Help troubleshooting flickering/dimming lights

ssean

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Aug 1, 2020
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This is more of a general electrical question, but I'm hoping someone may be able to help.

I've been experiencing issues with ceiling lights flickering/dimming when I use a high powered appliance. (Microwave, toaster over, washing machine, etc.)

1. The lights that are being affected are on different circuits then the appliances.
2. Not all lights in the home are affected.
3. This issue has been present PRIOR to our solar system being installed.
4. I'm running two Deye 8k inverters in parallel in grid tied mode.
5. If I turn off the breaker (that provides grid power to the inverters) and run only on PV and batteries, the problem is eliminated.
6. If I leave the breaker on (that provides grid power to the inverters) and run only on batteries and PV, the problem persists, even when power is not being pulled from the grid.

Can anyone help me shed some light on this? A local electrician said it could be a loose neutral wire from the meter to the street.

I'm confused why turning off the breaker for the grid input solves the issue, but leaving the grid connection on and running from batteries does not.

Thanks in advance for any help.
 

DThames

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I am not familiar with the Deye 8k inverter. You said, "grid tied", are you feeding power back to the grid? Also, when the breaker to the grid is on, is the inverter acting like a U.P.S. where it is "on" but you are running off of grid power?

Since the problem existed before your solar install, does the solar install include the Deye 8k inverters or were they in place running off a battery before solar install?

If you are running off the grid and this problem was present before the inverters, then I would suspect your grid power is seeing voltage sags when you pull higher power loads. Do you have a way to monitor your AC voltage under the problem conditions?
 

rhino

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Part of the problem may be the cables are undersized for the load and distances and there is drop in voltage when those larger items turn on. What is distance from the utility supplied transformer outside and gauge of wire coming in from utility to your electric panel? I am however confused by what you see in #6.
 

mrzed001

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I'm confused why turning off the breaker for the grid input solves the issue, but leaving the grid connection on and running from batteries does not.

Does this breaker break the Neutral cable too ? So do it break the Neutral-ground bond ?

Did you test if there is a working PE-N relay in the Deye inverter ?
PE-N_out and PE-L-out Volt when only Ground is connected to the inverter AC_in side ?
 

ssean

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I am not familiar with the Deye 8k inverter. You said, "grid tied", are you feeding power back to the grid?

Yes, the inverters send back excess PV power to the grid and will also pull power from the grid as needed.

Also, when the breaker to the grid is on, is the inverter acting like a U.P.S. where it is "on" but you are running off of grid power?

When the breaker is on, it's providing the inverter with the option to use grid power. For example, if the load exceeds what is currently being generated from the panels, and the batteries are dead, it will pull power from the grid to supply the load.

Since the problem existed before your solar install, does the solar install include the Deye 8k inverters or were they in place running off a battery before solar install?

Everything was installed at the same time. The issue was present when we were connected to the grid only, which leads me to believe it's related to the home wiring or the power companies wiring.

If you are running off the grid and this problem was present before the inverters, then I would suspect your grid power is seeing voltage sags when you pull higher power loads. Do you have a way to monitor your AC voltage under the problem conditions?

I can monitor the grid voltage though the inverters. The grid volatge usually hovers around 230V.
 

DThames

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If the light is an incandescent type, do you also see this dimming and flickering? Can you put a meter at the same point of connection as a light that is dim? For example, a power strip with a light and the meter on the power strip. It does sound like some type of house wiring issue.
 

ssean

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If the light is an incandescent type, do you also see this dimming and flickering? Can you put a meter at the same point of connection as a light that is dim? For example, a power strip with a light and the meter on the power strip. It does sound like some type of house wiring issue.

One of the lights is a Philips LED bulb, and the other two are ceiling fan lights, which I believe are CFL bulbs.

With the grid breaker ON - The voltage drops from 115V to 90V when the microwave is turned on.
With the grid breaker OFF - I will report back shortly.
 
Last edited:

camelCase

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Apr 24, 2021
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How old is your house? Have you tried testing other circuits for the same behavior, ie plugging a lamp into various outlets? Voltage drops on separate circuits make me think the problem is with the mains somewhere. Perhaps poor connections in the panel or with the service line.

I would have an electrician come check it out.

We once lost all the magic smoke from the TV when the line at our power pole developed a bad connection. Voltage to the whole house sagged badly, so the current spiked through some circuit in the TV even though it was off.
 

12VoltInstalls

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6. If I leave the breaker on (that provides grid power to the inverters) and run only on batteries and PV, the problem persists, even when power is not being pulled from the grid.

Can anyone help me shed some light on this? A local electrician said it could be a loose neutral wire from the meter to the street.

I'm confused why turning off the breaker for the grid input solves the issue, but leaving the grid connection on and running from batteries does not.
@timselectric

Since it is grid specific and when grid is locked out it goes away then you know it’s grid related- either a neutral issue as alluded to or something is backfeeding
 

timselectric

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It could just be a loose connection. But, i would expect it to progressively get worse and reveal itself by now. If this has been going on for a while.
 

ssean

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I just ran a few more tests with the grid breaker ON.

I'm experiencing the following behavior:

When I turn on the microwave, the circuits with the dimming lights:
110V -> 91V

When I turn on the microwave, other unaffected outlets in the home:
125V -> 145V

The affected circuits are normally @ 110V and drop to 91V when the microwave is turned on.

The unaffected circuits are normally @ 125V and increase to 145V when the microwave is turned on.
 

timselectric

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I would try to follow the voltage drop, by checking in several places along the path of the current flowing to the microwave. When you stop seeing the drop, you can narrow down the problem location.
If it continues through the service, then it's possibly a connection at the grid. (Pole or pad mount connection)
 

timselectric

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I just ran a few more tests with the grid breaker ON.

I'm experiencing the following behavior:

When I turn on the microwave, the circuits with the dimming lights:
110V -> 91V

When I turn on the microwave, other unaffected outlets in the home:
125V -> 145V

The affected circuits are normally @ 110V and drop to 91V when the microwave is turned on.

The unaffected circuits are normally @ 125V and increase to 145V when the microwave is turned on.
That's a floating neutral imbalance.
 
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