Laurens D avatar image
Laurens D asked

ESS Self consumption Multiplus II GX


I would love to jump into the Victron economy because I'm myself from Netherland and I hear only good things about these devices; I do have some questions though.

I would like to create a pure energy storage system where I can charge my system with my specific triggers (on/off), and be capable to let the ESS run in self consumption where it will assist my AC loads.

I want to connect this to my public grid so it can assist in my whole home when using loads; so that it will use my battery's first.

My questions:

1. ^ Is the MultiPlus II the correct device for those tasks?

2. ^ Will it be possible to do those tasks without an AC Sensor?

3. What happens when a black-out happens and the load on the grid/ac side is 3500 watt while the MultiPlus can only deliver 3000 watt? are there functionality so that it'll be shutdown and remain safe?

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1 Answer
Jason - UK avatar image
Jason - UK answered ·

@Laurens D In short, yes, Victron would be a good system for you. I have a Multiplus II GX 5kva unit connected to 4 5kwh batteries. For about 7 months of the year from spring to autumn, my solar PV system charges the batteries enough that I am self sufficient for everything inc cooking and hot water generation via a heat pump and cylinder. For the other 5 months over the winter, I charge my batteries on cheat rate electricity during the night. Also during the night I do my hot water generation so during the day my batteries only have to power general household loads, cooking and heating. My energy bill per month is about £10 not allowing for any energy I export. In answer to your questions,

1. Yes, you would want a Multiplus II with a separate GX device or alternatively you can have a Multiplus II GX so everything is contained within a single unit. The GX part is the brains.

2. Yes, the multiplus II has a CT sensor on the ACin connection. You also have the option of plugging in a remote AC sensor to connect to your incoming mains power cables if you wanted to provide power assist to loads on the AC in side of the inverter.

3. In the event of a power cut, a constant load of 3500w would be too much for the 3kva unit as 3kva is about 2400w. I have a 5kva unit and I can sustain a load of about 4.4kW. The things that affect the kw output of the unit are the power factor and the ambient temperature. 1668416557082.png

I have a power factor in my house on about 0.9 due to having a lot of inductive loads.

Below is a like to my installation on VRM. In the photos section you will see what it looks like when installed but also I have a schematic (work in progress) of my system.

1668416557082.png (148.5 KiB)
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Laurens D avatar image Laurens D commented ·

Whoah! That is a nice setup you got there! It's nice that you can use your batteries to gain the maximum profit :)

There are a lot of restrictions regarding space in my home, so where the battery is stored is a few meter away so I cannot add a external sensor (unless it's in the same room); would this be a issue for the CT Sensor?

Yeah, I always keep confusing that, I have a 48v/3000kv system on the way to my home, I will be receiving this soon, I don't expect there to be much instances for a power outage considering in the Netherlands it has been really stable. But I would like to protect my device so I would love to know what will happen, in my opinion cannot deliver = out that's what I want, not that the device will burn out/break

Expecting my batteries near the 20th to my home, so then I can start with this project, I took the 3000kv/2400 watt model because I am not expecting to use > 2400 watt often, perhaps only when cooking, I still have gas in my home for heating.

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Jason - UK avatar image Jason - UK Laurens D commented ·

@Laurens D If you overload the unit during a power cut, it will shut down to protect itself eventually.

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Laurens D avatar image Laurens D Jason - UK commented ·

Thank you Jason, I know enough =)

Made this the best awnser and gifted you.

Good luck with your build, looks awesome

1 Like 1 ·