Hi all

with the current loadshedding situation, I have noticed that my incoming AC voltage is bouncing around all over the place. It on a regular basis goes up to 240V and sometimes even close to 245V.

I have now installed a 'smart' 63A breaker between my incoming mains and the rest of my DB board to be able to cut my Eskom feed. During the day I have more than sufficient PV to be off-grid. So am contemplating of programming a timer on that breaker to separate myself from the grid during the day and have my inverter feed 'clean' power to my house.

Any downsides to this?

And what voltage should I set the inverter to? The standard 230V? Or something different?

What type of inverter are we talking about? If it is one of the common inverters that get used to feed power to the house, there should surely be some type of setting to prioritise solar over grid.

Edited October 4, 20223 yr by GreenFields

I'm running my inverter on 230v.  What I'm noticing is that the City Power voltage is around 220v when loadshedding is over, sometimes as low as 200v, gradually ramping up to 230v after about 2 hours, where it remains until the next cut.

I've played around with setting the inverter to 220v and 240v to see if I can squeeze out a bit more from the battery but I cannot say that there is any measurable difference, hence I'm just leaving it on 230v.

59 minutes ago, GreenFields said:

What type of inverter are we talking about?

Sunsynk - so it synchs with the incoming mains

1 hour ago, GreenFields said:

If it is one of the common inverters that get used to feed power to the house, there should surely be some type of setting to prioritise solar over grid.

The source is not the problem. The problem is that the inverter synchs the voltage to the incoming Eskom feed - even if I am running fully on solar

27 minutes ago, wolfandy said:

Sunsynk - so it synchs with the incoming mains

28 minutes ago, wolfandy said:

The source is not the problem. The problem is that the inverter synchs the voltage to the incoming Eskom feed - even if I am running fully on solar

Anything that can be resolved simply by setting the inverter's grid parameters for protection against high and low voltage? That should also provide protection at night. And maybe combine that with the the inverter's time-of-use settings? That should also help you for days when solar production is low, so that you don't have to take the time to change your smart timer. It might be avoiding the issue, not giving you the type of answer you're looking for, but I'm just wondering whether the extra smart breaker is really needed over and above the functions that are built into the inverter.

My Goodwe has a "safety code" setting. This setting determines the expected grid voltage and frequency. By default this is set to "warehouse". Don't ask: I don't know. But if I set it to "South Africa" it expects 230v @ 50Hz, give or take a tolerance either way. And if the grid voltage is too low or too high, it disconnects. It then monitors the incoming voltage, and if it stabilises within the acceptable range, it reconnects again.

I'd be surprised if the Sunsynk doesn't have something similar.

The voltage is not required to be exactly 230 V. There is a tolerance. 5% (if that's what it is), gives you 11.5V either way. Anyway, I have set my inverter for our safety code, and I leave it to disconnect when it sees fit.

3 hours ago, wolfandy said:

I have now installed a 'smart' 63A breaker between my incoming mains and the rest of my DB board to be able to cut my Eskom feed. During the day I have more than sufficient PV to be off-grid. So am contemplating of programming a timer on that breaker to separate myself from the grid during the day and have my inverter feed 'clean' power to my house.

Any downsides to this?

On overcast days the grid voltage will still fluctuate, but you may have insufficient PV, and so the batteries will discharge. I have had mine disconnect round 9 in the morning after running off batteries all night. When there's plenty of PV this is no big deal, but if it's overcast, my battery can get awful low, and the rule I have to charge from grid if necessary will fail because it ain't connected to the grid.

So always plan for overcast days, not bright days.
 

48 minutes ago, GreenFields said:

Anything that can be resolved simply by setting the inverter's grid parameters for protection against high and low voltage?

 I have to admit that I do not know what my Sunsynk is capable of in this regard. Will look into Google for this

2 hours ago, GreenFields said:

Anything that can be resolved simply by setting the inverter's grid parameters for protection against high and low voltage? That should also provide protection at night.

Found the settings 😀

49 minutes ago, Bobster. said:

My Goodwe has a "safety code" setting. This setting determines the expected grid voltage and frequency. By default this is set to "warehouse". Don't ask: I don't know. But if I set it to "South Africa" it expects 230v @ 50Hz, give or take a tolerance either way. And if the grid voltage is too low or too high, it disconnects. It then monitors the incoming voltage, and if it stabilises within the acceptable range, it reconnects again.

Can you see what your exact settings for high and low voltage are?

As you can see from the above, my Sunsynk is set to max. 265V and min. 185V. That range feels too wide for me

Would be curious about what others are using for this 😬

1 hour ago, wolfandy said:

Would be curious about what others are using for this 😬

Old thread that may be of interest.

https://powerforum.co.za/topic/1100-sa-mains-voltage-range/

Also, possibly also an interesting read.

https://en.wikipedia.org/wiki/Mains_electricity

I checked my Deye, and found the settings to be just as yours, 265V max and 185V min. Seems like some default for that manufacturer.

Now I might be disconnecting more frequently going forward, but I'm going to opt for a more standardized power quality and see how it goes.

7 hours ago, wolfandy said:

Found the settings 😀

Can you see what your exact settings for high and low voltage are?

As you can see from the above, my Sunsynk is set to max. 265V and min. 185V. That range feels too wide for me

Would be curious about what others are using for this 😬

I can't see the minimum & maximum. Possibly they are stipulated in a manual somewhere. 

I know that if I set it to "50hz default" it never disconnects from the grid, it just keeps on mimicking the grid voltage. 

If I set it to "South africa" it disconnects somewhere south of 200V. I'd have to watch it after a load shed to try to deduce a more accurate figure. Over voltages are less of a problem in my life. 

What is needed in your case is a tolerance (10% as a thumbsuck example). Your appliances will be built to a tolerance, and past that upper or outer bound, they may sustain damage or deteriorate. Get those figures & you can reprogram your inverter. Probably these are the factory settings. 

8 hours ago, Bobster. said:

On overcast days the grid voltage will still fluctuate, but you may have insufficient PV, and so the batteries will discharge. I have had mine disconnect round 9 in the morning after running off batteries all night. When there's plenty of PV this is no big deal, but if it's overcast, my battery can get awful low, and the rule I have to charge from grid if necessary will fail because it ain't connected to the grid.

So always plan for overcast days, not bright days.
 

I think some of us are looking at our own local voltage and might think that is the country voltage. Swinging voltage is a factor of loading by the local network and not Eskom. Transformers not always run with tap changers on auto. Manually controlled by a control room.

In my area we have a very stable voltage. Great earthing and we never hear of damage due to spikes or surges. The earthing is key to preventing damage. Also our longest outing was 36hrs when a mini sub burnt out. I think quite a good record for over 22years.

Not sure why should the voltage be steady or not on overcast days?

7 hours ago, Scorp007 said:

Not sure why should the voltage be steady or not on overcast days?

I didn't mean to suggest that it would be. I was referring to the idea of having a programmed breaker to disconnect from grid during the day when PV is available. If this is done simply by time, it could have unforeseen, and unwanted, consequences on an overcast day.

Where I live the voltage fluctuates a bit. It used to move between 210 and mid 180s. This had my Goodwe disconnecting all the time. On overcast days when I might need to charge from grid to get through a load shed, I'd set it to the "50Hz default" code, it then became very unfussy about the input voltage.

Then a local substation burned out (or bits of it burned). We were out for the best part of the day, but since then we get a pretty good 230ish V most of the time, with the only drop offs being right after load shedding. So some of our problems (I know that other neighbours were worried because various things were misbehaving or taking a long time) were maybe down to old components in that sub station.

10 hours ago, Bobster. said:

I can't see the minimum & maximum. Possibly they are stipulated in a manual somewhere. 

I know that if I set it to "50hz default" it never disconnects from the grid, it just keeps on mimicking the grid voltage. 

If I set it to "South africa" it disconnects somewhere south of 200V. I'd have to watch it after a load shed to try to deduce a more accurate figure. Over voltages are less of a problem in my life. 

By sheer chance I just observed the moment of reconnect after a load shed. Grid voltage was 196.5 V.

1 hour ago, Bobster. said:

By sheer chance I just observed the moment of reconnect after a load shed. Grid voltage was 196.5 V.

I would advise against running "50Hz Default" on your inverter for various reasons - most important of which is that doing so means it is not NRS097 compliant unless SA grid code is selected.

The other is that certain safety features seem to be disabled in 50Hz default.

On all our installs the type of inverters we use allow us to change the output voltage, we set the output voltage to what we get from eskom (if we get 230v from eskom we set the inverters to 230v). This way the inverter does not need to step down/up voltages that much. Sometimes the voltage changes during peak times but not much we can do about that. 

 

In certain parts of Gauteng we have seen customers voltage from eskom/city power drop to as low as 170volts these areas usually have ongoing power outages and are indicative of a transformer/supply/load issue

Edited October 5, 20223 yr by Treschen

2 hours ago, P1000 said:

I would advise against running "50Hz Default" on your inverter for various reasons - most important of which is that doing so means it is not NRS097 compliant unless SA grid code is selected.

The other is that certain safety features seem to be disabled in 50Hz default.

Thanks. I wondered about the implications of that. I don't run it in that mode anymore. I mention it here for the sake of example. I had figured out that letting it connect to the grid irrespective of voltage was perhaps not the smartest thing to do.

Edited October 5, 20223 yr by Bobster.
clarity

2 hours ago, P1000 said:

I would advise against running "50Hz Default" on your inverter for various reasons - most important of which is that doing so means it is not NRS097 compliant unless SA grid code is selected.

The other is that certain safety features seem to be disabled in 50Hz default.

You raise a very good point. The grid is managed based on the approved parameters. This means we have to keep to the same when we select a grid code. I have never seen my grid tied disconnection due to the level of the grid. Unlike Mrs Google my unit does not take 5min to connect but less than 1min. This is the only point where I have an ongoing recording of voltage.

4 hours ago, P1000 said:

I would advise against running "50Hz Default" on your inverter for various reasons - most important of which is that doing so means it is not NRS097 compliant unless SA grid code is selected.

The other is that certain safety features seem to be disabled in 50Hz default.

What do you mean by this?

50Hz default can really mean a lot of things, so it is down to the fine text of what that option entails.  But I certainly would not want an inverter that would allow a frequency outside a pretty tight 50Hz ± 1 Hz band, or maybe up to 1.5Hz.

But ultimately why I would not risk letting the inverter "auto-detect" is that if you have some idiot that back feeds at a different frequency, you would not want to have that influence your local installation.  Smaller non-inverter generators are guilty of this, their frequencies vary wildly, it is actually insane how unstable they are.

SA grid cannot and will never not operate outside 50 Hz.  The turbines at power stations are directly coupled to the grid, so they are spinning at some multiple of the grid frequency.  Turbines cannot spin at other frequencies, just like a full laundry machine can basically "crash" the drum at some slower and higher speeds.  The turbine would explode.  So they trip the turbine off-line if the grid frequency is outside the safe operating band.  So we are well and truly stuck at 50Hz.

I'm no expert at what the exact tolerance is, but if America & Russia is anything to go by, the safe tolerance is around 1Hz or so.  And operating outside that frequency at load for any amount of time will very rapidly wear out the turbine mechanical components.

Now I digress you may likely have all this theory already and I don't fully know what "50Hz by default" means, but I again wouldn't want to allow arbitrary grid frequency on an inverter or any kind of "auto-detect".

Edited October 5, 20223 yr by Gnome

Just now, Gnome said:

What do you mean by this?

That reply was to bobster that has a GoodWe es5048. In that inverter, 50Hz Default, AKA "Wharehouse" setting is a test mode. If it is not set to SA grid code, it is not compliant. If the inverter is set to SA grid code, it will only tolerate voltages of 230V±10%, which means that it would have disconnected and go into backup/ups mode when the grid voltage dropped to "196.5 V".

1 minute ago, P1000 said:

That reply was to bobster that has a GoodWe es5048. In that inverter, 50Hz Default, AKA "Wharehouse" setting is a test mode. If it is not set to SA grid code, it is not compliant. If the inverter is set to SA grid code, it will only tolerate voltages of 230V±10%, which means that it would have disconnected and go into backup/ups mode when the grid voltage dropped to "196.5 V".

Yeah I assumed there was some fine print I'm missing, thanks for clearing that up   It is more about the voltage than the frequency

4 hours ago, Gnome said:

But ultimately why I would not risk letting the inverter "auto-detect" is that if you have some idiot that back feeds at a different frequency, you would not..........

As you explained it would not be possible for one idiot to change the whole Eskom grid frequency to affect your system. Thus I doubt that this person's inverter could do it. His setting might to try but without success.  So one less thing to worry about 😃

1 hour ago, Scorp007 said:

As you explained it would not be possible for one idiot to change the whole Eskom grid frequency to affect your system. Thus I doubt that this person's inverter could do it. His setting might to try but without success.  So one less thing to worry about 😃

For Eskom yes.  If you back feed you could output any frequency you want while there is load shedding.

1 hour ago, Gnome said:

For Eskom yes.  If you back feed you could output any frequency you want while there is load shedding.

Nope, don't know of any commonly used  inverter that will back feed (export) while load-shedding (No AC input). My SunSynk will absolutely not export without Eskom connected. I've tried it, but no OP voltage. I'm inquisitive and test things.😂

51 minutes ago, TimCam said:

Nope, don't know of any commonly used  inverter that will back feed (export) while load-shedding (No AC input). My SunSynk will absolutely not export without Eskom connected. I've tried it, but no OP voltage. I'm inquisitive and test things.😂

You are spot on. This is the one thing  grid inverters must do to be on the NRS list. I have not seen any that can do it. For sure my Solis also switches off. Even the cheap 1kw unit around would switch off so no export without grid.

These inverters MUST synch with the grid voltage and frequency to operate..........

Edited October 5, 20223 yr by Scorp007