Multiplus II and changeover switch

Hi all,

I recently installed 3kva Multiplus II for loadshedding backup. When the changeover switch is on inverter state, essential loads are run from the inverter even when Eskom is available. I expected Eskom essential loads to run on Eskom and inverter to only kick in during loadshedding. What am I missing?

Changeover is really there to switch the power sources from Inverter to Eskom, when the inverter is off, in for repairs or whatnot.

The rest of the time, if Eskom is on, both the DBs, critical and non-critical, are fed from the inverter, to save you money.

Thanks for your reply @TheTerribleTriplet, you and I have had this discussion offline but it’s still not clear to me. According to the attached diagram (not mine), the changeover can either switch between Eskom or inverter, not both. My thinking is that you need some “intelligence” from the inverter to “instruct” Eskom to take on all or some of the essential loads. I believe Multiplus II has this capability but does it come by default from the factory or does it need to be programmed?

What TTT said is correct. The manual switch over in your DB is for when you need to service the inverter and want to bypass it.

But the settings for your inverter will also influence how it will apply the power. If you want to use it as a UPS, then you need to change the mode under ESS (Energy Storage System) settings to Keep batteries charged. If it is on one of the Optimised settings is will try and save you money and use your PV power (if you have) and batteries to save you money. Then there is a setting called Min SOC which is the min SOC % that you want te batteries to deplete to in this saving money mode.

Normally in loadshedding times I would increase my Min SOC value so that more power is left in the batteries and there is less used for saving money.

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Thanks @Louisvdw, I think that answers my question. I have placed order an order MK3-VE.Bus to USB cable to do the settings.

You can do it all via the Victron portal, don’t need a MK3 anymore.

Today, the only time I have needed an MK3, was when an inverter’s firmware was so old, it had to be done manually, using the cable.

Or when you use a Rpi for the Venus OS.

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Wow that great news, means I can save R1200! I have a Cerbo Gx connected to the ET112. For Multiplus to Cerbo, I need RJ45 cable, right? What cable do I need for BMV700 to Cerbo? ET112 is currently connected on the output of the changeover switch, is this the correct place?

Would VE.Direct to USB work to connect Multiplus with Cerbo?

Multiplus to Cerbo: Normal UTP network cable.
BMV700 to Cerbo: VE.Direct cable, not the USB one, just the plain one.
ET112: Must be connected after your main breaker on the main DB to measure at that point, what is drawn from Eskom, and to no feedback past that point.

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For the ET112 you need a RS485 converter which normally plug into the USB.
The rest like TTT mentioned.
If you have a Cerbo GX, then all the settings I mentioned in on the GX device. That is the brain.
You can review all the settings in the ESS manual 1. ESS Introduction & features

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Thanks gentlemen, will update as soon as I receive cables.