Two MPPT, one generating little charging

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ningaloo asked Jun 3, '23

Two MPPT, one generating little charging

I have two pairs of solar panels each with own smart solar MPPT.

First pair are 2x 120W panels with 100/20 controller generated over 1Kw yesterday. Happy with this.

Second pair are 2x 80w panels with 75/15 controller only generated 30w. Something is wrong. When first installed these could generate 700w in a day. The panel voltage/current seems ok but it's just not getting pushed into my batteries.

Images show history from yesterday when I was not using shore power and current status of the suspect set of panels. I read this as 29W network but only 3W charging. Is that correct?

Any thoughts on what could be going wrong?

MPPT Controllers Solar Panel

screenshot-2023-06-03-08-39-07-658-comvictronenerg.jpg (372.3 KiB)

screenshot-2023-06-03-08-39-37-602-comvictronenerg.jpg (356.4 KiB)

screenshot-2023-06-03-08-45-14-016-comvictronenerg.jpg (284.0 KiB)

2 |3000

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Modifications Space

Node Red Space

Answer 1 · 2023-06-03T05:54:57Z

kevgermany answered · Jun 03, 2023 at 05:54 AM

Your smaller array is not reaching a high enough voltage to start the MPPT. It must reach battery voltage plus 5V to turn on and maintain battery voltage plus 1V while charging.

Check cabling, connections, switches/isolators etc. Could also be dirty panels or faulty panels.

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ningaloo commented · Jun 03, 2023 at 06:53 AM

Thank you. I can see that the PV voltage is below battery + 5V in the image but it does vary and has reached 20V. I assumed that the threshold had been reached as the state shows Bulk rather than Off.

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pwfarnell ningaloo commented · Jun 03, 2023 at 07:52 AM

True, it has turned on but it still has all the symptoms of a high resistance so check connectors, switches, fuses etc. Do you have either of the switches shown below in the system because these are well known for poor contact.

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inline-breaker-12v-24v-48v-20a-to-150amps.jpg (60.2 KiB)

waterproof-manual-reset-dc-circuit-breaker-inline.jpg (44.0 KiB)

ningaloo pwfarnell commented · Jun 03, 2023 at 08:52 AM

Thanks. This gives me something to check. The solar wiring is not the best and is on my to-do list to revise. However today's challenge is some awkward to access plumbing!

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Answer 2 · 2023-06-03T09:01:24Z

paul-campbell answered · Jun 03, 2023 at 09:01 AM

I assume they both have the same target charge voltage/current settings?

Do they both see the same battery voltage?

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ningaloo commented · Jun 03, 2023 at 11:32 AM

Yes, both see same battery voltage and are connected with my smartshunt smart network.

I have changed the smaller panels from parallel to series to boost the voltage but still only generates 1w although voltage is now up to 30v.

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