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kaypea avatar image
kaypea asked

MPPT charge reduces to zero for no reason

I have recently fitted a new EasySolar II GX and have a problem that I don't seem to be able to resolve. The unit is fitted with an MPPT250/70 solar charger which no reason that I can see, just stops charging on a nice sunny day - see attached graph from today.smartsolar-charge-dropout.jpg

As can be seen, a nice sunny day and suddenly the current drops off to zero and will sit there until I turn the MPPT off and then back on again.

System is 24v, charge current set at 50amp max (calcium lead batts), load output set to always on. 6 x solar panels 1800w max.

As can be seen the solar voltage rises slightly when the charger goes off, and when reset comes back on. This happens most days, but there is no tie-up between when it goes off each day. Its a new system thats only three weeks old, and has done this from new - I'm begining to think its actually faulty or is there some setting I'm missing?

MPPT Controllers
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13 Answers
marekp avatar image
marekp answered ·

@kaypea

Is it possible that the PV voltage is too low to charge the battery?

MPPT voltage needs to be 5V higher that the battery voltage for charging to take place.

When battery started charging its voltage was less than 25.6V and PV voltage was more than 31.6V.

When the battery voltage reached 25.6V and PV voltage stayed at 31.6V there was no 5V difference between battery voltage and PV voltage and charging stopped.

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kaypea avatar image kaypea commented ·
Hi - Its 5v to start charging, and then more than 1v difference to keep charging. The Batteries are at 25.6v and the panels are giving more than 36v, but the charger current stays at zero. If I limit the solar charge current to 22amps, then all stays well - more than 22amps and it trips out. My panels are 8months old and total max should be 1800w at 32v (56amp max in theory).

(31.6v minus 25.6v = 6v difference so it should be on charge at those voltages).

Thanks for your comment.


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marekp avatar image marekp kaypea commented ·
@kaypea

Ok, but if PV voltage drops for a moment below 1V over the battery you will need 5V difference to start charging again.

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kaypea avatar image kaypea marekp commented ·
That day (as in the above graph) was a sunny cloudless day and there were no dips. You can see on the graph that the voltage from the panels actually went up to over 36v when the charging load went to zero. I've also got a Chessell chart recorder connected which shows the voltage always stayed well above 30v. I agree 100% with what you are saying about the charge threshold voltage differences.
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marekp avatar image marekp kaypea commented ·

@kaypea

You could be right, but MPPT from time to time is looking for the max power point (hence the name MPPT) and during that search the PV voltage can drop.

I am not saying that this is a cause of you problem, but clouds are not needed for PV voltage to drop for moment.

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klim8skeptic avatar image klim8skeptic ♦ kaypea commented ·
@kaypea looks like the transition from absorption to float to me.

There is a widget that shows the mppt's charging state.

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kaypea avatar image kaypea marekp commented ·
I think you ultimately hit the answer... I rewired the solar panels (6) into three groups of two series panels to keep the voltage much higher than the battery voltage. The input to the MPPT is now in the region of 60v and there has been no drop outs over the last two days, so it would seem the marginal difference between panels and battery did drop to less than 1v. Why it did not restart when the batteries were 25v and the panels were 36v, I'm not sure about, so that may remain a mystery. Thanks for your help.
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rolfniem avatar image rolfniem kaypea commented ·
Hi, I have the exact same problem however it is 52V battery and PV voltage is 92V so way above the 5V and nothing. Chares all okay and then randomly decides to stop. And no way to reset. Powered down and restarted and still nothing.
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kevgermany avatar image
kevgermany answered ·

What state is the solar controller in during the cut out? (Screen shot of the charger from Victron connect would be great)

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kaypea avatar image
kaypea answered ·

I'll get a screen shot next sunny day I have - Everything on the MPPT bluetooth looks okay as far as I can see - load shows 'on', but the solar charge current has fallen to 0amps, battery voltage is around 26volts, and solar shows around 35volts since no current is being drawn.

I'll screen shot it next time it happens.

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seb71 avatar image
seb71 answered ·

Does the MPPT have the latest firmware?

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marekp avatar image
marekp answered ·

@kaypea

What is the SOC at the moment of current drop off?

Anything similar to this?

https://community.victronenergy.com/questions/175803/mppts-switch-off-when-soc-is-getting-colose-to-100.html

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kaypea avatar image
kaypea answered ·

More info from this sunny morning as its dropping out at the moment...

  • Yes I have the latest software (so it tells me)
  • State of charge - unknown, but battery voltage 25.6v when it trips the solar charger whilst charging this morning so not fully charged - shows Bulk (hasn't yet goto absorpsion)

This morning, by keeping the solar charge current max set at 22amps, it stays on. Goto a higher charging value, the Smart Solar charging output shuts down, then tries to recover, but keeps tripping once it exceeds around 700w on the 'meter'.

I tried to catch the app from my phone whilst it was down.. (just starting to recover)

EDIT: After limiting the charge current to 22amp, its stayed on since - The battery charge status has managed to go through absorption and is now steady on float. So it seems to be linked with a power of over 700w it trips the output to zero charge current. The sun has stayed out all day so far. Maybe the MPPT is overheating or has a software issue? Looking at this forum, I am not alone with this problem.

jpeg-scan2023-1-310002.jpeg



jpeg-scan2023-1-310002.jpeg (360.1 KiB)
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kaypea avatar image
kaypea answered ·

Can anybody give me any more direction that may help? Is it possible the new MPPT is faulty? Any Victron representative on here that can offer any advice?

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kaypea avatar image
kaypea answered ·

I'm still having this problem of dropouts from the MPPT control/charger. I've included two new shots from a few moments ago which shows plenty of PV voltage, but the charger remains completely off - not even supplying power to the inverter You can see from the graph it only restarts after resetting the solar MPPT. Its a bright sunny day again with no clouds in the sky, sun is directly south at the moment (directly facing the panels), the MPPT is stone cold to the touch so don't suspect over-heating is an issue. My old cheap MMPT solar controller never had this issue!

jpeg-scan2023-2-130001.jpeg

still-drops.jpg


still-drops.jpg (192.8 KiB)
jpeg-scan2023-2-130001.jpeg (385.2 KiB)
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markobaldo avatar image
markobaldo answered ·

I’m having the same issue; bright, sunny day. Yes, latest firmware.
SOC = 92.1%
Battery volts = 52.04v (48v nominal battery bank)
State = ”Bulk”
Watts = 3w
What gives?

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rolfniem avatar image
rolfniem answered ·

I have the exact same problem. Did anyone resolve this issue?

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klim8skeptic avatar image klim8skeptic ♦ commented ·
@RolfNiem you might want to open a new thread and actually post some details of your problem.
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raymiller avatar image
raymiller answered ·

IMG_5068.PNG

Me too. I have the same issue with SmartSolar MPPT Charger 100/20 intermittently stopping to zero output, but it does recover eventually. I have 300W of PV on a 24V system VOC 36V. The problem can be reset manually by open-circuiting the PV circuit breaker and reconnecting it, the MPPT returning to normal operation in seconds. The MPPT seems to need a zero voltage input to be able to reset the MPPT algorithm, Voc condition and no output power seem to be ignored. This is how I know it is an MPPT problem. I have also experienced this same issue with other MPPT 75/15 as well.

The problem ONLY occurs with a fast loss of solar irradiation on a part cloudy day, this seems to be the root of the problem with the MPPT hardware/firmware not being able to track the very large power transients. It would be very nice to finally get this problem out of the system which has existed for many years.


img-5068.png (520.5 KiB)
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raymiller avatar image raymiller commented ·
Also latest firmware...
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stephen-plank avatar image
stephen-plank answered ·

Did this ever get addressed?

I am having same issue. Our victron controllers (x2) have stopped, now resorting to diesel engine to charge batteries.

Very disappointing for a unit that is barely a year old.

https://community.victronenergy.com/questions/234420/mppt-10050-bulk-charge-no-amps.html


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Lucian Fratila avatar image
Lucian Fratila answered ·

I have a same problem, for me all good during the day, but next day in the morning it's not pushing current into battery, I can see that on my Shunt, only after few resets I can make it work

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