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voltmeister avatar image
voltmeister asked

Does Victron have a Dual input mppt?

I want a mppt capable of at least 2 separate strings with different voltage, combining and converting the two to battery. Fully utilizing both strings?

If the answer is you need 2 different mppts, one per string, then how can I merge the two mppt’s to provide stable output to battery?

Also can the victron mppts limit current to the battery. If yes, can I in the settings choose for the excess power to be added to the voltage? (Higher voltage).


I plan to feed power stations that can handle different voltages. (But not two different voltages)

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seb71 avatar image
seb71 answered ·

If the answer is you need 2 different mppts, one per string, then how can I merge the two mppt’s to provide stable output to battery?

For small systems, use VE.Smart Networking.

For larger systems, add a GX device.

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There is also the RS MPPT option (for large systems).

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voltmeister avatar image voltmeister commented ·
Thanks. Seems VE.Smart Networking can solve it.

I still need answer to; if I limit the current to e.g. 12amps on each mppt, can I have the excess power convert to increased voltage instead? Let's say I set the mppt to 24v and limit the current to 12amps, what happens to the excess amps the PV produce/injects? Is there a setting where I can utilize excess power when setting an amp limit on the mppt bellow PV.

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wkirby avatar image wkirby ♦♦ voltmeister commented ·
The PV does not "inject" power into the MPPT. The MPPT takes as much power as it needs from the PV array.

If the array is capable of providing more energy than the MPPT is taking, then that wasted is wasted.
If you want to maximise the capacity if the array, then you have to use it. Do this by applying a useful load on to the system. For example, if the MPPT can make 10A from the solar panels and the battery can only accept 5A because it is close to full, then you need to apply a load on the system of 5A to maximise the capacity of the array. There isn't a setting to apply a virtual load on the system, the load needs to be real.

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snoobler avatar image snoobler voltmeister commented ·
Limit MPPT to 12A, you will only get 12A output.


@Seb71 mentioned it, but to elaborate, if you want to have your maximum solar available for loads, but restrict charging, you:


  1. Get a GX device
  2. connect all MPPT/chargers to GX device
  3. enable DVCC
  4. Set maximum charge current in DVCC


This will limit CHARGING to that specified in 4, but it will draw whatever it can from the array to power loads.

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voltmeister avatar image voltmeister snoobler commented ·
Thanks! so if the mppt draw more than what it can charge (due to charge current limit set in mppt), the only way to make use of the excess the array can give is to have a proportionate load as wkirby describes? is that the case with DVCC also?


The mppt's supporting 12/24/36/48v , instead of charging 12 or 24v I choose to charge with 48v. I assume the charge current from the mppt will be lower on 48v compared to 12v ? if the charge voltage is flexible, but current is limited you could decrease current from the same array by increasing voltage?

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snoobler avatar image snoobler voltmeister commented ·

@WKirby is talking about something different.


I'm telling you that if you set your current limit in the MPPT, that's the limit. If your array can provide 20A of charging, but you limit it to 12A, it will NEVER put out more than 12A.


DVCC manages all connected chargers, e.g., if your two MPPT can put out 20A each (40A total), but you set the DVCC charge limit to 24A, it will NEVER send more than 24A to the battery, but it will allow the full 40A for loads if needed.

I use DVCC to limit my charging to 15A @ 48V, but my array can output up to 55A or so if I need it for loads.

Charge current is the current. Same current for 12, 24 & 48V. 100/50 means, 100Voc max PV input and 50A max output - regardless of battery voltage.

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voltmeister avatar image voltmeister snoobler commented ·

Yes, but if you set the charge current limit (to battery) to e. g. 10 amps. The total watts going to the battery will differ significantly weather you choose to charge12v vs 48v.

120watts vs 480 watts.

Correct?


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seb71 avatar image seb71 voltmeister commented ·

The nominal battery voltage (12V/24V/48V) is not something you change for a certain system.


So you select the appropriate charger (and PV array), based on the output current you need/want, knowing the nominal battery voltage you will use.

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voltmeister avatar image voltmeister seb71 commented ·
The power station can take from 12 to 150v. Doesn’t matter what voltage I provide, but it can only take 12 amps.

Another station can take 12 to 50v up to 20amps.

With 2 different PV strings from different manufacturers and voltages, I want to be able to combine the two strings and stay within the amp limits while fully utilizing both pvs. I’ll have to figure out how to switch between the two PS’s in step two.

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seb71 avatar image seb71 voltmeister commented ·
You want to use the MPPTs without a battery? Connected to those power stations instead of a battery?
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voltmeister avatar image voltmeister seb71 commented ·
Yes but there is a battery behind the PS. the input can take up to 150v and up to 12amps.
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