Hi guys

I have a 5.5KVa single-phase generator with a house transfer switch able to select grid / generator / off.

I have an 8KW SunSynk single-phase hybrid inverter connected to grid for AC via its grid terminals - direct generator input is disconnected and not used on the SunSynk itself.

My SunSynk is set as such to never draw more than 2.2KW from the grid for powering the house and charging the batteries. E. g. half my generator's total capacity.

Can I safely start my generator, select generator on my transfer switch, and power the SunSynk from the generator without damaging or blowing up anything?

I have set the SunSynk to zero-export the day it was installed, my "meter-maintaining" output has been set to 0W in the software to prevent it trying to reverse to generator / grid.

I did check with the installer, they installed everything "behind" the point where the transfer switch ties the generator in to the house's domestic supply, so the SunSynk should "see" any AC the generator produces "as grid". If I'm making sense.

Any caveats or gotchas? Should I make sure (for example) that my panels are disconnected first (pull the breaker in each string's isolator box down) before starting the generator and throwing the switch after it has warmed up?

Definitely do not want to blow my generator or *gasp* the SunSynk itself.

Or am I just displaying my ignorance here in thinking this is possible?

I did consult the installer, but I'm also looking for some practical advice or hear what others found when doing / trying to do this. I've read the SunSynk documentation I could find, generally it seems as long as the AC load the inverter will cause is manageable for your generator, you cannot really damage anything even when using the "grid" input INSTEAD of "generator" inputs on the SunSynk.

Any advice?

Thanks

Edited December 10, 20232 yr by rylan76

The one kind-of issue with this idea,which is what the generator port helps negate,is the varying voltage/frequency stability on most cheaper generators (your non-diesel/non-inverter units),as they take load up and down - especially on the initial switch the output can sag which can cause the inverter to assume Mains is an issue and switch off,then when generator has no load and is stable try switching back repeatedly

There are tricks to mitigate this sag and appliance-modes on inverters handle these voltage fluctuations slightly better,but ymmv

53 minutes ago, PsyWulf said:

The one kind-of issue with this idea,which is what the generator port helps negate,is the varying voltage/frequency stability on most cheaper generators (your non-diesel/non-inverter units),as they take load up and down - especially on the initial switch the output can sag which can cause the inverter to assume Mains is an issue and switch off,then when generator has no load and is stable try switching back repeatedly

There are tricks to mitigate this sag and appliance-modes on inverters handle these voltage fluctuations slightly better,but ymmv

I would rather have your installer come and have the whole generator come through the Sunysnk as well for purposes mentioned above (stability), but also involving your installer would be an added measure of peace of mind should anything go wrong as s/he is then liable (hopefully) and also ensure that your generator settings on the Sunsynk are set correctly.

6 hours ago, rylan76 said:

Can I safely start my generator, select generator on my transfer switch, and power the SunSynk from the generator without damaging or blowing up anything?

According to Sunsynk documentation it is advised to use a generator double the size of the inverter in your case 15kva generator but as jou stated you don't use more than 2.2kw. Should you have a petrol generator with tubular frame the chances that the power head winding is of V0V configuration and the Sunsynk inverter will most probably not accept the input. I have never used smallish generators on the Sunsynk inverters so i can't say with certainty that it won't work on the inverter. Remember that if you are connecting the generator to the Grid port(utility input), you must fit a CT coil and set the Zero Export feature to around 150W. This will prevent the inverter exporting power back to the generator. The only way you will know if your 5.5kva(4400 watts) gen will work on the input port is to try and see, you won't blow up the inverter it will simply work or it won't. 

On the Sunsynk 8.8 kW inverter, it is best to connect these "small" petrol generators via a change-over switch to the AC mains input.

On the Grid settings open the Voltage and Frequency settings quite a bit to accommodate the variations of your generator.

Try something like:-

Grid voltage high - 255.0 V

Grid voltage low - 180.0 V

Grid frequency high - 53.0 Hz

Grid frequency low - 47.0 Hz

The Aux / Gen port will more than likely not accept this "small" unstable generator.

On my Old non firmware upgraded Sunsynk 8.8 kW machine there is no means to open the parameters for the Aux / Gen port, but on the Grid settings you can modify quite a bit.

Hi @rylan76

I have a 5.5kva petrol generator connected to my 16Kw DEYE so it is definitely doable and will work. 

Is there any reason why you do not connect it to the Aux/Gen port, in my experience it is better to have the generator connected to it, not sure what issues @TimCam has had using it, was it just the voltage and frequency settings @TimCam? 

The Aux/gen port has a less stringent requirement as far as generator power frequency and voltage are concerned and rams up the load on the generator slower than when connected to the Grid port. The DEYE does have a box to tick when connecting a generator to the grid port that opens up the permitted voltage and frequencies. Not sure if the Sunsynk has this as well as an option.

Do you have a Multimeter that you can check the frequency the generator is running at? 

I would suggest setting your generator at around 51.5hz, you want to adjust it so that when load is applied it is running at 50hz. 

One of the main issues that people have is that they set it to 50hz with no load, but when load is applied it drops down to say 48hz and the inverter disconnects. 

I did make a video on connecting to your generator which you might find useful. 

 

Edited December 10, 20232 yr by Sc00bs

@Sc00bs On my Aux port, under load when the frequency goes below 48 Hz, it drops out. the upper limit, I can't remember now.

On the Grid settings you can adjust it, but not on the Aux / Gen port.

I have an old 7.5 KVA petrol generator, and expect it to run up to 4 kW loads through the inverter. This is not possible through the Aux / Gen port, as it drops out, but through the Grid port is possible with opened parameters.

Exceptions are when a motor starts up, it does still drop out if load is high.

11 hours ago, TimCam said:

@Sc00bs On my Aux port, under load when the frequency goes below 48 Hz, it drops out. the upper limit, I can't remember now.

On the Grid settings you can adjust it, but not on the Aux / Gen port.

I have an old 7.5 KVA petrol generator, and expect it to run up to 4 kW loads through the inverter. This is not possible through the Aux / Gen port, as it drops out, but through the Grid port is possible with opened parameters.

Exceptions are when a motor starts up, it does still drop out if load is high.

@TimCam Have you tried adjusting your generator speed control under load so that it is sitting closer to 50hz?

When my generator has no load on it, it is sitting at about 51.5hz.  Sitting at 50hz under a 3.5kw load (5.5kva Petrol) 

You can see on the screen when it is within range as the colour changes, adjust it to the top end of the range. 

Makes it a bit easier to adjust your max load to put on the generator and so you don't have to open up your grid settings, would rather my inverter is not connected to the grid if it is not looking great. 

7 hours ago, Sc00bs said:

@TimCam Have you tried adjusting your generator speed control under load so that it is sitting closer to 50hz?

When my generator has no load on it, it is sitting at about 51.5hz.  Sitting at 50hz under a 3.5kw load (5.5kva Petrol) 

You can see on the screen when it is within range as the colour changes, adjust it to the top end of the range. 

Makes it a bit easier to adjust your max load to put on the generator and so you don't have to open up your grid settings, would rather my inverter is not connected to the grid if it is not looking great. 

Unfortunately fully adjusted, and still not enough under heavy load. Don't want to start "bending" the governor control.  Maybe one day if really needed I'll bend the governor mechanism. Hardly ever use the generator though. 👍

Yip, the "colour" changes too often on the Aux / Gen port under heavy load.

On 2023/12/11 at 5:37 PM, TimCam said:

Unfortunately fully adjusted, and still not enough under heavy load. Don't want to start "bending" the governor control.  Maybe one day if really needed I'll bend the governor mechanism. Hardly ever use the generator though. 👍

Yip, the "colour" changes too often on the Aux / Gen port under heavy load.

Maybe try restricting your load to a lower level at first until you can get it to connect and you can increase it after that. 

2 hours ago, Sc00bs said:

Maybe try restricting your load to a lower level at first until you can get it to connect and you can increase it after that. 

Thanks for the ideas, but if I use the generator once or twice a year, that's a lot.

On my setup, I can change the generator feed to Aux or Main AC via change-over switches, so if the need arises again, I'll fiddle some more.😀👍

On 2023/12/13 at 9:03 PM, TimCam said:

Thanks for the ideas, but if I use the generator once or twice a year, that's a lot.

On my setup, I can change the generator feed to Aux or Main AC via change-over switches, so if the need arises again, I'll fiddle some more.😀👍

If it's not broken then don't fix it I suppose 🙂 

On 2023/12/10 at 10:17 AM, rylan76 said:

Hi guys

I have a 5.5KVa single-phase generator with a house transfer switch able to select grid / generator / off.

I have an 8KW SunSynk single-phase hybrid inverter connected to grid for AC via its grid terminals - direct generator input is disconnected and not used on the SunSynk itself.

My SunSynk is set as such to never draw more than 2.2KW from the grid for powering the house and charging the batteries. E. g. half my generator's total capacity.

Can I safely start my generator, select generator on my transfer switch, and power the SunSynk from the generator without damaging or blowing up anything?

I have set the SunSynk to zero-export the day it was installed, my "meter-maintaining" output has been set to 0W in the software to prevent it trying to reverse to generator / grid.

I did check with the installer, they installed everything "behind" the point where the transfer switch ties the generator in to the house's domestic supply, so the SunSynk should "see" any AC the generator produces "as grid". If I'm making sense.

Any caveats or gotchas? Should I make sure (for example) that my panels are disconnected first (pull the breaker in each string's isolator box down) before starting the generator and throwing the switch after it has warmed up?

Definitely do not want to blow my generator or *gasp* the SunSynk itself.

Or am I just displaying my ignorance here in thinking this is possible?

I did consult the installer, but I'm also looking for some practical advice or hear what others found when doing / trying to do this. I've read the SunSynk documentation I could find, generally it seems as long as the AC load the inverter will cause is manageable for your generator, you cannot really damage anything even when using the "grid" input INSTEAD of "generator" inputs on the SunSynk.

Any advice?

Thanks

@rylan76did you have any success with your generator?