Flicker Problem - Everyone Stumped!

[Justsosolar]

Long story short, I had a system installed that consists of 28 280 watt Itek energy panels with a Solectria 7600tl inverter. 3 strings of 10, 10, and 8. Since day 1 after install, all lighting tied to dimmers flicker badly when dimmed with inverter "on" (not in night mode or manually shut off). Some affected circuits are incandescent, some are LED, some are a mix. I have 2 different types of dimmers (GE, Lutron), both are affected. Flicker is by far the worst when solar output is low, 0-200 watts. It gets increasingly better as solar output increases, and is barely noticeable at output above 5KW. My house was built in 2007 and had no issues prior to the solar; the dimmers and lighting has been there for years.

I can watch the lights flicker and have someone else turn the inverter off and BAM, lights are perfect. I can shut every circuit off in the house aside from one lighting circuit and the solar but there is no improvement (pretty much eliminates external issues). The installers have been out a few times trying to figure out the issue. They adjusted settings, added some ferrites thinking it was interference, but that did not help. Apparently they have another house with a similar issue and replaced the inverter without any improvement, so they hesitate to replace mine. And in case anyone is wondering, they are a very legit installer in this area.

I am (usually) a smart guy, but I cannot figure this out. I google this problem and find almost no information. I searched on this forum but found very little having to do with large systems and flicker. The weirdest part is that just the inverter being on, not even outputting power (because the solar output is too low) causes the flicker. I can't figure out what the inverter would be doing that could cause flicker by just being powered on. Any ideas would be so very appreciated. I am out of them!

[Mike90250]

Power Quality Meter.

Rent one, or find a Utility worker to hook one up for a week


And, simple test, chose a time with the lights flickering, and DC disconnect the inverter. If the flicker stops, it's the inverter. And it's likely your neighbors on the same transformer drop see half the flicker you do.

[truav8r]

I have a flicker issue in my house, but milder and from a slightly different angle. But I'm equally stumped as to the exact cause, so I'll be paying attention to any nuggets of wisdom you find regarding your issue. When I am charging my EV (Leaf) in the garage, I get a minor & temporary flicker on some CFL bulbs in the kitchen and in the master bath. Both sets of lights are on regular rocker switches, on different circuits from each other, and our EV charger (240V) is fed from a subpanel in the garage. The flicker only lasts for a few seconds, and seems to occur only in the first 5 or 10 minutes after plugging in the car. No other lights in the house seem to be affected (mix of CFL, LED, and a few incandescent). We lived in this house for a year before getting the Leaf, and never noticed the flicker before. But interestingly, the flicker also happened in a similar manner when we used the 120V trickle charger that came with the Leaf for a short time before we got the 240V charger. All I can figure is that the Leaf, while modulating the input amps, somehow sends a "reverb" back through the line, but only for a few seconds at an early stage of its charging process. The house is 23 years old, not new but not ancient either.

My solar system is installed as of last week, just waiting on the inspection to flip the ON switch. But now you have me wondering if I'm going to see lights flicker when my pair of SMA inverters are activated. If there is something about the wiring in my house that is sensitive to the EV, perhaps that sensitivity will rear its head with the SMAs too? Guess I'll find out this week.

[sdold]

That last one sounds like excssive voltage drop during the first few minutes of charging, have you measured the voltage to see what it does during the initial charging?

[solarix]

Dimmers use a cheap triac circuit to PWM chop the lighting power to produce dimming. I'd say the chopper is interacting with the stability of the inverter's synchronization to the grid's AC. I guess I'll cross Selectra inverters off the short list of brands I'll use. All those cheap dimmers are noisy SOB's. Only real answer is use and old school variac on your dimmers.

[foo1bar]

Power Quality Meter.

Rent one, or find a Utility worker to hook one up for a week


And, simple test, chose a time with the lights flickering, and DC disconnect the inverter. If the flicker stops, it's the inverter. And it's likely your neighbors on the same transformer drop see half the flicker you do.

Seems like good advice to me.

Also, I'd probably double check all the connections to the grid. Most likely it's just a few - both ends of the connections for the wire from your meter to the main breaker, and all the connections from your meter to the POCO. Can't think of a logical reason they'd cause flickering for your lights due to yoru inverter being on. But I have seen A/C kicking in that caused flickering/light dimming because the connection to the grid had a little higher resistance (and therefore more voltage drop) The POCO would have to be involved to check the connections to your meter and upstream -but you'll want to talk to them anyhow to hook up a power quality meter.

[DanKegel]

How old are those dimmers? If they predate LED bulbs, try popping a new one in. That helped me last year.

[sensij]

I see on the SolarEdge and other string systems I watch that there is a reactive power component that pushes the cos phi significantly away from 1 when the active power generated is low. This is as reported by the inverter and by revenue grade monitoring. I think it is typical for grid tie inverters, at least of the transformerless variety, and not really a Solectria thing. I would agree with others that replacing the dimmers with newer designs is probably the thing to do, at least one to see if it makes a difference.

[foo1bar]

How old are those dimmers? If they predate LED bulbs, try popping a new one in. That helped me last year.

What kind of bulbs are the dimmers connected to?
flourescent? LED? good old tungsten incandescent?
Are the dimmers giving you flickering when they're completely on? Or just when they're doing some dimming?
Usually dimmers have a spot where they're all the way on and they should be acting just like a normal switch.
Are the non-dimmer controlled lights flickering at all? (And are they using the same types of bulbs? (ie. also incandescent or whatever))

[SunEagle]

Power Quality Meter.

Rent one, or find a Utility worker to hook one up for a week


And, simple test, chose a time with the lights flickering, and DC disconnect the inverter. If the flicker stops, it's the inverter. And it's likely your neighbors on the same transformer drop see half the flicker you do.

He wouldn't need to have that PQ meter hooked up more than a day to determine what may be causing the lights to flicker.

If the OP did not have flicker issues with those lights before (especially when you turn the dimmers down real low) than it is more than likely something with a PWM power supply (like the grid tie inverter) causing the issue.

I could do it in less than a day if the OP was within driving distance.

[Sunking]

Many Electronics Do Not Play Well with GTI's. Most GTI are very crude Modified Sine Wave Inverters. Electronic Dimmers and controllers do not work well using MSW. Does not stop there. Try using a regular AM or FM radio and see what happens.

[Naptown]

Many Electronics Do Not Play Well with GTI's. Most GTI are very crude Modified Sine Wave Inverters. Electronic Dimmers and controllers do not work well using MSW. Does not stop there. Try using a regular AM or FM radio and see what happens.

Huh?
I thought a GTI was pure sine not modified sine.

[Sunking]

Huh?I thought a GTI was pure sine not modified sine.

Some are Rich, most are not. Have you looked at any schematics of a GTI?

[Sunking]

Rich sorry to use a link like this, but forum software is toast. Click the following address for pictures of schematics. Note most are Push - Pull Transistor Vibrator circuits and a Transformer output. Make a Square wave on the input of a Line Transformer, and use the transformer to filter out some of the square wave. https://www.google.com/search?q=grid...FccfHgodrXQAIA

[inetdog]

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.