24V or 48V system for an island using 2 ModelS-Modules, with the future option for PV

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batteryb asked Apr 19, '20

24V or 48V system for an island using 2 ModelS-Modules, with the future option for PV

Hello.

I am wondering if I can go for a 48V setup and MultiPlus (C/II) with my 2 ModelS modules.

Initially I will only have an island, which will either be charged by shore power, or a Generator.

I however want the option to add PV in the future, and might initially be limited on the available space for PV modules (probably 1-3 only).

So the question is:
How many PV modules would I need to feed a 48V system trough a MPPT charger?

The question is not, if the PV will have enough power to keep the batteries charged, the question is, if the PV will have enough Voltage to feed (whatever amount of energy from the sun) trough a MPPT charger to my batteries in a 48V setup.

Thank you for reading.

voltage

2 |3000

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Answer 1 · 2020-04-20T12:08:29Z

JohnC answered · Apr 20, 2020 at 12:08 PM

Hi @BatteryB

With typical panels, you'll need to series string at least 2x. And I'm talking 'typical', not some low-V '12V' panels, or monster high-V ones either.

And then consider the available (Victron) mppts that can do low-A 48V. The smallest is 100/20-48, and for longer strings (maybe 3x) the 150/35.

Run the panel specs through this calculator: https://mppt.victronenergy.com/

Also take a good hard look at your batt modules. Some of these bargains can be too off-spec for the mppts to be able to handle weird charge V's. And they won't normally substitute for a good BMS anyway.

Take care..

2 |3000

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