question

joeccv avatar image
joeccv asked

Changing 12v to 24v system on MPPT sizing tool - No change to controller?

Here's the configuration


When changing the system voltage from 12v to 24v on the MPPT calculator, I would expect a different charge controller to pop up. However, the controller stays the same.

I am using 4-6 lithium batteries, 100ah 12v each. Four 330w panels, 2s2p, all specs listed in link above.

My expectation if I design based on the MPPT spec sheets is that I could use a 100/50, or 150/45 if the battery bank is wired at 24v. However, the tool continues to point me to the 150/85, which would seem appropriate for a 12v battery bank.

Am I just missing something?

I also am trying to use the excel sheet but only see directions in french. Where are the directions for the excel sheet?

MPPT ControllersMPPT SmartSolarmppt charging
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2 Answers
seb71 avatar image
seb71 answered ·

Try this:

- click on your link

- change the battery voltage from 12V to 24V

(up to this point same chargers are suggested)

- decrease the parallel strings from 2 to 1

(now you will be suggested 100/20)

- increase the parallel strings from 1 back to 2

(now you will get the expected result: 150/45)


Probably it would get you this expected result if you manually fill in all the data, starting with 24V for battery voltage.


So it's some bug with the calculator.

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wkirby avatar image
wkirby answered ·

It is indeed behaving strangely, not refreshing upon battery Voltage change.
One way around it is to select the battery Voltage then select the "Victron module" radio button at the top and then right away select the "Custom module" radio button. Your custom parameters remain filled in, but the selection of MPPT's changes.

I don't think there is an English version of that guide yet.

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