MPPT 150/70 solar panels Voltage limit

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Herve RV Nizard asked May 28, '19

MPPT 150/70 solar panels Voltage limit

4 x 270 W Axitec panels - Easysolar 48/3000-MPPT 150/70 - 4 of 200 A (12V) AGM bat in series = 48V - Multi 48/3000 in a easysolar . - BMV 700- Color control . Caribbean area.

Axitec panels are 270 W - 31,12 V 8,71 A

OCV = 38,21 V scA = 9,25 A

Good day,

I had a easysolar 1600/24 with 100/50 MPPT. My panels were in 2 series of 2 for voltage.

I now have a Easysolar 48/3000 with MPPT 150/70. I passed my batteries in 48 V.

For now, I still have 2 pairs of cables arriving from my solar panels . Accordingly there is a little difference between panels voltage and battery voltage .

I like to have far more panels V than Battery. For this one, I am hesitating.

If I put all my 4 panels in 1 serie, I will have :

- Nprmal operation : 4 x 31,12 V = 124,48 V @ 8,71 A . perfectly within MPPT 150/70 limits

- My Open Circuit voltage (max) would be 4 x 38,21 V = 152,84 V ! Slightly above the 150 V limit for the CC. However, I am in the Caribbean with hot temperatures year round ; lowest ever might be 17° C .

Appreciate comments to see if I could take the risk and have only 1 serie of 4 panels .

Thanks

MPPT Controllers EasySolar All-in-One Solar Panel voltage

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Answer 1 · 2019-05-28T18:38:41Z

wkirby answered · May 28, 2019 at 06:38 PM

Do not take the risk.

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Answer 2 · 2019-05-28T18:50:59Z

Kristof G. answered · May 28, 2019 at 06:50 PM

i agree with wkirby,

BUT from what i see here

i have 150/70 mppt and voc of the panels are 128v, but here they never go above 124v... i know there is no extreem weather here... but i dont think they will ever get the max. voc.

but again iam not sure of that... i can only tell ya what i see here...

and i dont know how the mppt will behave when there is a little overshoot...

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wkirby ♦♦ commented · May 28, 2019 at 07:02 PM

The VOC can approach in ful sun and a full battery - no load on the PV array.

Transistor manufacturers usualy state the Vds of their MOSFETs as an absolute maximum rating. Very small margins if any margins are tolerated above this rating.

Stay below the 150V maximum.

As it happns, I am in a very smilar situation to Herve, I would like a 48V system, but I can only go 2S or 4S on my PV, so I'm stuck on 24V with 150V controller.

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Answer 3 · 2019-05-29T12:07:12Z

Herve RV Nizard answered · May 29, 2019 at 12:07 PM

Good day and thanks for your comments.

As a matter of fact you are perfectly right ! Yesterday afternoon, my panels voltage reached 75,3 v ! Good they were not in only 1 serie of 4 or i would have overpassed the 150 v limit.

Fyi was bright sun and heavy load taken from the batteries. So i will leave my 2 series of 2 !!

20190529-080724.jpg (1.7 MiB)

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wkirby ♦♦ commented · May 29, 2019 at 12:15 PM

No problem, happy to help. Happy to help save your equipment! :)

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