Flickering lights

[Mjtenney]

I put together this system according to plans on the website. For some reason, the overhead shed lights flicker whenever the sun is out. They work find when I disconnect the charge controller or the sun is down. Does anyone know if this is a problem with the inverter or the solar charge controller? Or maybe the lights?

 

[Bud Martin]

Are they LED or incandescent lights?
"They work find when I disconnect the charge controller or the sun is down" If that is the case then the inverter is OK since it works fine without controller connected. BTW, did you disconnect the SCC output to the battery after you disconnect the PV panel first?
Do you see the Battery Voltage display on the SCC going up and down when the light is flickering?
What other loads connected to the AC output of the inverter?
What is that black box to the right of the SCC?
BTW, I have the same inverter for my system.

 

[mike95490]

As the solar charge controller manages the battery voltage, it's going to vary, and that's likely the source of the flicker.

 

[Bud Martin]

When charger in CC mode, the Voltage will be varied to maintain constant current through the load, when it is in CV mode then the Voltage will be maintained at constant Voltage and current will be varied so the load will see constant Voltage..

 

[Mjtenney]

Are they LED or incandescent lights?
"They work find when I disconnect the charge controller or the sun is down" If that is the case then the inverter is OK since it works fine without controller connected. BTW, did you disconnect the SCC output to the battery after you disconnect the PV panel first?
Do you see the Battery Voltage display on the SCC going up and down when the light is flickering?
What other loads connected to the AC output of the inverter?
What is that black box to the right of the SCC?
BTW, I have the same inverter for my system.

All I did to disconnect was flip the breaker. They are LED lights. The voltage seems consistent, the load fluctuates a lot more when the SCC is connected. There are no other loads currently. Just 124 watts for the lights. The other black box is the inverter for my landscape lights.

 

[Mjtenney]

When charger in CC mode, the Voltage will be varied to maintain constant current through the load, when it is in CV mode then the Voltage will be maintained at constant Voltage and current will be varied so the load will see constant Voltage..

Thanks Bud. You’re talking to an idiot though. What’s Cc and CV mode?

 

[svetz]

TLDR: Probably a combination of the SCC frequency and Inverter frequency

...There are no other loads currently. Just 124 watts for the lights.

That doesn't make sense to me with this:

The voltage seems consistent, the load fluctuates a lot more when the SCC is connected.

So how is the load fluctuating if it's constant?


So... thinking out loud....

Why do LED lights flicker?
AC power is a sine wave; it's going on/off 50 or 60 times per second depending on your supplier's frequency (e.g., in the US it's 60 Hz).
Powering an incandescent bulb that's no issue as its heat that makes the light and the heat rides through the on/off cycles.

LEDs have no similar persistence, they seem to be consistently on because that frequency is typically fast enough the eye can't perceive the difference.

LEDs change brightness based on changing power (i.e., brighter if voltage/current goes up). A change in power with frequency can cause them to pulsate, which is different from flickering (a noticeable off state).

the overhead shed lights flicker whenever the sun is out.

LEDs connected to DC power don't flicker. So, if your LEDs are flickering or pulsating I'm going to go out on a limb and say they're AC-powered. Switching them to DC should eliminate any flickering.

• If they're flickering, something is happening to the AC frequency such that it's either reduced or varying to where you can notice it. That would indicate some sort of inverter issue. Probably not the case as other stuff would fail.
• If they're pulsating, something is happening to the AC power and that could be a few things.

If you have a cell phone camera I'd say capture video of it working and not-working and compare the frames. If you have a friend with an oscilloscope, they can definitely tell you what's going on.

They work fin[e] when I disconnect the charge controller or the sun is down.

Solar Charge Controllers (SCC) take the power from the panel and direct it into the battery. Like any battery charger, they charge the battery by supplying current at a voltage higher than the battery voltage. There are also typically multiple charge stages, but we can ignore that for now.

A Pulse Width Modulated (PWM) SCC operates by flipping on-off at a variable frequency as needed to properly charge the battery. So, the charging voltage on such a system is changing between 14.1 and 10.5 V depending on the charge in the battery. A good quality PWM should minimize the output fluctuation with a capacitor.

Inverters are generally pretty good about keeping the frequency constant. Typically as the source (battery) voltage drops they up the current to keep the output power constant; but the AC voltage does fall in accordance with input voltage. Good quality inverters with big capacitors probably wouldn't notice rapid changes in the input from a PWM.

If the SCC voltage is varying between 14.1 and 10.5, then that's the voltage the inverter sees. So the output voltage is probably going up and down too. A digital meter won't see any sort of fluctuation as it is averaging multiple cycles rather individual waveforms. Applying an additional load might also make them stop appearing to flicker as it'll bring the inverter voltage down.

But, I could see where the frequency output of the inverter could have a harmonic frequency with the SCC that caused the LEDs to appear to pulsate. Probably nothing to worry about electrically. I'm not sure if switching your SCC to an MPPT would make a difference or not, I seem to recall someone saying MPPTs used PWM on the output too.

Possibly a capacitor between the battery and the SCC (or inverter) to stabilize the input voltage? One of the EEs could probably tell you for sure (@BiduleOhm?)

 

[BiduleOhm]

TLDR: Probably a combination of the SCC frequency and Inverter frequency

It can also be the higher voltage during charge (LA battery...) changing the inverter operating point making it unstable (cheap chinese inverter...) especially since it seems to be loaded only by LED lamps (with usually very poor PF) if I understood the OP correctly.

Possibly a capacitor between the battery and the SCC (or inverter) to stabilize the input voltage?

It might but the inverter should already have quite a big capacitor bank. Usually the goal when adding capacitors is to use supercaps to avoid the inverter putting ripple on the battery, BMS, etc...

I think the problem is in the inverter here, it should not be unstable, whatever the SCC does in normal operation.

//

Questions for the OP:

Is there only LEDs lamps currently connected to the inverter?

Can you try adding a 1 to 2 kW resistive load (halogen lights, toaster, heat gun, heater, ...) when the problem is present to see if it suppresses it?

Can you try charging the battery with a classic car charger with the SCC disconnected to see if it recreates the problems?

Is the inverter a HF or LF one?

What's "flicker" exactly in your case? do they blink? dim? flicker regularly? irregularly? other?


NB: ideally you would power 12 V LEDs lamps directly from the battery so you can avoid the inverter losses (and not loading it with very low PF loads as a bonus).

 

[billynoah]

It can also be the higher voltage during charge (LA battery...) changing the inverter operating point making it unstable (cheap chinese inverter...) especially since it seems to be loaded only by LED lamps (with usually very poor PF) if I understood the OP correctly.




It might but the inverter should already have quite a big capacitor bank. Usually the goal when adding capacitors is to use supercaps to avoid the inverter putting ripple on the battery, BMS, etc...

I think the problem is in the inverter here, it should not be unstable, whatever the SCC does in normal operation.

//

Questions for the OP:

Is there only LEDs lamps currently connected to the inverter?

Can you try adding a 1 to 2 kW resistive load (halogen lights, toaster, heat gun, heater, ...) when the problem is present to see if it suppresses it?

Can you try charging the battery with a classic car charger with the SCC disconnected to see if it recreates the problems?

Is the inverter a HF or LF one?

What's "flicker" exactly in your case? do they blink? dim? flicker regularly? irregularly? other?


NB: ideally you would power 12 V LEDs lamps directly from the battery so you can avoid the inverter losses (and not loading it with very low PF loads as a bonus).

I'm having a similar issue to the OP and noticed the flicker does indeed go away with a 1500W resistive load (electric kettle). What does that tell you?

The inverter is a Sol-Ark 12k (60/50Hz). In my case the light is "pulsating" with a regular rhythm. I've tried completely shutting off PV and Battery and the pulsating changes (slows down). The light in question is a dimmable LED connected to a LeGrand dimmer. The problem just suddenly appeared after approx 1 month on this inverter.

 

[BiduleOhm]

It tells me that the inverter is probably not super stable with a low power load and/or a mostly non-resistive load.

But since you're using a dimmer the problem might be here instead. Did you try with the dimmer at 100 %?

 

[billynoah]

It tells me that the inverter is probably not super stable with a low power load and/or a mostly non-resistive load.

But since you're using a dimmer the problem might be here instead. Did you try with the dimmer at 100 %?

Yes - oddly the light flickers only at 100% but is stable at lower settings. And I just discovered another important factor: the light pulsating was happening due to another dimmer switch in the house being on and dimmed half way. When this second dimmer is off or turned all the way up, the bathroom light stops pulsating. So the two dimmers are somehow interacting.

This is all way over my head but I'd really like to understand why two dimmers would interact in a way that makes one or the other unstable.

 

[MrM1]

My dimmer does that to LED lights

Also my LED lights will pulse to the beat of the Washing machine

 

[BiduleOhm]

This is all way over my head but I'd really like to understand why two dimmers would interact in a way that makes one or the other unstable.

Probably because of conducted noise. Unless you start doing tests while having an oscilloscope taking some measurements of what is happening you can't really pinpoint the exact cause. NB: never connect an oscilloscope to mains referenced stuff if you don't know exactly what you're doing.

Also, most LED lamps aren't dimmable so that may also be a factor in what is happening here. If you want to be able to dim them you need lamps that specifically say they are dimmable, otherwise it might work but more often than not it will not work.

 

[12VoltInstalls]

I'd really like to understand why two dimmers would interact in a way that makes one or the other unstable.

You were looking at the symptom, and the things that affect it, but you were not looking at the causation.
If I were evaluating your system according to the details that you’ve put out here I would say that the capacitive resistance of various dimmer settings is revealing a pulsing input from your solar charge controller. The variable inductive load experienced by another poster with his washing machine is essentially a similar but different behavior. It still will create pulsing.

Are these 120V LEDs or 12V?
I’d bet the inverter is wavering off center slightly from the energy input of the SCC.

A second possibility is just the fact that certain waveforms at 120 V even on grid power can make the voltage conversion in LED lights create a flicker. Not a good idea: but in apartment rentals I figured out that sometimes reversing H and N on the fixture would stop the flicker but I never left it that way because it didn’t seem like a good idea

 

[billynoah]

you need lamps that specifically say they are dimmable

Thanks, yes my lamps are all dimmable. I wouldn't wire non-dimmable lamps to a dimmer.

Are these 120V LEDs or 12V?

Have no idea. This is a Panasonic vent fan - the light is described as "10-Watt dimmable LED chip panel".

I feel this is less of a problem now that I know that this only happens when two dimmers are in very specific positions.

 

[BiduleOhm]

I wouldn't wire non-dimmable lamps to a dimmer.

I've tried just for fun...? but yea, 95 % of the time they don't work (or work but with a very bad flicker).

 

[12VoltInstalls]

Have no idea. This is a Panasonic vent fan - the light is described as "10-Watt dimmable LED chip panel"

Does it use inverter power or 12V?
Almost 100% it’s 120V and that is probably part of it.

‘Regular’ LEDs convert 120VAC to DC. I’ve read it’s done in one of three ways- basic diode and resistor; a more complex (but cheap) circuit; and a more advanced circuit board that regulates output (dimmable but not always). It seems that each to varying degrees can be effected by inductive loads in the house, or - where I saw it most- from the neighbors in an apartment building, or in a building with 150 offices.

Interesting that these are all inexpensive lighting with low wattage- the RAB wall packs and interior hall lighting were expensive and didn’t seem to ever flicker. But they were much higher wattage- and I don’t know if the high watts or the quality make them flicker free.

 

[WYtreasure]

The guy has been gone since June

 

[Hedges]

Thanks, yes my lamps are all dimmable. I wouldn't wire non-dimmable lamps to a dimmer.

I've tried just for fun...? but yea, 95 % of the time they don't work (or work but with a very bad flicker).

Maybe make an exception in this case, and see what happens with non-dimmable (just keep your dimmer turned up all the way.) Dimmable is supposed to vary in intensity with chopped AC. If output from inverter warbles, it obliges. So maybe non-dimmable will suck extra juice trying to maintain constant output. Maybe a premium/name brand. I think it was CFL that rode through voltage variations due to my electric furnace, while a different type (incandescent) dimmed.

I did try some dimmable LED once, in a range hood. I didn't like the flicker, now using incandescent. The things are supposed to deliver steady dimmed light, not follow every clipped cycle! Might need a bigger capacitor.

 

[12VoltInstalls]

The guy has been gone since June

Umm. woops- talking to ghosts