question

chrisgru avatar image
chrisgru asked

Shared PV negative with two Victron MPPT chargers

hi there,


I have two 150/85 victron charge controllers that I want to use to charge a single battery bank.

I have two solar arrays, each is sized for one charge controller.

I know the pv positive cables from each array need to be kept separate for each charge controller. Can the pv negative from my two arrays be on a combined cable?

I would run a larger negative cable if the negative cables can be combined.


I plan to use a midnite solar mnpv12 combiner box, and combining the negative feed for both arrays is the configuration shown in the manual with two charge controllers. The positive feeds are kept separate of course. I would have to cut the negative bus bar in the combiner in half to separate it per charge controller.

If possible, please state why- if you recommend against


I haven’t been able to find much information on best practices to run multiple victron charge controllers with the same battery bank-


thanks

Chris


AC PV Coupling
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2 Answers
seb71 avatar image
seb71 answered ·

Don't do this.

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wkirby avatar image
wkirby answered ·

You should keep runs to the negative bus bar short and have the bus bar a the single star connection.
If you common two negatives on the end of another long run that you are creating another star point, you'll probably end up with a lot of noise in that cable.

Common the MPPT Battery negative connections at the single bus bar.
Run separate positive and negative cables from the MPPT to each separate PV array. This way there will be no ground loops.

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