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bigbloke avatar image

dimension question - 75/15 versus 100/20 - max PV input ?

Hi All,


* Charging 12 volt 220AH (2 x 110AH battery bank)
* 2 panels both 24V short circuit - already purchased
* Planning to install in series , looking to select a controller

75/15 or 100/20 ?


Well...

My PV voltage is well under 75 at 48V peak
My PV current will be about 6A

So on paper the 75/15 firs the bill

BUT - my total "theoretical" panel power in Watts will exceed the "nominal" figures quoted here:

https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-75-10,-75-15,-100-15,-100-20,-100-20_48V-EN.pdf

by a good few watts

given I and V are well under, is that alone enough to say "the 75/15 will be enough"?

or should I err on the side of caution and get the bigger one please (and why please)

Many thanks in advance

Regards

BB




MPPT - Solar Charge Controllersmart solar set-up help
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2 Answers
Matthias Lange - DE avatar image

Do you have a datasheet or a model number of the panels for us?
The important specs are the open circuit voltage Voc + temperature compensation (%/°C) and the lowest temperature at your place.

You can enter all specs into this calculator:
https://www.victronenergy.com/mppt-calculator

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N-DEE avatar image

If you're using them in surroundings with higher temperature i would take the 100/20
They "only" have 100% up to 40 degree. 75/15 may go well beyond 40 degree resulting in e.g. 80% of 440w (-> 352w) @24v

br,
Andy

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