INVT on Grid inverter problem - restarting

[eddysacc]

We have got an INVT ongrid inverter (invt mg  6ktl-2m) and sincevwe upgraded more panels it restarts frequently when the inverter is maxing out about midday.

 

It also gets very hot although we added a bit fan for active cooling.

 

Is there is too much output from all the panels for the inveter now?

 

Have a look - advice very much appreciated.

 

 

The setup as follows:

 

String 1: 8x 450w.mono panels

String 2: 6x 550w mono panels

 

 

 

 

 

[JBChiangRai]

Most grid-tied inverters will ramp up their output until they either reach the rated capacity and stay nailed close to that

 

or

 

Ramp up their output voltage until they hit the maximum voltage allowed and then error and restart.

 

I suspect yours is the latter.  This happens on a weak grid connection because there is insufficient local demand on your side of the transformer.  

[Fruit Trader]

43 minutes ago, eddysacc said:

It also gets very hot although we added a bit fan for active cooling.

What does the fault history show?

[retarius]

I have been thinking about getting solar panels but this conversation is like a foreign language to me. I can't understand any of it. I think I'll forget the whole idea. 

[Crossy]

My first thought was over-voltage on the PV, but that looks not to be the case.

 

As above, does the fault-log show anything useful?

[Crossy]

44 minutes ago, retarius said:

I have been thinking about getting solar panels but this conversation is like a foreign language to me. I can't understand any of it. I think I'll forget the whole idea. 

 

Don't do that, yet.

 

Solar does have its own vocabulary, but it's really not rocket-science.

 

Do you have any basic knowledge of electricity, volts, amps, ohms? Got a multimeter?

[eddysacc]

On 8/31/2023 at 3:21 PM, JBChiangRai said:

Most grid-tied inverters will ramp up their output until they either reach the rated capacity and stay nailed close to that

 

or

 

Ramp up their output voltage until they hit the maximum voltage allowed and then error and restart.

 

I suspect yours is the latter.  This happens on a weak grid connection because there is insufficient local demand on your side of the transformer.  

Just adding some background info here:

 

 

I guess the Solar panels are already oversized for the inverter.

?

It's string 1 8x450w = 3600w

      String 2 6x550 = 3300 w

 

I used to use only string 1 for quite some time and I don't remember having had these issues.

 

 

Now with string 2 working that's when the issues started to occur.

 

The inverter now also gets very hot.

I added acrive cooling but arrow d midday tye inveter would hit 60° CELSIUS on a sunny day for sure.

 

 

That's for your helpful comments JB:

The inverter indeed never goes over its rated AC output. that's true.

That might be it. Although there are some restarts when 6000w ac output is not hit.

 

 

The thing avoit the voltage is what I still don't know how to figure out.

 

 

Above I posted some screenshot of the 550w panels including some max voltage numbers.

How to calculate it?

 

Could high voltage surges cause some trouble here?

 

 

 

 

 

 

[JBChiangRai]

22 minutes ago, eddysacc said:

Just adding some background info here:

 

 

I guess the Solar panels are already oversized for the inverter.

?

It's string 1 8x450w = 3600w

      String 2 6x550 = 3300 w

 

I used to use only string 1 for quite some time and I don't remember having had these issues.

 

 

Now with string 2 working that's when the issues started to occur.

 

The inverter now also gets very hot.

I added acrive cooling but arrow d midday tye inveter would hit 60° CELSIUS on a sunny day for sure.

 

 

That's for your helpful comments JB:

The inverter indeed never goes over its rated AC output. that's true.

That might be it. Although there are some restarts when 6000w ac output is not hit.

 

 

The thing avoit the voltage is what I still don't know how to figure out.

 

 

Above I posted some screenshot of the 550w panels including some max voltage numbers.

How to calculate it?

 

Could high voltage surges cause some trouble here?

 

 

 

 

 

 

I would buy a plug in voltmeter on Lazada and plug it in a socket and see how high it gets before it resets.  Crossy will probably know what the permitted voltage is, probably 253v or something like that, if it's hitting that then shutting off you will know it is a weak grid.

 

Alternatively, try turning on a few heavy loads (air cons on cold etc) and see if it still happens, if it doesn't the problem is a weak grid. You could try removing a few panels until it doesn't happen (or enjoy the cool air).

 

I have 2 grid-tied inverters and 2 of mine will do the same, I've cadenced the voltages so they go off in succession until they are happy.

[eddysacc]

On 8/31/2023 at 3:29 PM, Fruit Trader said:

What does the fault history show?

It shows no fault.

I just resetted the inverter the day before. It might be deleted.

 

Let's wait for a sunny day and check again.

 

 

 

 

[eddysacc]

1 minute ago, JBChiangRai said:

I would buy a plug in voltmeter on Lazada and plug it in a socket and see how high it gets before it resets.  Crossy will probably know what the permitted voltage is, probably 253v or something like that, if it's hitting that then shutting off you will know it is a weak grid.

 

Alternatively, try turning on a few heavy loads (air cons on cold etc) and see if it still happens, if it doesn't the problem is a weak grid. You could try removing a few panels until it doesn't happen (or enjoy the cool air).

 

I have 2 grid-tied inverters and 2 of mine will do the same, I've cadenced the voltages so they go off in succession until they are happy.

The export to grid is turned on but limited to 2500 Watt.

 

So there is always some demand.

Should I put that figure up?

[Fruit Trader]

18 minutes ago, eddysacc said:

It shows no fault.

I just resetted the inverter the day before. It might be deleted.

 

Let's wait for a sunny day and check again.

 

 

 

 

If an inverter restarts frequently the first port of call is the fault log. If the logs show no errors then begin looking elsewhere.

 

In theory software should not make a restart during normal operation without logging the reason but there's always a possibility you have a condition that's not been accounted for or might even be one that's resetting the hardware without the software ever knowing.

 

The high temperatures you speak of are of interest to me because I have made some mods to my inverters and others that use passive cooling. These mods help during high load and high ambient temperature conditions.

Edited September 3, 2023 by Fruit Trader

[JBChiangRai]

30 minutes ago, eddysacc said:

The export to grid is turned on but limited to 2500 Watt.

 

So there is always some demand.

Should I put that figure up?

Definitely set it to the rating of the inverter (6Kw ?)

 

I think that is your problem.

[indyo]

did you try also to run with the grid 2 only?

[bluejets]

On 8/31/2023 at 5:45 PM, eddysacc said:

String 1: 8x 450w.mono panels

String 2: 6x 550w mono panels

could have something to do with this....... most manufacturers will tell you not to mis-match panels.

[bluejets]

On 8/31/2023 at 7:24 PM, retarius said:

I have been thinking about getting solar panels but this conversation is like a foreign language to me. I can't understand any of it. I think I'll forget the whole idea. 

Having solar is not a problem if you leave the install to those who best know what they are doing.

You don't need to know.

i.e. reputable solar installers, not the vast majority of diy "experts".

[JBChiangRai]

On 9/3/2023 at 2:37 PM, JBChiangRai said:

Definitely set it to the rating of the inverter (6Kw ?)

 

I think that is your problem.

Did you increase the export to grid figure to 6000w?

 

I think now you have fitted extra panels, it's exporting 2500 watt then there is insufficient local demand in your house for the remaining 3500 watt and it restarts.

[Fruit Trader]

6 hours ago, JBChiangRai said:

Did you increase the export to grid figure to 6000w?

 

I think now you have fitted extra panels, it's exporting 2500 watt then there is insufficient local demand in your house for the remaining 3500 watt and it restarts.

The inverter has no idea that there is a potential 3500 watts not being consumed. It is only interested in the real time demand and any limits imposed by settings. A de-rated inverter will happily produce a tiny fraction of what the attached solar array is capable of.

If healthy, the only real problem for an inverter is over/under voltages at either end of its process or excess temperature generated around the switching electronics.

 

Note. I did not grab this information from the internet black hole, it comes from studying the disassembled code of several on grid solar inverters made by Chinese enthusiasts. 

[JBChiangRai]

10 minutes ago, Fruit Trader said:

The inverter has no idea that there is a potential 3500 watts not being consumed. It is only interested in the real time demand and any limits imposed by settings. A de-rated inverter will happily produce a tiny fraction of what the attached solar array is capable of.

If healthy, the only real problem for an inverter is over/under voltages at either end of its process or excess temperature generated around the switching electronics.

 

Note. I did not grab this information from the internet black hole, it comes from studying the disassembled code of several on grid solar inverters made by Chinese enthusiasts. 

My 3 Grid-Tied inverters do not behave as you describe.  They will attempt to produce as much power as they can from the available sunlight, and if I am not consuming it in the house and the grid is too weak to take it, the voltage will climb until it hits the limit and error.  The they restart after a minute and the process repeats.

 

In my inverters, the settings are available to change and I have cadenced them so that Inverter 1 first shuts off, Inverter 2 is set 1 volt higher, Inverter 3 is set yet another volt higher.

Edited September 6, 2023 by JBChiangRai

[Fruit Trader]

9 minutes ago, JBChiangRai said:

My 3 Grid-Tied inverters di nit behave as you describe.  They will attempt to produce as much power as they can from the available sunlight, and if I am not consuming it in the house and the grid is too weak to take it, the voltage will climb until it hits the limit and error.  The they restart after a minute and the process repeats.

There is something very wrong if an inverter produces beyond demand to the point where it faults. If the max grid voltage parameter is being exceeded then that's another story which really should be looked at. Most inverters are certified with country code parameters which are sometimes too narrow for Thailand's grid.

[JBChiangRai]

1 minute ago, Fruit Trader said:

There is something very wrong if an inverter produces beyond demand to the point where it faults. If the max grid voltage parameter is being exceeded then that's another story which really should be looked at. Most inverters are certified with country code parameters which are sometimes too narrow for Thailand's grid.

In my case it is the max grid voltage parameter which is being exceeded.

[JBChiangRai]

30 minutes ago, JBChiangRai said:

In my case it is the max grid voltage parameter which is being exceeded.

The inverters raise the voltage of their output in an attempt to push their power out to the grid.

 

I was surprised they don't simply wind down their gain as they approach the max grid voltage parameter so as not to exceed it.

 

I couldn't find any other setting that might help.  I would love to have them sit close to max grid voltage parameter and not exceed it and error.

[Fruit Trader]

1 hour ago, JBChiangRai said:

The inverters raise the voltage of their output in an attempt to push their power out to the grid.

 

I was surprised they don't simply wind down their gain as they approach the max grid voltage parameter so as not to exceed it.

 

I couldn't find any other setting that might help.  I would love to have them sit close to max grid voltage parameter and not exceed it and error.

Thats a quite a common problem and not always easy to fix when the voltage values are locked and set to supply authority spec. 

I have a single phase inverter on a each phase and there were times when grid voltage was exceeded on one phase. I initially changed country code to fix the problem then later begged the manufactrurer for the parameter address list.

Why does the inverter not adjust as it approaches limit is a good question. The inverter will be making adjustment up to a point but the final decision to fault will be down to time limits to get into the lower level set by country spec. 

[Crossy]

Yeah, our Sofar pure on-grid and on-grid hybrid will both kill all generation if the Grid Over-Voltage parameter is exceeded although they don't actually reset. They both come back online after a minute or so, so no mega impact on generation (and the hybrid keeps charging the batteries if they are not full). 

 

I have asked Sofar about throttling as the max grid voltage is approached but ...

[JBChiangRai]

30 minutes ago, Fruit Trader said:

Thats a quite a common problem and not always easy to fix when the voltage values are locked and set to supply authority spec. 

I have a single phase inverter on a each phase and there were times when grid voltage was exceeded on one phase. I initially changed country code to fix the problem then later begged the manufactrurer for the parameter address list.

Why does the inverter not adjust as it approaches limit is a good question. The inverter will be making adjustment up to a point but the final decision to fault will be down to time limits to get into the lower level set by country spec. 

I do have the Admin password and change all the parameter's on my MUST Grid-Tied inverter.

[eddysacc]

Sorry for the late reply. There were busy days with the 3 kids.

 

Today there was a sunny day after all. Perfect for observing if the changes of the inverter settings made a difference.

 

And what can I say?

 

The inverter is still restarting when hitting 5.8kw output.

 

A) it might not be the export Setting in my case

 

B) IT MIGHT not be the possibly overheating of the inverter as I upgraded a stronger fan for cooling.

 

So it must be too many panels output for the 6kw rated on grid inverter.

 

 

Thank you for All the advice and Support. I really appreciate your Knowledge And ideas.