Hey all,

 

So yes, another thread about an inverter tripping the Earth Leakage - I know that most recommend you take the AC power to the inverter before the EL.

 

So my setup is currently 2x Luxpower SNA5000 inverter in parallel and solar panels. No batteries connected to the inverters yet (inverters set to no battery as well).

I have my "Eskom DB" which is the original DB which is being fed by Eskom only, this is where the inverters get their AC power feed from.

I have my "Inverter DB" which houses all the breakers which are fed by the inverters - there is a Manual Transfer Switch (MTS) which allows me to change the feed for this DB board between being fed via Eskom or being fed via the Inverters.

I initially wired power to the inverter after the Earth Leakage to see if I had any issues or not and all seemed to be fine as some people reported having issues and others not. I got the inverters setup and working on Tuesday and it was blending the PV with Eskom nicely. When loadshedding hit, the inverter stayed on but was not outputting any power (which is fine I guess, not the end of the world). Grid was restored and all was well, power being supplied via the inverters only.

Wednesday morning when waking up, I noticed that there was no power and there was no loadshedding scheduled either - so I checked and noticed that the Earth leakage on the Eskom DB board (feeding AC to the inverters) had tripped. So I played around and got the EL up and then got the inverters running and then changed over to the inverters supplying power via Eskom, the sun came out and the inverters did a good job of blending PV and Eskom grid power throughout the day. I had loadshedding at 4PM, PV was not enough to supply the load of the house and without a battery that meant no power. Although the inverters kept trying to power the house every 10 - 15 minutes it seemed as power could come on for a second and then nothing, the primary inverter gave error 28 (EPS overload) so I decided to slip my MTS over to Eskom to prevent the annoying power for a second every couple of minutes.

 

When loadshedding was over, I put the MTS back onto the inverters and all was running well - the house being powered by the inverters from Eskom grid.

Around 2am I woke up and heard a beeping noise, I fell asleep again thinking it was my trolley inverter (there was loadshedding from midnight until 2.30am). I woke up this morning to no power again - Earth Leakage on the Eskom DB board tripped. I tried to put it back up but it tripped, changed the MTS to Eskom and tried to put it the EL up and it stayed up, I then changed the MTS back to Inverters and all was well for around 10 seconds and then the EL on the Eskom board tripped.

I quickly decided to change the wiring to try power the inverters before the Earth Leakage (while typing this I just realized that I only changed the neutral to be before the EL and not the positive, which I suspect could be part of the issue). Then I noticed that as soon as I turned on power to the inverters the EL would trip (I suspect this is because live was being fed from after the EL and neutral before the EL)... It was early, I had just woken up and had limited time before I had to leave for work - I will try again tonight.

Anyways, after playing around a bit I changed it back so that both inverters were being fed after the EL as the EL tripping was only happening when I was trying to power the inverter DB via the inverters instead of Eskom.

 

I then decided to try each inverter feeding the inverter DB one at a time with a lower load and noticed that if the primary inverter was the only inverter feeding the inverter DB, that the EL on the Eskom DB would not trip. If I only had the secondary inverter feeding the inverter DB then it would take the load and trip after around 10 seconds again.

 

So currently, I have turned off the input on my second / slave inverter and am only running the primary inverter to feed my inverter DB.

 

I am a bit puzzled as to why all of a sudden I am having this issue and am wondering if it has something to do with the 2nd inverter?
I have not yet had a chance to set each inverter to single (not parallel) and test each the secondary inverter like this.

I will also try and feed both live and neutral before the EL and see if that resolves the issues.

 

Oh, I also did a firmware update yesterday afternoon on both inverters - not sure if this is playing a role, I also noticed that there is now this setting and I am not sure whether I should have it enabled or not?

So I think when I get home, I first want to take the slave / secondary inverter out of parallel mode and run just that one and see if it still causes the EL to trip. If so, I suspect an issue with this inverter as it does not make sense to me as to why the primary / master inverter can power the DB without tripping the EL but the secondary / slave inverter trips the EL all of a sudden.

 

If the EL does not trip after taking the inverter out of parallel, then I will rewire both inverters to get power before the EL and see how things run then. Still weird as it was all running well before this morning and it only trips when power is being fed from the inverters.

 

@TaliaB @Scorp007

You guys are quite knowledgable, anything you can think of which I could try while I am at it or anything I could look for?

Edited August 24, 20233 yr by PsyCLown

36 minutes ago, PsyCLown said:

So I think when I get home, I first want to take the slave / secondary inverter out of parallel mode and run just that one and see if it still causes the EL to trip. If so, I suspect an issue with this inverter as it does not make sense to me as to why the primary / master inverter can power the DB without tripping the EL but the secondary / slave inverter trips the EL all of a sudden.

 

If the EL does not trip after taking the inverter out of parallel, then I will rewire both inverters to get power before the EL and see how things run then. Still weird as it was all running well before this morning and it only trips when power is being fed from the inverters.

 

@TaliaB @Scorp007

You guys are quite knowledgable, anything you can think of which I could try while I am at it or anything I could look for?

I don't know this inverter but did you change the phase to before the E/L when you found you only moved the neutral? 

Try using the inverters one one when after the E/L. Try to find if it is not a specific load tripping it but it does sound as if it is inverter related as the E/L doesn't trip with bypass on grid only. 

Perhaps do a N-E bond as has been suggested by someone one the forum. 

Are both inverters on the same firmware version. 

Let's see if @TaliaB has time to give his specialist input/help. 

8 minutes ago, Scorp007 said:

I don't know this inverter but did you change the phase to before the E/L when you found you only moved the neutral? 

Try using the inverters one one when after the E/L. Try to find if it is not a specific load tripping it but it does sound as if it is inverter related as the E/L doesn't trip with bypass on grid only. 

Perhaps do a N-E bond as has been suggested by someone one the forum. 

Are both inverters on the same firmware version. 

Let's see if @TaliaB has time to give his specialist input/help. 

Its a single phase system, both inverters were set to single phase parallel and they were working fine like this on Tuesday & Wednesday with much higher loads. EL only seemed to trip after loadshedding (during the night) and I was able to reset the EL without issues.

 

This morning is when the EL kept tripping after a few seconds of both inverters taking the load (was not even a high load, around 2KW in total, so 1KW per inverter).

The primary invertor alone did not trip the EL, but the second/slave inverter alone did trip the EL. So for today I have had only the primary inverter running and have turned some equipment off to prevent it from exceeding the 5KW inverter limit.

Both inverters are on the latest firmware (was updated yesterday afternoon), I will try enable the N-PE option on the inverter. I think that option only became available after the firmware upgrade as I do not recall seeing it previously.

So far what we know is the slave seems to trip the E/L. So the plan would be to configure both as single inverters. You have the master only connected now. 

Simulate LS by switching off the grid while you have grid. Don't wait until you have LS and stuck without power. Ensure you know what loads you have on the inverter and take the reading. Leave the grid off for a time greater than what it took to trip before. If all is clear after say 5 tries then disconnect it from grid and do the same with the slave that is also set up as a single inverter. Same loads and same way of disconnecting the grid. 

When connecting both inverters and connecting more loads because you have 2 inverters you are introducing a 2nd variable which could be an earth fault on one of these extra loads and thinking it is the 2nd inverter causing it.

Give us your results and then we take it further. This is not a fault or tome to guess but rather follow a step by step approach while you have grid. 

Edited August 24, 20233 yr by Scorp007

Ok, so back home and I have done a bit of testing.

 

I changed both inverters back to Single mode (no longer parallel).

The load is similar to this morning, which is just over 2KW. The "slave" inverter has not tripped the EL (although there is no sun, so no PV power - not sure if this makes any difference).

 

I then set both inverters back to single phase parallel and with the same load of just over 2KW it now works fine without tripping the EL. The only difference between now and this morning is that this morning there might have been a little bit of sun on the panels (under 100W) and now there is no sun.

 

Remember, I do not have a battery connected so if I turn Eskom off (power being fed to the inverters) then I have no power. If the inverters are off and the power comes back then the EL on the Eskom DB always trips. I need to first change the MTS to being fed from Eskom, let the inverters power up and then I can change the MTS to being fed from the inverters to avoid the EL tripping.

 

I have now redone the wiring and have the inverters being powered before the EL and I no longer have the EL tripping when there is no power on the inverters, the MTS is on the inverter to power the inverter DB and power is restored to the inverters. The inverters boot up and only when the relay kicks in does the DB get power.

So I think I will leave it as such for now and monitor and see if that has solved my issues - tomorrow morning I have loadshedding from 6am so will be hard to test whether the inverter trips anything or what happens as I will be at work by the time the PV is producing enough power to carry the load and before power is restored at 8.30am. 🤷‍♂️

 

I have NOT made any changes to the N-PE Connect setting, this is still set to disable on both inverters.

25 minutes ago, PsyCLown said:

Ok, so back home and I have done a bit of testing.

 

I changed both inverters back to Single mode (no longer parallel).

The load is similar to this morning, which is just over 2KW. The "slave" inverter has not tripped the EL (although there is no sun, so no PV power - not sure if this makes any difference).

 

I then set both inverters back to single phase parallel and with the same load of just over 2KW it now works fine without tripping the EL. The only difference between now and this morning is that this morning there might have been a little bit of sun on the panels (under 100W) and now there is no sun.

 

Remember, I do not have a battery connected so if I turn Eskom off (power being fed to the inverters) then I have no power. If the inverters are off and the power comes back then the EL on the Eskom DB always trips. I need to first change the MTS to being fed from Eskom, let the inverters power up and then I can change the MTS to being fed from the inverters to avoid the EL tripping.

 

I have now redone the wiring and have the inverters being powered before the EL and I no longer have the EL tripping when there is no power on the inverters, the MTS is on the inverter to power the inverter DB and power is restored to the inverters. The inverters boot up and only when the relay kicks in does the DB get power.

So I think I will leave it as such for now and monitor and see if that has solved my issues - tomorrow morning I have loadshedding from 6am so will be hard to test whether the inverter trips anything or what happens as I will be at work by the time the PV is producing enough power to carry the load and before power is restored at 8.30am. 🤷‍♂️

 

I have NOT made any changes to the N-PE Connect setting, this is still set to disable on both inverters.

Sorry I forgot you cannot run from battery. What fooled me is that you running the inverters at night on the inverters instead of grid and that is when you find these trips of the E/L. 

Have you tried running only on the grid during a few nights?

23 minutes ago, Scorp007 said:

Sorry I forgot you cannot run from battery. What fooled me is that you running the inverters at night on the inverters instead of grid and that is when you find these trips of the E/L. 

Have you tried running only on the grid during a few nights?

So when I run on the inverters at night, it is basically just passing the Eskom power through the inverter - the reason I want to do this is so that I can get some history and data in terms of my consumption and so that my PV yield vs import from Eskom figures are accurate.

 

With the MTS on Eskom only and the inverters being powered from Eskom there were no EL trips.

53 minutes ago, PsyCLown said:

So when I run on the inverters at night, it is basically just passing the Eskom power through the inverter - the reason I want to do this is so that I can get some history and data in terms of my consumption and so that my PV yield vs import from Eskom figures are accurate.

 

With the MTS on Eskom only and the inverters being powered from Eskom there were no EL trips.

Sorry guys i was offline today was busy with the misses seeing that i am home for a few days. All i can say is definetly both inverters before the EL, also each input of inverter on dedicated mcb from the Eskom db. I have never done an inverter install without a battery but it looks like you are on the right track, see what it does when solar wakes up in the morning. Ensure that inverters are synchronized but i am sure you would have checked that. What is the total kwp of your solar array?

12 hours ago, TaliaB said:

Sorry guys i was offline today was busy with the misses seeing that i am home for a few days. All i can say is definetly both inverters before the EL, also each input of inverter on dedicated mcb from the Eskom db. I have never done an inverter install without a battery but it looks like you are on the right track, see what it does when solar wakes up in the morning. Ensure that inverters are synchronized but i am sure you would have checked that. What is the total kwp of your solar array?

 

So this is how I have the breakers which feed the inverters.

 

MCB (63A) which then powers the 2x 30A breakers (1st 30A is for inverter 1, 2nd 30A is for inverter 2). So I can isolate per inverter or the MCB for both inverters.

Power being fed from the inverter is similar with 2x smaller breakers feeding into a larger 63A MCB which then goes to the MTS.

 

6200W for the full solar array, currently 5x panels per inverter so 3100W per inverter.

This morning all seemed fine, a bit overcast in JHB this morning and I had loadshedding from 6am to 8.30am, the inverters still try to power the load when they get a little bit of sun on the panels but then throw an error stating EPS overload (not enough PV to power the load).

Although once Eskom restored power, all came back online and nothing tripped I believe and its been blending PV with grid.

 

 

What threw me off was the fact that yesterday morning the EL was tripping but only with both inverters taking the load and then EL stopped tripping when it was only 1 inverter taking the load.

 

How would I actually check that the inverters are synchronized? Other than the inverters giving me an error saying there is a comms issue, I do not know how to tell?

Edited August 25, 20233 yr by PsyCLown

 

48 minutes ago, PsyCLown said:

How would I actually check that the inverters are synchronized? Other than the inverters giving me an error saying there is a comms issue, I do not know how to tell?

Check on page 6 off the parralel setup.

Hybrid-Parallel-Connection-Guidance.pdf

13 minutes ago, TaliaB said:

 

Check on page 6 off the parralel setup.

Hybrid-Parallel-Connection-Guidance.pdf 1.2 MB · 1 download

I have added them as parallel via the website portal and I can select the Parallel group to view the combined info of the inverters.