question

vicsla avatar image
vicsla asked

combining MPPT 100/30 & 75/15 same panel and separate batteries and loads

Hi,

I have a 400 watt panel that I would like to use to charge a 24 V battery bank and a 12 V battery bank.

Is it possible for MPPT100/30 and 75/15 share the same panel and charge two separate battery banks?

https://community.victronenergy.com/questions/58105/mppt-7510-and-mppt-10030-in-parallel.html

one sub answer address a similar question;the answer from user 'wild-thing'. Seems like there is a competition,with 12V get fully charged or need to be charged before MPPT 75/15 turns-on.Since in my case the batteries are simultaneously used and hence it may not be practical.

Is there any other way to do this without the controllers competing with each other?

A dc-dc isolated charger may be another option but has efficiency issues ~87% compared to an MPPT charger

MPPT ControllersSolar Panel
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2 Answers
Paul B avatar image
Paul B answered ·

the answer is no, you cant connect two mppt units to the one battery.


HOWEVER

you could connect the 24 volt one up. and then connect the 12 volt mppt PV connection directly to the 24 volt battery and then the battery connect to the12 volt battery

this will then effectively make the 24v battery charge the 12v bank with 15 amps 12v dc until its full. using a orion dc to dc would be better as these have low voltage cut offs and you have more control


down side if you dont get enough solar to recharge the 24v bank you may end up with a flate 24v battery

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vicsla avatar image vicsla commented ·
Hi Paul,

sorry,question is NOT about connecting one solar pannel to same battery bank with two charge controllers .

Single Solar pannel of 24V need to be shared with two separate circuits through two MPPTs,one for 24 volt battery and other for 12 V battery.

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klim8skeptic avatar image klim8skeptic ♦ vicsla commented ·
@vicsla You can not connect 1 solar panel to 2 mmpt's that charge 2 different battery banks.
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vicsla avatar image vicsla klim8skeptic ♦ commented ·
Could you be kind enough to elaborate your answer with some reasons!
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klim8skeptic avatar image klim8skeptic ♦ vicsla commented ·
@vicsla as already mentioned they compete.

Each mppt will be trying to extract the maximum power from a panel at the same time.

Every 10 minutes each mppt will re-scan the panels output, looking for more power.

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vicsla avatar image
vicsla answered ·

Seems not possible to do. Any other solutions other than using a DC-DC converter charger?

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