question

crop61 avatar image
crop61 asked

parallel multiplus 2

I have a multiplus 1, 48/5000. I have had this charging my lithium battery bank for several years and it has been super reliable. In the summer I charge my battery from my solar and in winter I charge the battery from night rate electricity. I have recently expanded my battery to 50kwh and in the 7 hours of night electricity the single inverter does not have time to charge the battery, so i decided to get 2 48/5000 multiplus II and connect in parallel. Using the exact same cable that connects the original multi and the same colour control I connected the 2 multi's and set them up a parallel. Every time I turn these on after about 30 seconds my RCD trips. Anyone any ideas. I am confident the parallel setup is correct as I work with these inverters every day, but could do with some help to fix this issue.

rcd tripping
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4 Answers
derrick thomas avatar image
derrick thomas answered ·

Have you updated the firmwares in the multi's? Completed the configuration setup?

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iammotorhomeless avatar image
iammotorhomeless answered ·

@crop61 what is the rating of the RCD

it could be DC voltage ripple
or a ground wire problem

I just have 2 thermal breakers (one to each unit) and the RCBO's are on the house side of the units

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spazpeker avatar image
spazpeker answered ·

I have the same setup, my RCD also tripped replaced it with a 100ma time delay RCD, the inverter feeds consumer unit with RCBO’s

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electrical-revolution avatar image
electrical-revolution answered ·

Are both AC cables from each inverter the same length and the same type, IE both 4mm each or both 6mm each or both the same type of cable IE flex or TPS etc.

It's super important to have both cables exactly the same when working in parallel due to resistance in the cable will cause problems like RCD tripping.

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