are the four batteries connected electrically to the inverter? It is quite important to use thick enough battery cabling, and to keep all the cable lengths exactly the same. It's also safer to connect the four batteries to two buss bars (one positive, the other negative) to ensure that there is no imbalance between the individual batteries.

Hopefully, @TaliaB will confirm the critical safety devices (DC isolators, fuses, etc.) needed for a safe system, just so that you can confirm if everything was installed correctly.

If you like, you can send me your email address via PM, and I can then send you some Sunsynk installer videos that are quite helpful to understand your system.

4 hours ago, chrisc said:

2 - The solar battery charging using the Sunskyn is far less than the Mecer. Prior to fitting it, all batteries reached 100% SOC by 14h00. The Sunskyn stops at about 80%

If installed correctly, the Sunsynk will push solar into your non-essential loads. This may mean that your solar is underrated for the house.

4 hours ago, chrisc said:

An installer fitted a 8kW Sunskyn inverter in December to replace a Mecer 5kW unit that was severely misbehaving

There are 10 PV panels on 2 MPPT strings. 1 has 6 panels, 2 has 4

Battery 1 is connected via a cable (supplied with the inverter) from CAN on the battery to CAN on the inverter

There are 4 x Shoto Box 10 5kW batteries. The batteries are each connected to RS485 ports

The DIP switches were set according to the Shoto book: Bat 1 - 5 & 6 on, bat 2 - 1 on, bat 3 - 2 on, bat 4 - 1 & 2 on

BMS shows voltage, temp, SOC

Unfortunately, the installer died from a stroke in January and the fellow who assisted him knows very little. I did ask another installer but he did not turn up as agreed and was rude

I have some questions:

1 - Sunskyn Connect has never worked well. It shows the Plant Details and the inverter, the wifi device connects to house wifi, the power total but nothing else. Is it meant to offer more details?

2 - The solar battery charging using the Sunskyn is far less than the Mecer. Prior to fitting it, all batteries reached 100% SOC by 14h00. The Sunskyn stops at about 80%

3 - I used to switch off the incoming mains in September until March and run on solar and batteries

4 - Are the DIP switch settings correct? Is there a way to see the SOC and charge cycles of each battery?

Do any if these pictures reveal anything that needs altering. I do have the correct Sunskyn manual

Thank you

On the battery setup , the charging amps is set way too low for your massive battery bank, this is what is causing you to lose out on power , i would set the charge current at 100-120A .

Next on the system mode screen tick use timer and set the soc on 40% for all lines . This will make sure you actually use your batteries. Also tick "signal island mode" to make sure it does the N-E bonding if there is no hard bond .

It does not seem like he installer was familiar with this inverter so i would make sure the CT coil placement is correct and also the settings on the second work mode screen so you are feeding back to non essentials if there are any .

Give some pictures from the other work mode screen and the Li BMS screen please.

Also post a graph of both solar stings voltage through a typical day , 4 panels might be too little voltage to keep the MPPT running properly so that could also make you lose power.

Edited February 8Feb 8 by Nexuss

I agree with all the other statements made by Nexuss, except for the following:

1 hour ago, Nexuss said:

On the battery setup , the charging amps is set way too low for your massive battery bank, this is what is causing you to lose out on power , i would set the charge current at 100-120A .

With regards to the one quoted above, I agree that the battery would charge quicker at a higher amperage, but charging current should ideally be matched to the depth of discharge that needs to be "filled up" again whilst the sun is shining. So, lets do the math:

Given the total capacity of the four batteries of 20kWh, let's assume a SOC of 40% (thus 60% DOD), which equals to 20000x0.6 = 12000Wh. Assuming a system loss of 20% whilst charging, one will have to replace 12000x1.2 = 14400Wh to fully charge the battery. Dividing this by the battery voltage (let's call it 52V) one would need to replace 14400/52 = 277Ah. If charging at 0.2C (400A x 0.2 = 80A), the batteries should be fully charged (from 40% SOC to 100% SOC) in 3.5 - 4 hours. Charging at 0.25C (100A) it should only take about 2.8 hours, but is such rapid charging really necessary? Obviously, if the batteries are discharged deeper (not advisable if one wants maximum battery life), then one would either have to up the charging current, or lengthen the charging time.

Here's a typical Sunsynk chart showing a "standard" solar day for my system with a deliberate battery discharge between 04:00 and 05:00 (the pink colour) to create more storage space in my 20kWh batteries, then a charging cycle that starts at 07:00 and ends at 10:30 (the blue), and the normal daily PV yield (green) and load (red) throughout the day, with a second small battery charge in the afternoon. Note that my SOC only drops to about 70%, hence the lower charging amperage used.

Personal opinion. I would just set the charge/discharge amps to the higher value, 185A.

My thinking is, on a normal day your charge rate will in any case be limited by the approx 5kW of installed solar power (panel specs TBC), so the amps will naturally top out at around 100A at mid-day (less baseload) and be generally gentle on the batteries.

But whenever you choose a grid-charge, you might want to replenish the batteries quickly, like in preparing for loadshedding, and then you might not want to take half the day or longer to do the charge when you could do it in 2 hrs. Rough thumbsucks. As long as the charge rate of 0.4C - 0.5C is then still within the manufacturer's recommendation and the installed wiring, etc supports it.

Edited February 8Feb 8 by GreenFields

20 hours ago, chrisc said:

An installer fitted a 8kW Sunskyn inverter in December to replace a Mecer 5kW unit that was severely misbehaving

There are 10 PV panels on 2 MPPT strings. 1 has 6 panels, 2 has 4

Battery 1 is connected via a cable (supplied with the inverter) from CAN on the battery to CAN on the inverter

There are 4 x Shoto Box 10 5kW batteries. The batteries are each connected to RS485 ports

The DIP switches were set according to the Shoto book: Bat 1 - 5 & 6 on, bat 2 - 1 on, bat 3 - 2 on, bat 4 - 1 & 2 on

BMS shows voltage, temp, SOC

Unfortunately, the installer died from a stroke in January and the fellow who assisted him knows very little. I did ask another installer but he did not turn up as agreed and was rude

I have some questions:

1 - Sunskyn Connect has never worked well. It shows the Plant Details and the inverter, the wifi device connects to house wifi, the power total but nothing else. Is it meant to offer more details?

2 - The solar battery charging using the Sunskyn is far less than the Mecer. Prior to fitting it, all batteries reached 100% SOC by 14h00. The Sunskyn stops at about 80%

3 - I used to switch off the incoming mains in September until March and run on solar and batteries

4 - Are the DIP switch settings correct? Is there a way to see the SOC and charge cycles of each battery?

Do any if these pictures reveal anything that needs altering. I do have the correct Sunskyn manual

Thank you

Under battery setup screen the bms communication is not activated on the inverter, tick Activate then check on Li-Bms page if it is communicating, your charge discharge current will be updated from the Bms SOC and SOH will be displayed. See below:

18 minutes ago, TaliaB said:

Under battery setup screen the bms communication is not activated on the inverter, tick Activate then check on Li-Bms page if it is communicating

That is not what the "activate" function does...

"The "Activate" function (often a checkbox) in the battery setup page of a Sunsynk (also stylized as SunSynk) hybrid inverter is primarily used with lithium battery configurations . It helps recover or "wake up" a lithium battery that has become over-discharged. In such cases, the battery's built-in Battery Management System (BMS) shuts down the battery for protection, preventing it from charging or discharging normally .Enabling "Activate" forces the inverter to provide a low-current charge (from solar panels or the grid) to the battery, even when the BMS is in a protected/shutdown state. This slowly reactivates the battery and allows normal operation to resume." From Sunsynk website.

Thank you for all the replies

Yes, there is a battery isolator
I have adjusted the charge rate to 100 amps
Ticket the "Activate" block on Battery Setup
AC is off most of the time from October to March. There are only 2 of us in the house and the 200L geyser has a separate solar system

How about the DIP switch settings on the 4 batteries. Are they correct?
I agree the installer was not that experienced. You only find that out when he starts getting a bit unsure of what to do. He got the power up sequence incorrect, but when he left I did it myself to get it working. As I told him, its useful to read and understand the manual

Here is the BMS screen and Flow Chart. Do you spot anything amiss?

9 minutes ago, chrisc said:

Thank you for all the replies

Yes, there is a battery isolator
I have adjusted the charge rate to 100 amps
Ticket the "Activate" block on Battery Setup
AC is off most of the time from October to March. There are only 2 of us in the house and the 200L geyser has a separate solar system

How about the DIP switch settings on the 4 batteries. Are they correct?
I agree the installer was not that experienced. You only find that out when he starts getting a bit unsure of what to do. He got the power up sequence incorrect, but when he left I did it myself to get it working. As I told him, its useful to read and understand the manual

Here is the BMS screen and Flow Chart. Do you spot anything amiss?

BMS comms looks good and is working fine , all 4 batteries are there if you look at the discharge current limit ..Your charge voltage is high but i dont think you can do anything about that , i am unfamiliar with your batteries/firmware, might look into using voltage mode instead of BMS comms. Regarding the dip switch settings ,refer to the battery manual.

The next screen shows that you have no non essential ? do you have your entire house connected on the load/ups side of the inverter ?

Edited February 9Feb 9 by Nexuss

8 minutes ago, chrisc said:

Thank you for all the replies

Yes, there is a battery isolator
I have adjusted the charge rate to 100 amps
Ticket the "Activate" block on Battery Setup
AC is off most of the time from October to March. There are only 2 of us in the house and the 200L geyser has a separate solar system

How about the DIP switch settings on the 4 batteries. Are they correct?
I agree the installer was not that experienced. You only find that out when he starts getting a bit unsure of what to do. He got the power up sequence incorrect, but when he left I did it myself to get it working. As I told him, its useful to read and understand the manual

Here is the BMS screen and Flow Chart. Do you spot anything amiss?

The CT coil is not on the system flow diagram you need to investigate why it is not showing up.

Wouldn't be the first time a SunSynk/Deye Installer doesn't install the CT coil. I once came across this during an inspection. Customer went and fetched the Inverter's original box it came in, but alas, the CT coil was missing.

6 hours ago, chrisc said:

I have adjusted the charge rate to 100 amps

Did you get the battery to 100%?

Show the System Mode > System 2 screen.

The CT coil does not display as there is no AC to the inverter. The actual coil is clamped around the feed from the main switch which goes to the CB feeding the inverter and the white and black leads are in terminals 5 and 6

The batteries got to 71% today

However, there has been a major power cut in Cape Town s/suburbs since 11h00 this morning due to last night's storm so not much I can do. All the neighbours are sitting in the dark

I'll look again tomorrow

Forgot:

The entire house (except for the geyser which has own solar system) is connected to the load

I also ticket "Zero export"

Here are some more images

I cannot see the CT Coil symbol. Perhaps it is incorrectly placed. In the DB the main switch is a 3-pole unit. The output of phase 1 connects directly to the AC input of the inverter. Where it comes out of the main switch, the cable wraps around the CT coil. The arrow points towards the inverter

Please point out any irregularities re these pictures

1 hour ago, chrisc said:

Here are some more images

I cannot see the CT Coil symbol. Perhaps it is incorrectly placed. In the DB the main switch is a 3-pole unit. The output of phase 1 connects directly to the AC input of the inverter. Where it comes out of the main switch, the cable wraps around the CT coil. The arrow points towards the inverter

Please point out any irregularities re these pictures

You wont see the CT coil in the flow diagram when "limit to load" is ticked, Since you have everything on the load side of the inverter you can leave it as is. Only thing i would change is the grid tricle feed to 0 watts and on the work mode screen set the SOC much lower . As it is now you will only use 20% of the battery, unless there is a grid failure/loadshedding. I would set them all at 40% as previously mentioned. I have mine set to gradually go down to 10% to get maximum battery utilization. Also tick "Priority load" so the load is priority above battery (battery wil charge with the solar thats left after servicing the load) . Currently it will charge battery first meaning you will use grid till you reach the set SOC in work mode timer.

Edited February 10Feb 10 by Nexuss

12 hours ago, chrisc said:

Forgot:

The entire house (except for the geyser which has own solar system) is connected to the load

I also ticket "Zero export"

If this geyser still uses grid /like in winter it would be useful to untick "limit to load" to be able to supply it with solar power as well. Also just so you know the "grid signal" and "grid charge" functions on the battery setup page needs to be ticked for grid charging to work if you ever want to do that(in work mode you set the time slots which you want grid charging for). I would recommend ticking both so the battery has access to grid charging very low SOC like below 5% the BMS can then request a force charge automatically if that ever happens.

Edited February 10Feb 10 by Nexuss

1 hour ago, chrisc said:

Here are some more images

I cannot see the CT Coil symbol. Perhaps it is incorrectly placed. In the DB the main switch is a 3-pole unit. The output of phase 1 connects directly to the AC input of the inverter. Where it comes out of the main switch, the cable wraps around the CT coil. The arrow points towards the inverter

Please point out any irregularities re these pictures

Just check if there are 2 thin wires on terminals 3 and 4 or 5 and 6 in the terminal box. If not there no CT is wired in no matter where the CT is.

Edited February 10Feb 10 by Scorp007

15 minutes ago, Scorp007 said:

Just check if there are 2 thin wires on terminals 3 and 4 or 5 and 6 in the terminal box. If not there no CT is wired in no matter where the CT is.

12 hours ago, chrisc said:

The actual coil is clamped around the feed from the main switch which goes to the CB feeding the inverter and the white and black leads are in terminals 5 and 6

Seems like that was already confirmed.

Edited February 10Feb 10 by Nexuss

30 minutes ago, Nexuss said:

Seems like that was already confirmed.

Thanks for pointing it out. Quilty as charged as I only looked at this morning's posts. 😅