Enlighten me

[mopowr steve]

I’ve been wondering about what effects may be caused, if any; of the inverters used for grid tied systems, more so on the utility side.
For the past couple years I’ve been noticing a problem with what seems to be with a particular power company over another. In that on new construction homes many times we’re having problems with flickering LED bulbs with what appears to be some pattern and random tripping of GFI’s, and arc faults. And in some past discussions on this forum it’s been said that the smart metering and other communications being sent via the electric lines could be the culprit. As the communication is sent near the zero crossing and that it does affect dimmable LEDs as they are reacting to this anomaly. Now if I install a non-dimmable LED that usually remedies the problem.
So, my question is. Is it possible that solar inverters can cause an anomaly on the sign wave like that of communications either as a malfunction of an inverter or in its normal operation as it seeks to sync with the 60HZ ?

 

[Phil Timmons]

Dunno all the present "Grid Sensing" methods, but some used to use a slight freq change to "test" if the grid was present.

This is part of the Anti-Island feature required for UL 1741 automatic disconnect (from the Grid) if Grid power was lost. The inverter would (intentionally) try to step up a little (or down) from 60 Hz, for a couple of cycles and if it could shift the frequency, it would determine the "Real" Grid had been lost, and auto-disconnect for 5 minutes and try again. But never heard of anyone having problems from this. The designs were so detailed they would try to speed up and slow in a balance fashion -- so as not upset an old skool clock that might be around and lose or gain a second or whatever.

Many local substations will have Voltage Level shifts at something like 7 am and 7 pm (usually done with Automatic Tap Changes on the Medium Voltage Transformers) to try to keep Voltage Levels steady through out the day and night. If you have power quality meter recording equipment on a site, you can often "see" it happen, but that does not usually trip Arc or GFI equipment downstream, either.

We do see "noise" from AC line Control and Communications on some micro-inverter systems. Enphase Micro-Inverters, for example use this system to monitor each inverter and report production. Some folks that have (or have not -- not doing this battle) "EMF Sensitivity" have some concerns about that -- so we disconnect the control signal generator in the combiner box, and that makes them and their EMF Meters happy.

 

[ramsy]

For the past couple years ..we’re having problems with ..random tripping of GFI’s, and arc faults

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[jaggedben]

Anti-islanding algorithms are proprietary trade secrets so good luck getting any confirmation if that is contributing to anything or not. Anything is possible but I'm fairly skeptical that they would cause the problem you mention. Too many solar installations under my belt with no one complaining of this problem.

 

[pv_n00b]

AFCI in general has been the bane of many an electrician's job. I don't know if PV inverters make the existing problems worse and I have not heard of any verified problems. Generally, if a PV system is installed and the customer's toaster dies a week later it was the fault of the PV system.

 

[ggunn]

AFCI in general has been the bane of many an electrician's job. I don't know if PV inverters make the existing problems worse and I have not heard of any verified problems. Generally, if a PV system is installed and the customer's toaster dies a week later it was the fault of the PV system.

Yeah, we have a customer who is trying to blame the failure of an HVAC unit on "power surges" from the PV system we installed a couple of years ago. Never mind that a PV inverter cannot produce "power surges" and the egauge monitoring we installed shows nothing out of the ordinary.

 

[mopowr steve]

Dunno all the present "Grid Sensing" methods, but some used to use a slight freq change to "test" if the grid was present.

This is part of the Anti-Island feature required for UL 1741 automatic disconnect (from the Grid) if Grid power was lost. The inverter would (intentionally) try to step up a little (or down) from 60 Hz, for a couple of cycles and if it could shift the frequency, it would determine the "Real" Grid had been lost, and auto-disconnect for 5 minutes and try again. But never heard of anyone having problems from this. The designs were so detailed they would try to speed up and slow in a balance fashion -- so as not upset an old skool clock that might be around and lose or gain a second or whatever.

Many local substations will have Voltage Level shifts at something like 7 am and 7 pm (usually done with Automatic Tap Changes on the Medium Voltage Transformers) to try to keep Voltage Levels steady through out the day and night. If you have power quality meter recording equipment on a site, you can often "see" it happen, but that does not usually trip Arc or GFI equipment downstream, either.

We do see "noise" from AC line Control and Communications on some micro-inverter systems. Enphase Micro-Inverters, for example use this system to monitor each inverter and report production. Some folks that have (or have not -- not doing this battle) "EMF Sensitivity" have some concerns about that -- so we disconnect the control signal generator in the combiner box, and that makes them and their EMF Meters happy.

The phenomenon of particularly the flickering LED bulbs in this fashion is kinda a new thing that’s been occurring just the past couple years. Some of the changes in recent times is the installation of smart meters, and seeing more solar farms tied into the grid (the reason for my asking). I did have the POCO come out to one of the job sites a couple years ago with no solution to the problem. We removed smart meter—— no improvement. Turn off all branch circuits but one to see if it’s internal—-no improvement. So it seems I need a higher trained power quality individual to help determine what is going on.
One common denominator that I can tell is that the problems seem to be related to one particular power company over another. I have 3 jobs, all about 25 miles from each other but have the same POCO and experience the same phenomenon. So is it a communication issue, or some thing on the primary feeding their entire system, or as my question, some kind of “noise” caused by solar farm or even wind turbine?

 

[pv_n00b]

The phenomenon of particularly the flickering LED bulbs in this fashion is kinda a new thing that’s been occurring just the past couple years. Some of the changes in recent times is the installation of smart meters, and seeing more solar farms tied into the grid (the reason for my asking). I did have the POCO come out to one of the job sites a couple years ago with no solution to the problem. We removed smart meter—— no improvement. Turn off all branch circuits but one to see if it’s internal—-no improvement. So it seems I need a higher trained power quality individual to help determine what is going on.
One common denominator that I can tell is that the problems seem to be related to one particular power company over another. I have 3 jobs, all about 25 miles from each other but have the same POCO and experience the same phenomenon. So is it a communication issue, or some thing on the primary feeding their entire system, or as my question, some kind of “noise” caused by solar farm or even wind turbine?

The only way to get to the bottom of it is to put a recording PQ meter on the service and go through the data.

 

[GoldDigger]

The only way to get to the bottom of it is to put a recording PQ meter on the service and go through the data.

Will any common PQ meter log both short (sub cycle) spikes and superimposed RF energy?

 

[ramsy]

Will any common PQ meter log both short (sub cycle) spikes and superimposed RF energy?

Can you switch blinking lights between POCO, inverter, battery, or generator?

 

[pv_n00b]

Will any common PQ meter log both short (sub cycle) spikes and superimposed RF energy?

Sub-cycle spikes should not be a problem within the limits of a meter, check the specs. RF energy is not a PQ related problem, that's a whole other area. PQ is about waveform shape, THD, and transients.

 

[mopowr steve]

Sub-cycle spikes should not be a problem within the limits of a meter, check the specs. RF energy is not a PQ related problem, that's a whole other area. PQ is about waveform shape, THD, and transients.

Say, it is an RF issue. Who and how do I get any resolution to a problem if this would be the case?

 

[pv_n00b]

Say, it is an RF issue. Who and how do I get any resolution to a problem if this would be the case?

Probably have to bring in an RF engineer and spend a lot of money on a study. You get a report saying there is RF energy in the system because there will be. The question is, is the RF energy out of tolerance? If it's inside the tolerance and the LEDs still flicker due to the RF then it's poor LED driver design. Someone at this point has spent a lot of money just to find out they should have bought better LED lighting. I would feel like there is a great chance of going down a rat hole on this and I would try different LED lighting first.

 

[mopowr steve]

Probably have to bring in an RF engineer and spend a lot of money on a study. You get a report saying there is RF energy in the system because there will be. The question is, is the RF energy out of tolerance? If it's inside the tolerance and the LEDs still flicker due to the RF then it's poor LED driver design. Someone at this point has spent a lot of money just to find out they should have bought better LED lighting. I would feel like there is a great chance of going down a rat hole on this and I would try different LED lighting first.

Yes, but if it’s going to be a common phenomenon to have to go and run around to different suppliers to find LED bulbs that deal with this s...t it’s as waist full of time akin to arc fault breakers troubleshooting when there is no apparent problem.

 

[wwhitney]

So, my question is. Is it possible that solar inverters can cause an anomaly on the sign wave like that of communications either as a malfunction of an inverter or in its normal operation as it seeks to sync with the 60HZ ?

Sounds like you have no evidence or reason to link the observed phenomenon with PV inverters.

Cheers, Wayne

 

[ggunn]

So, my question is. Is it possible that solar inverters can cause an anomaly on the sign wave like that of communications either as a malfunction of an inverter or in its normal operation as it seeks to sync with the 60HZ ?

There is no way to answer that question; proving that something like that is impossible is, in and of itself, impossible. That fact is absolutely in no way evidence that it is in fact possible.

 

[pv_n00b]

Yes, but if it’s going to be a common phenomenon to have to go and run around to different suppliers to find LED bulbs that deal with this s...t it’s as waist full of time akin to arc fault breakers troubleshooting when there is no apparent problem.

There is nothing common about this. There is no evidence that this is going to become a common phenomenon.

 

[mopowr steve]

well I hope more people chime in experiencing the same problem or decide to delve into further than just gremlins or do nothing about it.

 

[pv_n00b]

well I hope more people chime in experiencing the same problem or decide to delve into further than just gremlins or do nothing about it.

I remember maybe a decade ago there was a big problem with an inverter interfering with garage door openers. It happened a lot, it was pretty easy to trace to the inverter, and the manufacturer fixed the problem. So if you can get enough people involved, you can identify a specific problem, and you can definitively trace that problem to a device you can probably get it fixed.