Can I safely add a third mppt?

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justin-adan asked Jan 2, '24

Can I safely add a third mppt?

Hi all,

I currently am running a quattro 48/8000, with 2 current MPPT's linked to 2 different facing strings. These charge 7 Pylontech US3000C's. During summer the incoming PV from the panels caps out around 6500w from the MPPT's. I am however interested in understanding if I can add a third controller of say another 2500w - 3000w, to get my batteries charged faster in Summer, and secondly during winter to get me more PV time. The sun shifts quite a lot in winter so I'm wanting to angle this third string most optimally for Winter collection.

Any ideas where I can start research or find any additional info around MPPT and charge limits? Also not clear to me is if the quattro will be limiting factor here at all?

MPPT Controllers mppt calculator

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Answer 1 · 2024-01-02T13:11:54Z

kevgermany answered · Jan 02 at 01:11 PM

Quattro isn going to affect it unless you charge from the grid.

You don't say if there's a GX device in the system. Correctly set up, this will allow the Pylontechs to control charging across the MPPTs and quattro.

Otherwise a third MPPT can be installed, as long as you respect the charging current limits of the batteries.

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Alexandra ♦ commented · Jan 02 at 01:24 PM

This.

The limit is the max charge amps to the battery. 7x37A is 259A max in bulk charge - information that can be found on the pylon batteries.

If there is a GX is (meaning the system charge amps) will all be taken care of and throttled by the batteries when necessary. Even if you also charge from the Quattro at the same time. (Which depending on your model is 100A or 140A max) it will be controlled.

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justin-adan commented · Jan 02 at 01:59 PM

awesome thanks guys, so I was then correct in understanding the MPPT's can charge the batts direct, as can the quattro from grid. And I only need to consider overall charge limits. But the cerbo will keep everything nicely under control.

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