question

jakudo avatar image
jakudo asked

Better understaning - 2S4P VS 4S2P

Hi,

I'd like to ask you for explanation of voltage and current works in serial-parallel system. I thought that I understand that, however, when calculation MPPT in Victron Excel calculator, it confuses me a bit.

What I thought I know:

(example - panel has 50 V, 10 A)

Serial connection of pannels:

  • voltage multiplies by number of panels - so if panel have 50 V, 2 panels in series have 100 V
  • current stays the same - no matter how many panels I have in series, if all of them have 10 A, the output current is 10 A

Parallel connection of pannels:

  • voltage stays the same - if I have 2 (or more) same panels in parallel conection, the voltage will be always 50 V
  • current - multiples by number of pannels - if I have 2 panels in parallel, I would get 20 A

I've calculated 2 possibile connection - 2S4P and 4S2P in the Victron calculator. The voltage is OK, however, the current si the same in both cases. Why is that? What did I miss?


Thanks a lot for any explanation :)

Jakub

screenshot-2023-01-22-at-190415.png

screenshot-2023-01-22-at-190427.png

MPPT Controllers
screenshot-2023-01-22-at-190415.png (157.6 KiB)
screenshot-2023-01-22-at-190427.png (150.6 KiB)
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1 Answer
klim8skeptic avatar image
klim8skeptic answered ·

The calculator is showing output current to the battery. This will be the same, as the array power output is the same for both 2s x 4p and 4s x 2p.

Your thinking about current input to the mppt, that will be different and not shown in the calcs (but is taken into account).

Your under the mppt's PV input "PV short circuit current" rating of 70a for that controller for either array proposal. All good.

Note, the MC4 connectors are only rated to 30a, take that into consideration.

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jakudo avatar image jakudo commented ·
Oh, I see, thanks a lot for the explanation.
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