Inverter stuck voltage on PV string

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name_less

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I have 8kW Deye inverter and noticed today that one of the PV string voltage got stuck (circled in yellow), but once I cycled the circuit breaker to the string it recovered (circled in green).

Looking back at historic data this is the third time this has happened.

What could be cause of this?

1720716573119.png
 
name_less said:
I have 8kW Deye inverter and noticed today that one of the PV string voltage got stuck (circled in yellow), but once I cycled the circuit breaker to the string it recovered (circled in green).

Looking back at historic data this is the third time this has happened.

What could be cause of this?

View attachment 1739099
Click to expand...
What voltage is this, and what happened to the current during this time?
 
It was still producing current, even with the constant (stuck) voltage. The voltage was flat lined until I cycled the PV2 circuit breaker.

I have attached two figures, before and after the cycling of the PV2 circuit breaker.

It seems as if the MPPT for the inverter clipped the voltage, because of the clipping of voltage I missed out on some additional solar production I could've gained.

1720727138169.png

1720727155602.png
 
name_less said:
It was still producing current, even with the constant (stuck) voltage. The voltage was flat lined until I cycled the PV2 circuit breaker.

I have attached two figures, before and after the cycling of the PV2 circuit breaker.

It seems as if the MPPT for the inverter clipped the voltage, because of the clipping of voltage I missed out on some additional solar production I could've gained.

View attachment 1739177

View attachment 1739179
Click to expand...

Could be a problem of bypass diode on panel failing

Hence it is bypassing a panel causing a voltage drop


Could get a short patch cable and elminate one panel at a time , bypassing it

If the same behaviour happens bypass panel not the one

If behaviour disapears you have the problem panel

You will lose a lot of production
Eliminating a working panel ie one will drop it to 150v if problem panel drops out it will drop below mppt range

Then either warrantee or have bypass diodes replaced or panel replaced

It is gonna take some time to pinpoint , i may be sitting the pot miss just spitballing what i can think of
 
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Based on the voltage i assume panel count is the same in both strings

Are all panels same spec?
Or does string 2 have lower wattage
 
leon.davibe said:
Could be a problem of bypass diode on panel failing

Hence it is bypassing a panel causing a voltage drop


Could get a short patch cable and elminate one panel at a time , bypassing it

If the same behaviour happens bypass panel not the one

If behaviour disapears you have the problem panel

You will lose a lot of production
Eliminating a working panel ie one will drop it to 150v if problem panel drops out it will drop below mppt range

Then either warrantee or have bypass diodes replaced or panel replaced

It is gonna take some time to pinpoint , i may be sitting the pot miss just spitballing what i can think of
Click to expand...
If it's a fault on the solar panels it won't suddenly come back to life by switching of and on.
 
Panels are all the same, one string facing north (PV1) and other West (PV2). I also don't think it is solar panels issues, the voltage is consistence when stuck (you can see it, the voltage is like a ruler straight).

Today the string is working normally and voltage is fluctuating normally as it should be.

Just want to know what is the cause, so it doesn't repeat itself.
 
name_less said:
It seems as if the MPPT for the inverter clipped the voltage, because of the clipping of voltage I missed out on some additional solar production I could've gained.
Click to expand...

Definitely agree with the idea it's the MPPT clipping.

If your power curve was normal, I would say it could just be a measurement/reporting issue. But the power jumps as well when you reset.

So it seems like an MPPT firmware control loop issue. Some chance it's a safety feature such as over-temperature kicking in?

Otherwise it's a straight up bug by the looks of it.
 
TheChamp said:
If it's a fault on the solar panels it won't suddenly come back to life by switching of and on.
Click to expand...
Thinking it gets triggered into bypass maybe early norning by some shade

And then stuck maybe
 
name_less said:
Panels are all the same, one string facing north (PV1) and other West (PV2). I also don't think it is solar panels issues, the voltage is consistence when stuck (you can see it, the voltage is like a ruler straight).

Today the string is working normally and voltage is fluctuating normally as it should be.

Just want to know what is the cause, so it doesn't repeat itself.
Click to expand...
Yea agree the ruler straight is odd
Like the mppt isn't swifting to stay at peak which changes as the temp of panels change the voltage has to change

If the mppt startup voltage is 150v then it may be in straight line on voltage like that ie stuck to the bottom at startup voltage
If some panels are in bypass


Though i think the 8kw deye has 120v startup meaning it can't be the case here
 
Googling the specs the startup is 150v and the range is 125-425

Can only speak of my experience on a cheap device normally the startup is its lowest point

Since i added my panels one by one with surplus cash

I had an array very close to startup (which would mimic a bigger array with panels in bypass due to shade)

Once the peak output voltage drops below startup voltage my inverter stuck at the 120v startup voltage ie straight line as you experienced

Early morning and late afternoon cooler panels meant higher voltage and the voltage would be more squigly hence why i know you can get a straight line on mppt bottom
 
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name_less said:
Panels are all the same, one string facing north (PV1) and other West (PV2). I also don't think it is solar panels issues, the voltage is consistence when stuck (you can see it, the voltage is like a ruler straight).

Today the string is working normally and voltage is fluctuating normally as it should be.

Just want to know what is the cause, so it doesn't repeat itself.
Click to expand...
If the panels are all the same specs you would expect the pv2 array to match the peak 10A of pv1 (not at the same time but at some point in its graph)

ie the voltage will peak normally
As long as half of every panel is in play (ie the two halves of half cut module run in parralel)

So lets say the panel produces 10A peak if half of the panel is in bypass the panel will contribute 5A

Hence if all panels aren't contributing what they should (both halves) the amps will fall short of peak

So the peak Amps on pv2 is a flag for me

Not a solar expert, so may be wrong

I would look back in history too see if pv2 peak amps/kw output ever matched pv1,

Naturaly with no shading in play
 
name_less said:
Panels are all the same, one string facing north (PV1) and other West (PV2). I also don't think it is solar panels issues, the voltage is consistence when stuck (you can see it, the voltage is like a ruler straight).

Today the string is working normally and voltage is fluctuating normally as it should be.

Just want to know what is the cause, so it doesn't repeat itself.
Click to expand...
Swap pv1 and pv2 around and if you see the same behavior on the same side it’s safe to conclude it’s the panels or not.
 
quovadis said:
Swap pv1 and pv2 around and if you see the same behavior on the same side it’s safe to conclude it’s the panels or not.
Click to expand...
Yea this is the easiest solution to troubleshoot

If the problem travels it is panels
If it stays it is inverter/mppt
 
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So this morning it acted up again. I have enabled multiple MPPT point feature now on the inverter. Will monitor and see if it will assist with the problem.

I take it as everyone has mentioned on the forum, that during sunrise the panels are shaded and the mppt controller gets stuck and due to undervoltage. Which means they didn't implemented a brown out reset or watch dog

I take it as bug in the firmware, I have sent and email to Deye about this problem and hopefully they respond and have implemented a fix on the firmware.
 
name_less said:
So this morning it acted up again. I have enabled multiple MPPT point feature now on the inverter. Will monitor and see if it will assist with the problem.

I take it as everyone has mentioned on the forum, that during sunrise the panels are shaded and the mppt controller gets stuck and due to undervoltage. Which means they didn't implemented a brown out reset or watch dog

I take it as bug in the firmware, I have sent and email to Deye about this problem and hopefully they respond and have implemented a fix on the firmware.
Click to expand...
You said the strings are not facing the same direction shouldn't multiple mppt feature have been enabled all along?
 
I meant 'MPPT Mutli-Point Scanning'. I believe it's similar to shadow scan for Goodwe inverters where the MPPT looks for 'global' instead of 'local' MPPT.


aurorasolar.com

MPPT - Everything You Need to Know About Maximum Power Point Tracking

When modeling how much energy a solar design will produce, there are many features of the components that must be taken into account to ensure an accurate estimate. One important factor that modeling software must account for in order to avoid over or under-estimating the system’s energy...
aurorasolar.com aurorasolar.com
 
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Name_less did you ever get to the bottom of this issue? I am seeing the same on my pv 1 on Deye 8kw.
 
if the stuck voltage is close to startup voltage , maybe panel count may be too low
ie lets say you have 4 panels of 40v in series many would think it is perfect for a 120v startup
as the 4x40= 160 way above 120v

while the max power will be produced on a hot day at 30v and when cooler at 33v
so then you will stay stuck on that 120v and produce more power in the morning and afternoon when panels are cooler
and actually get less mid day and have fluctuating voltage morning and afternoon and mid day stuck on startup/bottom voltage of mppt

edit and naturally the same applies to shading
if you have a higher panel count and some are in shading droppoing you down to 4 you will be stuck on startup voltage
 
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