question

Mark Anderson avatar image
Mark Anderson asked

6 or 2 mppt contollers

Hi all


just getting started on my full time off grid setup

i have 6x qcell 480w panels and will be getting 2 x 5kw 48v lifepo4 battery packs

I will be living and working from my rig, so redundancy is important

trying to decide on mppt contollers, I have a 40 foot school bus that I’m converting so space is not a big issue

the pales have 11.2a short circuit current and 54v open circuit voltage

i think I could go wit 6x 100/20 or 2x 1 x 150/70

the former is cheaper, so other than having it run more cables through the roof and more ve.can cables, is there a downside to using 6 MPPT contollers?

thanks

mark

MPPT Controllers
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2 Answers
klim8skeptic avatar image
klim8skeptic answered ·

What is the Voc / Vmp of the panel?

I imagine that 1 panel would not have a high enough Vmp to charge a 48v battery.

Likewise 3 panels in series would be over the mppts 150v pv input voltage limit.

Please use the Victron online MPPT calculator..

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kevgermany avatar image kevgermany ♦♦ commented ·
@Mark Anderson

To add, MPPTs require panel input to be higher than actual battery voltage +5V to start charging.

Try 3 parallel strings of two panels into a single 150/70 in the calculator.

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Mark Anderson avatar image
Mark Anderson answered ·

Thanks for responses. Here’s link to panels https://www.q-cells.us/dam/jcr:261eb7ed-4eb2-4049-a64e-44da63fdf056/Q_CELLS_Data_sheet_Q.PEAK_DUO_XL-G10.3-BFG_475-490_2021-08_Rev01_NA%20(1).pdf


Vmpp is only 45v, so I’m figuring 3 strings if 2 and 3 mppts would be best for max flexibility.

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