Flicker Problem - Everyone Stumped!

[Justsosolar]

To the extent that the grid can be considered a very low impedance source, the square wave current output of a simple GTI will not directly cause a problem.
But resistance in the house wiring, the service drop and even the utility transformer will turn those sharp edges of the current waveform into matching dips and peaks on the voltage waveform.
That voltage waveform distortion is what most often causes strange behavior from edge-sensitive circuitry like simple line dimmers.
You might be able to get some improvement by beefing up the wiring between the GTI and your main panel, but the service drop and the POCO transformer will still be determining factors.
I have not heard of anyone trying to apply filtering to the GTI output, but in principle it should work.

I am more concerned about the observation that the GTI causes flickering even when you think it is not producing power.

The problems in that case may be a very poorly filtered power supply inside the GTI which is drawing current pulses from the grid or generating high frequency switching noise of its own. An RF filter should take care of that.

Thank you all so much for your suggestions. The installers are still working through this with me. For those who asked about the dimmer quality, I tried new high end dimmers with only a minor change. The dimmers I already had installed were higher end GE/Jasco 12724222 and Lutron MAW-600 (for my still incandescent circuits). And per the original reply to my post, I am working on finding someone with a power quality meter. I did however shut down all circuits except 1 lighting circuit and solar and it still flickers until the DC is disconnected, so we pretty much have isolated it to the inverter.

You mentioned adding a RF filter which is kind of the direction I was looking. I found a company called Cosel that makes these types of filters, but they have so many options it is hard to know which one would be correct. Does anyone have a suggestion on an RF filter?

Again, I really appreciate the support.

[Mike90250]

Your eye can't see flicker past 100Hz, so an RF filter will not help the flicker. Could even be a dud inverter with a couple bad stages that the internal monitoring can't detect.

OR

I had a situation where 240V power wires were not compressed/setscrew not torqued, and there was some arcing causing flicker. Took me a week to track it down.

[SunEagle]

Your eye can't see flicker past 100Hz, so an RF filter will not help the flicker. Could even be a dud inverter with a couple bad stages that the internal monitoring can't detect.

OR

I had a situation where 240V power wires were not compressed/setscrew not torqued, and there was some arcing causing flicker. Took me a week to track it down.

Did you use an infrared camera to find the lose connections or was it just a "pull and yank" exercise?

[Mike90250]

Did you use an infrared camera to find the lose connections or was it just a "pull and yank" exercise?

I was using the IR thermometer in the DC wire box, and heard the arcing in the AC box 3 feet away, it was the jumpers the electrician installed instead of a meter, into the meter socket. They had worked themselves into a spot where they were loose and arcing to their contacts.

[SunEagle]

I was using the IR thermometer in the DC wire box, and heard the arcing in the AC box 3 feet away, it was the jumpers the electrician installed instead of a meter, into the meter socket. They had worked themselves into a spot where they were loose and arcing to their contacts.

I am glad you caught the problem before the arcing destroyed the terminals.

[inetdog]

Your eye can't see flicker past 100Hz, so an RF filter will not help the flicker. Could even be a dud inverter with a couple bad stages that the internal monitoring can't detect.

OR

I had a situation where 240V power wires were not compressed/setscrew not torqued, and there was some arcing causing flicker. Took me a week to track it down.

The RF filter is not to filter out power flucutuations, so the eye threshold of 100Hz does not really come into play.
The goal is to prevent RF or transient spikes on the power line from messing up the electronics of the dimmer, which usually is sensitive both to zero crossings and peak values of the voltage across the dimmer (which is not generally the line voltage.)

Based entirely on theory, a three wire dimmer (using either neutral or ground as a current return for the control circuitry) will perform better with non-resistive loads than a two wire dimmer.

[8.4]

Updates? Not that I have the problem, just like a good mystery solved.

[Justsosolar]

I hate open ended posts too! You never know if the problem was solved or not. Well, good news after many months. Installers swapped the inverter with a different brand and flicker is 99% gone.

Solectria had promised a fix for quite a while, and even flew an engineer out to my house to identify the issue, but never came through (although they did contact me once to say they found the issue and were working on a firmware fix). I'm glad the installers were reputable and took it upon themselves to get this handled. Long story short, if you have lighting circuits on dimmers you may want to stay away from solectria, at least from my experience.