sylk avatar image
sylk asked

MP II 5000 passthrough MP 1200

Hello everyone!

I have an offgrid system with a 48v multiplus 1200, no grid power at all.

Recently i installed a 3Kw water heater and bought a Multiplus II 48v 5000, wich i want to install on the same battery bank as 1200.

I want to keep using the 1200 all the time, and the 5000 to be wired to Ac-in to the 1200, in standby, and pass through it power when the heater is turned on, or the power needed exceeds 1200s capabilities. Is this possible?

I have a venus gx, do i need to connect the 5000 to it, or leave it it as a "dumb" generator?

Also, a generator can be connected only to multiplus 5000, right?

Thank you!

Multiplus-IImultiplus in parallel
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2 Answers
dirtyfrank avatar image
dirtyfrank answered ·


I've got a similar setup. I'd recommend to do it the other way round. I.e. first the MP 1200 with the MP 5000 connected to its output and thus the loads on the output of the MP 5000. The MP 5000 has to be set up to just power assist - nothing more. That way it is in passthrough for most of the time and only kicks in when the MP 1200 is overloaded. You will have to determine the necessary setting for the input current limit so that the MP 1200 is not overloaded. In order to optimize efficiency a distribution of the loads to both of the MPs might be advantageous. I'm using a bash script on my Venus to achieve this and dynamically adjust input current limits depending on the required power for the loads (thus a permanent connection to the Venus is required). It might be possible to do that with the assistant for input current limit (not dynamically but only in 2 steps which in your case should be sufficient).

In doing the latter you won't need to connect the MP 5000 to a Venus device (except for initial configuration).

A generator can be connected to the AcIn of any MultiPlus. You should always configure the AcIn accordingly (in Remote Console).

There is one disadvantage though. The passthrough permanently consumes a little bit of additional energy in order to enable instant power assisting. That might be somewhat between 5 and 10 Watts for the MP 5000. You'll have to check the exact value for your device and setup yourself. Considering the advantages this is imo a small price to pay.

Furthermore the MP 5000 might sometimes disconnect for a couple of seconds when loads with high startup currents cause the voltage of the MP 1200 to drop below the disconnect threshold. That`s why I don't recommend turning on the UPS function of the MP 5000.

Please ask if you need guidance for the proper setup in VE.configure.

Have fun!

So long,


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semlohnhoj avatar image
semlohnhoj answered ·

Checkout this Andy's YouTube channel. He has done something similar with a MultiplusII and a Phoenix inverter.

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