Thanks, appreciate it.

On 2020/09/27 at 11:07 AM, Bloubul7 said:

I used a 60a solid state relay from Communica.  Might be a little overkill but should last

https://www.communica.co.za/products/ksi600a60-l

"Solid state relays" do not provide electrical isolation.  When the MOSFETs on the solid state relay fails, it'll fail short circuit.  Mechanical relays don't have this problem.  You really should not be using that relay.

EDIT: Also it looks like your are connecting the relay using a low voltage circuit?  If that is the case, you've effectively removed the isolation from the low voltage circuit.  A very big no-no.  Anything connected to that low voltage circuit (including network cables) can become live.

Edited September 29, 20205 yr by Gnome

12 minutes ago, Gnome said:

"Solid state relays" do not provide electrical isolation.  When the MOSFETs on the solid state relay fails, it'll fail short circuit.  Mechanical relays don't have this problem.  You really should not be using that relay.

EDIT: Also it looks like your are connecting the relay using a low voltage circuit?  If that is the case, you've effectively removed the isolation from the low voltage circuit.  A very big no-no.  Anything connected to that low voltage circuit (including network cables) can become live.

Thanks,

Will replaced it with a mechanical relay.  It is driven by 220V, the inverter provides a 5 amp 220v islanding switch

3 minutes ago, Bloubul7 said:

Thanks,

Will replaced it with a mechanical relay.  It is driven by 220V, the inverter provides a 5 amp 220v islanding switch

Actually I stand to be corrected:  They internally do use opto-isolator to create isolation: https://www.electronics-tutorials.ws/power/solid-state-relay.html

Just verify in the specification of the relay you bought that it does actually isolate.

54 minutes ago, Gnome said:

Actually I stand to be corrected:  They internally do use opto-isolator to create isolation: https://www.electronics-tutorials.ws/power/solid-state-relay.html

Just verify in the specification of the relay you bought that it does actually isolate.

Thanks, yes they are Opto-isolated

2 hours ago, Gnome said:

"Solid state relays" do not provide electrical isolation.  When the MOSFETs on the solid state relay fails, it'll fail short circuit.  Mechanical relays don't have this problem.  You really should not be using that relay.

I think you may be confusing failure modes... Solid state relays are all isolated, and pretty much only a lightning strike could break down the control to load isolation.

The main safety drawback of SSRs is that the primary failure mode is fail-closed - i.e. if the output fails, it fails in such a way that it carries on conducting.  Mechanical relays can fail closed, but it is extremely rare (something like 1:10^7 for typical relays) - if they fail, they usually fail open - i.e. load disconnected, which is generally a much safer failure mode.

14 hours ago, JustinSchoeman said:

I think you may be confusing failure modes... Solid state relays are all isolated

To be honest with you, I figured from first principles.  Only after did I go read more about it.  I knew that solid state relays were just MOSFETs.  And MOSFETs always fail short-circuit.  However the opto-isolators is pretty decent isolation.  The reason I thought this is because you don't typically expect a relay to consume current on the switching side, only the coil side.  Bit of a drawback with using them I guess.

14 hours ago, JustinSchoeman said:

only a lightning strike could break down the control to load isolation.

Most opto-isolators are rated roughly 4kV, so it doesn't take *that* much to break the barrier (lightning tests typically start at 200kV up to 1MV).  In terms of break-down voltage it is much easier to get higher kV ratings using opto-isolators than relays anyway.  Isolation is more about failure mode than breakdown voltage.

Edited September 30, 20205 yr by Gnome

Anyone with more than 8kwp of panels and the sunsynk 8kw inverter? 

Yesterday I had my first 50kwh of pv production and the display on the inverter seems to only record 50kwh and stops counting pv production beyond this. 

Today looks like another 51kwh solar day and the inverter stopped recording pv production. 

Edited October 12, 20205 yr by Achmat

Hi Achmat

I do record more that 50kw a few times when able to use all the power.

have 8.6kw of panels.

36 minutes ago, Werner67 said:

Hi Achmat

I do record more that 50kw a few times when able to use all the power.

have 8.6kw of panels.

Sunsynk support updated my device on Friday so now the inverter shows the full pv production. 

Seconds pic was before the update. 

Edited October 18, 20205 yr by Achmat

Nice to have something to "do" with all your production. 😉

Hi all

anyone have the last mcu and hmi firmware files for the 8k?

thanks

Hi Guys

Many different topics discussed on this thread and very interesting.

The manual however does not state the rating of the relay required but just that the ATS pins should be connected to the relay.

So why would you need a 40Amp relay if there is going to be no (or minimal) current flowing through the relay - i.e. you don't expect to have 40 amps flowing between N and E? If I understand the function of the neutral - earth bond correctly, this bond is required in order to give the RCD/EL breaker the ability to detect if there is a fault and accordingly, any such variance detected (less than 30mA if I understood it right) will cause the RCD to trip and "break" the current that is being leaked?

Hope I explained this correctly.

 

As a side note, we should convert the latest copy of the PDF manual and make some track changes with all the learnings/additional Q&A and fix up some of the obvious grammar and other errors. Should we start a thread for this?

 

Sunsynk 8kw MPPT is now rated at 2 x 22A. Up from 2 x 18A.

Anyone with the newest units who can confirm the label on actual inverter? 

Hi @Johann1982, I have read your posts with great interest. I have just had Sunsynk 8.8KW + 5.6kw PV + 7.4kW Li installed. My installer has used the N.E. output for most of my heavy loads, but this means I cannot use them during load shedding (not explained).

I would like to move these loads to the Aux output, so that they can be managed on SOC, but am anxious to do this before I understand the problems and would hugely appreciate your advice on this.

If latest version installed, is it still essential to have the relay to bond Neutral/Earth?

Do you know what the capacity limit is on this aux output when grid is on? Obviously in load shedding it would be limited to inverter total capacity, but if grid is available, I see a max "bypass" rating of 90A in manual.

Installer is hesitant to do this, but I think it takes advantage of the Sunsynk design and think it should be done this way.

Look forward to hearing from you.

41 minutes ago, Craig1970 said:

Hi @Johann1982, I have read your posts with great interest. I have just had Sunsynk 8.8KW + 5.6kw PV + 7.4kW Li installed. My installer has used the N.E. output for most of my heavy loads, but this means I cannot use them during load shedding (not explained).

I would like to move these loads to the Aux output, so that they can be managed on SOC, but am anxious to do this before I understand the problems and would hugely appreciate your advice on this.

If latest version installed, is it still essential to have the relay to bond Neutral/Earth?

Do you know what the capacity limit is on this aux output when grid is on? Obviously in load shedding it would be limited to inverter total capacity, but if grid is available, I see a max "bypass" rating of 90A in manual.

Installer is hesitant to do this, but I think it takes advantage of the Sunsynk design and think it should be done this way.

Look forward to hearing from you.

What are your normal loads like. 

The 8kw should be able to handle most household loads. 

I have my whole house connected to the inverter including a 4kw geyser and 3 aircons. Obviously I will not run everything during load shedding at night but during it handles everything. 

My installer also didn't know the sunsynk as he normally installed simple axpert type backup systems. Unless your loads are regularly over 8kw I would either put everything directly on the load or split the higher loads to aux so af not to accidently run them during low pv and load shedding. 

Edit 

Use this diagram to show him. You can have no loads before the inverter. 

Edited February 11, 20215 yr by Achmat
Connection diagram added

Hi @Achmat, yes, I would like to split the loads. My issue is I would like to understand the limitations on this circuit are in Grid and Off-Grid mode rather than trial and error. There is no clear info on this in any manual.

4 minutes ago, Craig1970 said:

Hi @Achmat, yes, I would like to split the loads. My issue is I would like to understand the limitations on this circuit are in Grid and Off-Grid mode rather than trial and error. There is no clear info on this in any manual.

If the grid is available, the combined load on the aux and load connection will be 90A, 8kw from batteries and/or pv with the balance from the grid. 

If the grid is down, the aux and the load output will share the 8kw that the batteries and solar can provide. You can then set at what SOC the aux should stop. 

 

Thanks Achmat this is the way I would interpret it too, but my installer is suspect as it does not read clearly in any docs/explanation. In your experience is the neutral/earth relay always neccessary, or only if major imbalance. Thx for assistance 

On 2021/02/10 at 11:00 AM, Achmat said:

Sunsynk 8kw MPPT is now rated at 2 x 22A. Up from 2 x 18A.

Anyone with the newest units who can confirm the label on actual inverter? 

Hi Achmat, mine was installed this week in Cpt. The label still shows 18+18.

8 hours ago, Craig1970 said:

Thanks Achmat this is the way I would interpret it too, but my installer is suspect as it does not read clearly in any docs/explanation. In your experience is the neutral/earth relay always neccessary, or only if major imbalance. Thx for assistance 

I don't have the neutral earth bond relay. Everything I've read indicates that it's not compulsory and only needed if you have a floating neutral. My whole house is on the inverter which I think eliminates some of the need for the earth bond. 

8 hours ago, Craig1970 said:

Hi Achmat, mine was installed this week in Cpt. The label still shows 18+18.

I'm in Somerset West. 

Your label has more information than mine but our model numbers are the same. Mine was installed in August 2020. 

23 minutes ago, Achmat said:

I don't have the neutral earth bond relay. Everything I've read indicates that it's not compulsory and only needed if you have a floating neutral. My whole house is on the inverter which I think eliminates some of the need for the earth bond. 

Thanks again for your valued input. Are you successfully using the Aux circuit for your heavy (non UPS) loads, and then able to manage them according to battery SOC?

Last question there is a Solar W field on the Aux setup screen, do you know what this setting does - again there is little/no information in help/O&M.

I really want to make full use of the capabilities of this inverter so that heavy load circuits can be connected while load shedding for partial use, but protecting the batteries from being drained too far.  

17 minutes ago, Craig1970 said:

Thanks again for your valued input. Are you successfully using the Aux circuit for your heavy (non UPS) loads, and then able to manage them according to battery SOC?

Last question there is a Solar W field on the Aux setup screen, do you know what this setting does - again there is little/no information in help/O&M.

I really want to make full use of the capabilities of this inverter so that heavy load circuits can be connected while load shedding for partial use, but protecting the batteries from being drained too far.  

I had my aircons and geyser on the aux initially but at the time their was a software issue that caused the Aux to randomly disconnect and reconnect. I moved them to the normal load output but they've since fixed the software issue and there is now an option for the aux to remain connected if the grid is available. I just haven't had time to move the aircons and geyser back to the aux. I am also considering to use the aux for a generator, wind turbine or micro inverter. I could manage the aux loads using the battery SOC. 

The W on the aux screen as far as I recall is a limiter of how much power you want to send to the aux load from solar. So if you currently generating 6kw and you set this to 2 000w, then it will only send up to 2kw to the aux load. 

 

That is exactly how it's meant to be used. The sunsynk had really delivered more than I expected from a capability point of view. 

Edited February 12, 20215 yr by Achmat

22 hours ago, Achmat said:

I had my aircons and geyser on the aux initially but at the time their was a software issue that caused the Aux to randomly disconnect and reconnect. I moved them to the normal load output but they've since fixed the software issue and there is now an option for the aux to remain connected if the grid is available. I just haven't had time to move the aircons and geyser back to the aux. I am also considering to use the aux for a generator, wind turbine or micro inverter. I could manage the aux loads using the battery SOC. 

The W on the aux screen as far as I recall is a limiter of how much power you want to send to the aux load from solar. So if you currently generating 6kw and you set this to 2 000w, then it will only send up to 2kw to the aux load. 

 

That is exactly how it's meant to be used. The sunsynk had really delivered more than I expected from a capability point of view. 

Do you have the same option to limit load before the inverter based on SoC?