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ponzoa asked

MPPT RS 450/200 issue. need help

I have a cliente with a MPPT RS450/200 and also a 150/85. The 150/85 works fine but the RS 450/200 is fluctuating between 0 and 30 or 50W pero string. The fluctuations last 1 second and back to zero.

Voltage on the strings is fine at some 342, 283, 338V (only 3 of the 4 strings connected).

The current doesn't seem to be able to get above 0.5A

It is correctly detecting the battery voltage.

It is not registering an errors.

Is on latest firmware. Is slave. resistance is some 76MOhms. External Control (controlled by BMS - Pylontech US3000C via Cerbo GX)

Any suggestions on what this may be and how to solve it?

MPPT Controllers
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Alexandra avatar image Alexandra ♦ commented ·

@ponzoa


And polarity is ok?

Mppts updated and programmed correctly?

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ponzoa avatar image ponzoa Alexandra ♦ commented ·
Yes, it was working great before, nothing touched.
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nesswill avatar image nesswill commented ·

I see this behaviour when i don't have quite enough light to get to the required level on my RS 450/100 (the angle of the panels also can have this effect) until the voltage stabilises then fine.

Might not be the same as you have just a thought.

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ponzoa avatar image ponzoa nesswill commented ·
They sit at about 15º south and west. The panels on the 150/85 are the same with the same angle albeit facing west and they're doing fine, even in the morning.


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nesswill avatar image nesswill ponzoa commented ·
I guess the 150/85 will start sooner because of the lower voltage required but this is only a guess.


When you have sun on are they ok? Mine are.


This could be a fault or expected behaviour i am not sure sorry.
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ponzoa avatar image ponzoa nesswill commented ·
Unfortunately not. It's been like this for a month now. Installed in summer and working fine, I thought it was just the cloudy weather we've been having. Now sunshine is back, It's unable to get above 180W max between the three strings.
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nesswill avatar image nesswill ponzoa commented ·
Ok

So not the same as me. As suggested i would check all the wiring incase something has come loose, if not it might be faulty.

Sorry I can't help.

Good luck and please let us know how it gets resolved.

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ponzoa avatar image ponzoa nesswill commented ·
Yeah, just witing for the client to give me the OK to go visit. Will check that and do a full hard reset too and check the comms just in case.
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ponzoa avatar image ponzoa ponzoa commented ·
I received the OK to visit tomorrow morning. We'll see what I find. Any suggestions for test or what to check are welcome.
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1 Answer
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ponzoa answered ·

At the end it was a faulty Victron Battery Switch 275A. This was making a bad contact but enough for the solar charger to read the battery voltage but insufficient for it to let any current pass through. Remove the switch and connect the cables having it direct to the Lynx Distributors and it's working fine now.

Thanks for those who contributed.

Have a Merry Christmas!

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nesswill avatar image nesswill commented ·
Useful information thanks for sharing.

Glad you found the issue.

Merry Christmas.

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