Lv6548 LED Light flicker

[medic149]

I have reviewed most of the threads on this topic, but unable to find an answer.

I have an LED shop light plugged in directly to the AC output and getting flickering every 1 to 1.5 seconds.

Setup:

1 lv6548
2 EG4-LL 48v batteries
30 amp panel in cabin directly from the LV6548

Turned off PV input, running only on batteries and no change in flicker.

Turned off batteries but not enough solar coming in to run. Lv6548 shut down AC output. Turned batteries back on and flicker still there but way less noticeable. In fact, while I am typing this flicker is only once in awhile now with no decrernable pattern. Will try again when there is enough solar to run directly without batteries.

In the meantime, does anyone have any thoughts?

There is a slight flicker occasionally in the cabin lights, but never too bad.

Thank you in advance!

 

[Zwy]

Where is the N-G bond?

Is the PV array grounded to the main panel?

 

[bones1]

Where is the N-G bond?

Is the PV array grounded to the main panel?

Should the PV array be grounded to the main panel, mine has a separate ground rod out in the yard. I want it to be correct, Thanks. Also waiting to hear about your inverter issues as well. Mine flickers and voltage on only one 6500 fluctuates like in your video

 

[Zwy]

Should the PV array be grounded to the main panel,

Yes, EGC should be ran from PV array to the main panel or ground rod at the main panel. https://diysolarforum.com/threads/good-video-on-pv-grounding.63242/#post-788104

mine has a separate ground rod out in the yard.

Allowed but not needed. But it does need a EGC back to the main panel.

I want it to be correct, Thanks. Also waiting to hear about your inverter issues as well. Mine flickers and voltage on only one 6500 fluctuates like in your video

I did not get inverters swapped yesterday and might not get it done today either. The LV6548's don't have this problem on my system.

 

[RCinFLA]

Most flickering is due to poor PWM filtering/inverter feedback regulation stability design.

PWM sinewave L-C filter becomes very underdamped with ringing when under small AC loads. A constant resistive load is not a problem but sudden changes in AC output current load can trigger PWM filter ringing.

Many power supplies, including LED AC to DC conversion, have simple rectifier-filter capacitor, with high current crest factors (poor resulting AC power factor) where the power is transferred in short bursts of current at voltage peaks of AC sinewave,

Worst case ringing of PWM sinewave filter is when a load is switched off just as the AC sinewave passes its peak voltage of sinewave. This triggers a severe ringing of the PWM L-C filter that must be compensated by AC output voltage regulation within the feedback loop of inverter and some snubber dampening of L-C filter.

The ringing is due to the filter inductor having built up current with stored energy, then when load is switched off there is no place to dump the inductor's stored energy, so it rings, trading current back and forth with the filter output capacitor. This drives the inverter AC output voltage regulation crazy trying to compensate for the typically 3 kHz to 4 kHz filter corner cutoff frequency ringing causing instability of inverter 50/60 Hz AC output voltage regulation.

If you also plug in a moderate resistive load, like a toaster, the flickering will likely go away.

A company that just copies the design of another inverter, like many of Chinese inverters, may not understand the subtle design requirements of the PWM sinewave filter. What appears to be minor part substitutions in the inverter can have a large impact on the performance of PWM filter and the inverter's AC output voltage regulation stability.

Often the filter inductor is selected to soft saturate its core at high load current to limit the amount of stored energy. This is very subtle and not easily determined by just measuring inductor on an impedance meter.

If the ringing gets really bad it can damage plugged in devices and even the inverter switching devices.

Inverter firmware can change the AC output voltage regulation feedback response digital filtering which may improve the situation of it becoming too unstable.

 

[bones1]

Sounds like there will be a whole lot of rma's coming to Signature Solar.

 

[Gavin Stone]

Sounds like there will be a whole lot of rma's coming to Signature Solar.

There were at one point I believe. Apparently based off what James said firmware helped some units. Others has to be replaced. Seems like they may have gotten it under control now. Mpp’s and sungold models have been hitting the market with some of the same issues now. Something to do with a factory hardware change around October or November of last year.

Which explains why people with the earlier versions of the eg4’s didn’t have those problems.

 

[Zwy]

Most flickering is due to poor PWM filtering/inverter feedback regulation stability design.

Yes, the inverter output regulation goes awry, I have a video with the output voltage swinging between 112V to 128V.

PWM sinewave L-C filter becomes very underdamped with ringing when under small AC loads. A constant resistive load is not a problem but sudden changes in AC output current load can trigger PWM filter ringing.

Many power supplies, including LED AC to DC conversion, have simple rectifier-filter capacitor, with high current crest factors (poor resulting AC power factor) where the power is transferred in short bursts of current at voltage peaks of AC sinewave,

Worst case ringing of PWM sinewave filter is when a load is switched off just as the AC sinewave passes its peak voltage of sinewave. This triggers a severe ringing of the PWM L-C filter that must be compensated by AC output voltage regulation within the feedback loop of inverter and some snubber dampening of L-C filter.

The ringing is due to the filter inductor having built up current with stored energy, then when load is switched off there is no place to dump the inductor's stored energy, so it rings with the filter output capacitor. This drives the inverter AC output voltage regulation crazy trying to compensate for the typically 3 kHz to 4 kHz filter corner cutoff frequency ringing causing instability of inverter 50/60 Hz AC output voltage regulation.

If you also plug in a moderate resistive load, like a toaster, the flickering will likely go away.

I had some resistive heaters in the house this spring. Lights strobing, flip on a heater and it would go away. Even turning on more lights would sometimes cause the strobe to end.

I had scoped N to G at the loads panel and found ringing in the voltage ranging up to 7V. Your post makes perfect sense why I was seeing this.

A company that just copies the design of another inverter, like many of Chinese inverters, may not understand the subtle design requirements of the PWM sinewave filter. What appears to be minor part substitutions in the inverter can have a large impact on the performance of PWM filter and the inverter's AC output voltage regulation stability.

I believe this is has occurred, hardware was changed and resulted in this problem.

If the ringing gets really bad it can damage plugged in devices and even the inverter switching devices.

One member told me privately his TV is now fried after replacing the 6500EX's he had with replacements. Light strobe still present also.

 

[bones1]

I just checked mine both are on March 22. I have the new firmware installed and both bonding screws removed and I have most if not all of the problems that you see mentioned on the forum. Random shut-offs when batteries are 100% and good solar coming in, bad light flickering, and the 90-volt pv input sticking until I reset the pv switch. Your rma fixed the issues so I will have to start that process I suppose. Any tips?
I am watching your videos on the new 18K install and will follow you to see if that unit is any good.

 

[Gavin Stone]

I just checked mine both are on March 22. I have the new firmware installed and both bonding screws removed and I have most if not all of the problems that you see mentioned on the forum. Random shut-offs when batteries are 100% and good solar coming in, bad light flickering, and the 90-volt pv input sticking until I reset the pv switch. Your rma fixed the issues so I will have to start that process I suppose. Any tips?
I am watching your videos on the new 18K install and will follow you to see if that unit is any

Yeah I would contact them to see, but sounds like a candidate for RMA. When You updated the firmware did the units rev up?

 

[bones1]

Yes sir, they did rev up. That means the firmware took correct?.

 

[Gavin Stone]

Yes sir, they did rev up. That means the firmware took correct?.

It doesn’t say that on the literature. But I’m thinking so. I had one time where they didn’t. So I reinstalled it.

 

[Skypower]

I’m thinking that some of those units that the software updates didn’t cure were probably made during the Covid crunch. Part substitutions were made and didn’t work out so well. Sucks for everyone ,retailers and consumers alike.

 

[khaledme]

This thread started with MPP LV6548 then the discussion changed to EG4 6500EX which is a different product though it looks similar. Can someone clarify?

 

[Gavin Stone]

The various 6500 units are all made by voltronic. They just have some mild differences depending on the brands.

 

[khaledme]

The various 6500 units are all made by voltronic. They just have some mild differences depending on the brands.

MPP LV6548 does not seem to heave the same issues as EG4 version. They are all made by Voltronics but they have differences in software, and possibly hardware.

 

[Gavin Stone]

MPP LV6548 does not seem to heave the same issues as EG4 version. They are all made by Voltronics but they have differences in software, and possibly hardware.

Differences in software and hardware yes. And my lv6548’s didn’t have the same issues. But towards the beginning of this year I started hearing about similar issues with the mpp versions. And I’ve talked with multiple people that have had problems with the sungold versions.

 

[khaledme]

Differences in software and hardware yes. And my lv6548’s didn’t have the same issues. But towards the beginning of this year I started hearing about similar issues with the mpp versions. And I’ve talked with multiple people that have had problems with the sungold versions.

Thanks for the clarification. I just got mine in preperatin for my solar system ( Sept 2022 production ). How long have you had your LV6548 and what is your experience with it so far.

 

[Gavin Stone]

Thanks for the clarification. I just got mine in preperatin for my solar system ( Sept 2022 production ). How long have you had your LV6548 and what is your experience with it so far.

I bought a pair of the lv’s in early 2022. They worked great for around 10 months while I used them. I changed to eg4 6500’s for the higher voc limits. My lv’s were hitting their 250v limit in the cold weather. Over all I was impressed with the Lv6548’s. They are sorta noisy. But they get the job done.

The eg4 6500’s I upgraded to had issues with light flicker. I had to return them. Signature Solar sent me a new pair to review on my channel which had an issue with an f80 error. The third pair they sent were awesome. They were essentially just like my Lv’s I had earlier but with higher voc.

 

[khaledme]

I bought a pair of the lv’s in early 2022. They worked great for around 10 months while I used them. I changed to eg4 6500’s for the higher voc limits. My lv’s were hitting their 250v limit in the cold weather. Over all I was impressed with the Lv6548’s. They are sorta noisy. But they get the job done.

The eg4 6500’s I upgraded to had issues with light flicker. I had to return them. Signature Solar sent me a new pair to review on my channel which had an issue with an f80 error. The third pair they sent were awesome. They were essentially just like my Lv’s I had earlier but with higher voc.

Thanks for the feedback. What is the name of your channel?
MPP solar has a new version LV6548V which has 390V PV input. I have seen someone review them on youtube, they seem to have higher ldle consumption with more fan noise as well.
The one I bought is the regular LV with 250V Max PV, which should be okay for my application. I plan on having 2 strings of PV about 130V each string.