MPPT reset-looping during good sun for minutes on end

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cross-entropy asked Apr 28, '23

MPPT reset-looping during good sun for minutes on end

Dear Community,

i am trying to narrow down an issue with my ESS, using an EasySolar II GX 48/5000/70-50 (wth the MPPT 250/100 inside) on L1, and a new PV array. I have seen a similar issue reported here but OP never came back with a response: https://community.victronenergy.com/questions/77928/smart-solar-mppt-25085-cycling-pv-to-0-after-154-u.html?sort=votes

Some context:
The specifications of the PV are well within the maximum capacity of the solar charger and there are no errors reported anywhere, but during high sun intensity, the MPPT keeps cycling from off -> wakeup -> external control, sometimes staying in off for tens of minutes.

Grid feed-in is set to 4400W, there are no charge or other limits set anywhere, except a 25A grid limit.

This behavior reproduces every day when the sun is hitting the panels at good intensity, the example below is from yesterday (cloudy).

It looks like this in the vrm:

the corresponding console daily history shows we were below 100A and didn't exceed the maximum nominal PV Power:

The batteries were in the low 10s%:

In some cases later, this issue is followed by an overload warning on L1, but i assume this may be due to a spike in feed-in or battery use, to compensate the loss 3-4kW of solar. Here is the full picture (hopefully readable). Not all such instances are followed by overload warnings - can it be the case that VRM does not show these?

We are planning to setup another array like that in a month and any help narrowing down this issue would be appreciated! I have the second MPPT 250/100 already and am planning to test with that one later as well.

Thank you in advance

MPPT Controllers ESS Pylontech

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Answer 1 · 2023-04-28T05:40:57Z

ejrossouw answered · Apr 28, 2023 at 05:40 AM

Is the system configured to manage each phase separately or as 'net metering'? A likely cause of the overload is the PV max which was 4764 which is higher than the 4400W output of the system is rated for. There are some posts out there discussing the DC export mechanism limitations and what you can expect with 'oversizing' arrays or occasional spikes in your case. (in simple terms, the export limit setting does not take into account exiting loads meaning if you e.g. have loads of 500W, the 4400W will be on top of that) Not really a big issue for you. What are the ambient/MPPT temperatures?

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cross-entropy commented · Apr 28, 2023 at 08:28 AM

Aha, i will look into DC export then, thanks. The system is set to net-metering and is trying to compensate loads as well as feed-in the difference on the other two phases - other two Multis will arrive soon to fix this issue, but my assumption was the diff will just go into the batteries.

The temperature 15.37C in the room, batteries are showing between 13-17C.

Took a picture with the thermal imager and inverter components are around 37C. Fan is off.

The PV max was at 4764W but these were at ~176V - so this should be lower when converted to 230V AC, i think?

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Answer 2 · 2023-05-07T10:58:09Z

cross-entropy answered · May 07, 2023 at 10:58 AM

Ok so i found the culprit and it appears whether there is load or not, around when the PV hits its maximum current.

Monitoring MQTT Topic `N/c0619ab206fa/solarcharger/273/DeviceOffReason`

i saw it flip when the charger shuts down during load (see below)

now if someone could shed a light on what reason 8 is and how to override it to not switch off, we could work around the issue.

The VE.Direct Protocol defines Off reasons here, with 8 being "Remote Input" - It is not clear who the remote is in that case - the only external control set is the Grid Setpoint

ref: https://www.victronenergy.com/upload/documents/VE.Direct-Protocol-3.32.pdf

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Answer 3 · 2023-05-17T09:31:10Z

cross-entropy answered · May 17, 2023 at 09:31 AM

Update: This issue still happens with warmer batteries, reproduces as soon as the Charging hits ~70A. I added another Pylontech US3000C, so we have now 6 in total, but the problem persists.

OK after almost a month of pointless isolation activity, i know what happens, and have a hypo why - i will heat the storage shed to 30 Celsius and see if it reproduces. If the current is severly limited by temperature, it would be wonderful to have a note in the specifications, an alert and a VRM chart to correlate:

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