MPPT RS Sizing limitatios

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juusperunma asked Oct 3, '22

MPPT RS Sizing limitatios

Hello ,

Im planning a setup with panels of these specs:
460 Wp
Max Isc : 14.01A
Max Voc: 41.48V

These will be connected to 48v LFP battery and MultiplusII, 3 phase.
The panels will be in an area where temperature can get to -20C in winter for few days.

The Mppt RS 450/100 seems to be the suitable for the project.
However, the specs seem overwhelming and I'm not sure how to size it correctly.

Question is: What are the limiting factors with these panels?
What is the Maximum number of panels of these specs and in what kind of configuration for ONE RS unit?

RS Pv short circuit max is 20A, and voltage cannot exceed 8x battery voltage does this mean I can only install these kind of panels in series per tracker? So a maximum of 20 panels , from my initial beginner understanding?

Also Manual for Multiplus Inverter says only 38-66 Volts max DC income, but not max Current specified in data? Does the incoming current from MPPT not matter for the inverter?

thanks.

charger Solar Panel solar sizing

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Answer 1 · 2022-10-03T21:54:16Z

Guy Stewart (Victron Community Manager) answered · Oct 03, 2022 at 09:54 PM

With so many possible variables on panel types, sizes and wiring configurations we created a calculator that allows you to input the panel specs and configuration to see if it would be within the MPPT limitations.

Have a go here - https://mppt.victronenergy.com/

The maximum current produced by the MPPT will not be a factor for the inverter, but it might be for the batteries (and their wiring and fuses).

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Answer 2 · 2022-10-04T23:20:39Z

juusperunma answered · Oct 04, 2022 at 11:20 PM

Ok, thank you for the clarification.

So the limiting number of panels seem to be 7 in series / tracker if temp dips to -21C.

Is it possible to install a SmartSolar MPPT 150/85 along side a RS unit, or do additional mppts have to be exactly the same kind?

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Guy Stewart (Victron Community Manager) ♦♦ commented · Oct 04, 2022 at 11:24 PM

Any combination of MPPTs is allowed, as long as their individual specs are conformed with.

There are several features (either DVCC, VE.Smart Network, or VE.Can) that allow for syncing of different Victron MPPT charging states/parameters - so it would also be a good idea to research their limitations first if you decide to go that way.

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Answer 3 · 2022-10-05T06:43:36Z

scraggs answered · Oct 05, 2022 at 06:43 AM

You might want to check that the voltages from the RS are suitable for your needs, they are restricted to a maximum voltage of 62v and the issue we had was the current rate on equalisation is low if you have a big battery pack.
We have had to change our plans because of these restrictions, which is a shame as the unit ticked all the boxes for us otherwise.

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Answer 4 · 2022-10-05T14:34:33Z

juusperunma answered · Oct 05, 2022 at 02:34 PM

What kind of batteries you had ? As far as I'm aware, LFP batteries do not need equalisation settings, so shouldn't be an issue for us.

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