question

Mike avatar image
Mike asked

Stacking 4 Victron SmartSolar 100/20 MPPTs

Hello, my apologies for being very new here and fairly new to solar charging. Forgive me for a simple question, but I want to confirm my assumptions:

My son's high school Solar Car club intends to stack 4 SmartSolar 100/20 MPPTs and I wanted to confirm that all they have to do is attach all 4 of the MPPT battery charge outputs to the busbar attached to their 48V 100Ah LiFePO4 battery.

Each MPPT will have 3 panels in series. They are using some old Renogy 100W panels. VOC=22.5V. Short Circuit Current 5.75A.

Any things they need to watch out for?

Synchronization via Blutooth needed?

Thanks for the advice in advance.

MPPT ControllersMPPT SmartSolar
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2 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

Make sure the COLD open circuit voltage of the three panels in series doesn't exceed 100 volts. Voltage goes up as temperature goes down.

Insure the maximum charging current of your battery is not exceeded.


Otherwise it should work fine.

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kevgermany avatar image
kevgermany answered ·

They don't need 4 MPPTs for this.

Two strings of three panels into each of 2 MPPTs would be just as good.

Don't forget fuses.

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Mike avatar image Mike commented ·

The kids are thinking that 4 MPPTs is going to be more efficient. I will talk to them about it. There are definitely Fuses and Breakers everywhere. This car has to pass the competition's safety reviews/checks before they can race. But still need to be very careful.

Thanks for the answers and advice!

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duivert avatar image duivert Mike commented ·
4 mppt’s is only usefull and more efficient if the panels are facing in different directions
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Mike avatar image Mike duivert commented ·
Aha... that makes sense. Great info here. Thanks!
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