question

sorin-t avatar image
sorin-t asked

Charge controller advice

Hello,

What charge controller do you recommend for 2 solar panels 300W / 24V.

Thank you!

MPPT Controllersbattery chargingSolar Paneldesign
2 comments
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wkirby avatar image wkirby ♦♦ commented ·

What is the Voltage of your battery bank? That is quite an important factor.
Are the solar panels 300W each for a total of 600W?

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sorin-t avatar image sorin-t wkirby ♦♦ commented ·

Thank you :)

The voltage of the battery bank is 24V (I want to use 2 batteries like: 12V/100AH like this: https://www.dbsolar.ro/baterii-gel/baterii-gel-fotovoltaice-acumulatori-panouri-fotovoltaice-ieftin , put on series).

And the total power for the panels is 600W.

What I want to use it is for some lights and to charge a laptop/phone (using a 24V->220V inverter).


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2 Answers
wkirby avatar image
wkirby answered ·

Great, thanks for additional information.
The higher the battery Voltage, the less current you need for the same amount of power.
So with 24V battery Voltage, you'll need a charger capable of delivering: 600W / 24V = 25A.
Next thing is the maximun PV Voltage. Usually 24V panels have an open circuit Voltage (Voc) of around 38V. If possible, you'd wire these two panels in series to achieve an array Voc of 76V. This Voc could be higher in cold sunny weather, so the 75V range of MPPT chargers would be damaged.
So, you are now into the 100V range of chargers. We calculated earlier on that you'll need at least 25A of battery current, so it works out that the 100/30 would suit you well.

Do try and think a little bit ahead, if you have even the slightest idea that you might expand your PV, then perhaps you could stretch your budget to a higher current controller to allow simple expansion in the future.

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sorin-t avatar image sorin-t commented ·

Thank you!

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Alexandra avatar image
Alexandra answered ·

@Sorin T.

https://www.victronenergy.com/mppt-calculator

WKirby is right. Battery bank voltage is important as well. If you follow the link provided and fill out your panel and system details, you can find out what charge controllers are recommend with the way you want to connect them (parallel or series).

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sorin-t avatar image sorin-t commented ·

Thank you!

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