question

tpwchr avatar image
tpwchr asked

MPPT calculator problem

Hi. I think something might have changed in the MPPT calculator from victron. I am writing down the values of the solar panel i'm interested in, and its getting no results even for just 1 solar panel. Or maybe I'm doing something wrong, but I remember writing down same values before and it would show me different MPPT's.


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MPPT Controllers
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3 Answers
JohnC avatar image
JohnC answered ·

Hi @tpwchr

With 48V system voltage selected there is no suitable mppt. Try again with realistic data..

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tpwchr avatar image
tpwchr answered ·

My bad!! I wasn't selecting the total number of solar panels in series or parallel, therefore it was not showing me any result. But as soon as I put 3 parallel 4 series it works.

@JohnC your answer has confused me a bit. Isn't this a 48V system?

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JohnC avatar image JohnC ♦ commented ·

@tpwchr

It's whatever you want it to be..

If you want 48V, then you'll need between 2 and 4 of those panels in each string. More than 4 and it will be too much for a 250/ unit.

If you only wanted 12V then it would accept 1 panel/string.

12x of those panels would cough a 250/100, and be a great match at charge voltage.

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tpwchr avatar image tpwchr JohnC ♦ commented ·

Thanks a lot. Definitely I need 250/100 for 12 solar panels. regards!

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Warwick Bruce Chapman avatar image
Warwick Bruce Chapman answered ·

The MPPT requires PV voltage to be at least 5V above battery voltage to work. The voltage from just one panel would be insufficient to start the controller.


From the MPPT datasheet:

"1b) The PV voltage must exceed Vbat + 5V for the controller to start.

Thereafter the minimum PV voltage is Vbat + 1V"

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