Solar panels under charging

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sarellandy asked Mar 9, '23

Solar panels under charging

Hi

We have 3x 450/200 Mppts, 6x 540W solar panels connected to to each tracker, 72 panels using all 12 trackers. Today we had a perfectly sunny day, no clouds, 30 deg C, and our total solar generation was 65 percent of what it should be. We often get up to 32-33 KW from the panels on partly cloudy days when the sun emerges from behind the clouds. Here is a graph of what the panels delivered today:

As can be seen on the graph the solar actually drops slowly all the time. Is this maybe caused by something overheating? Max bat temp today was 39deg C. Please let me know if you need any more information or data from me.

Thanks in advance.

MPPT Controllers smart solar charging behaviour

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Answer 1 · 2023-03-09T18:46:24Z

Alexandra answered · Mar 09, 2023 at 06:46 PM

@Sarellandy

It is likely derating. A warm ambient means even warmer unit.

Your batteries are also getting warm. If that is being sensed or is reporting to the mppt that will also affect charge rate.

Panels temperatures also affect performance. (You will see this in the pv voltage graphs usually) So all round its heat.

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Answer 2 · 2023-03-11T06:06:10Z

astrayan answered · Mar 11, 2023 at 06:06 AM

I don't like 39C batteries. I'd be setting the MPPT to 6000 each, until you get on top of that. I presume they are lithium.

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Answer 3 · 2023-03-16T06:36:30Z

sarellandy answered · Mar 16, 2023 at 06:36 AM

Hi all, thanks for the answers, yes the batteries are lithium. We installed a air-conditioned in the room with the solar equipment keeping it at 24 deg C and the charging is very stable now. Making about 20Kwh extra per day. Temp on batteries clearly too high.

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nickdb ♦♦ commented · Mar 16, 2023 at 07:38 AM

At 39C you would be significantly reducing the life of those batteries.

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