question

Hi @PieterE,

Presuming that everything is correctly configured (specifically the PV inverter assistant) then the Multi will raise the frequency on the AC output until the PV inverter stops providing power.

If i disable the "AC input control" option, the multi swiches the solar invertor off (done by using a assistant). This works fine.

Do i switch the "AC input control" option to on, then it seems to work until the batteries are full, and the solar produces more then the multi can use. Then instead of raising the frequncy the system go's into overload and switches completely off whithout raising the freqncy. And anyway, my target is to in that case then connect to the grid and dump te power there.

I have been testing with almost all the assistants by now but non of them do the thing i want.

All i acually want is for the multi to disconnect from the grid and discharge the battery up to a certain point. (Using the solar-invertor input and battery for the load (and battery charging when there is power avaliable). Then reconnect to the grid if there is power "left over" to dump this power into the grid. The "AC input control" option lookt like it is accactly what i want but i need one extra option: reconnect when the connected solar invertor (connected to the output of the victron) is delivering more power then the multi can handle (batteries full and sun is shining).

It makes me go bonkers that i cannot find a simple solution for this.

Maybe i should go with my original plan: disconnecting the grid from the multi using a relay, then waiting for the frequency to go up on the ups side of the multi (indicating the multi wants to shut off the solar invertor) (i can program this in a micro computer) and then connecting the multi again. But i understand that the multi should be capable of doing this all by itself. But i have been testing for weeks now, and can not get it to work.

Summary:

- I have a solar invertor connected to the multi ups site

- I want the multi to disconnect from the grid and use batteries until SOC gets to a certain point. (Charging if possible from the connected solar in the mean time)

-When the batteries and my loads can take less then the solar invertor pruduces, dump the rest in the grid.

Should be fairly simpel, but i can not find out how to do it. And it makes me realy question if i have bought the right invertor. Grrr, makes me go bonkers ;-)

Could you help?

Pieter

Hi isnt jus ESS what you want? PV charge batteries, power load and surpluss to grid

Not realy. I have tried ESS but as far as i can tell it does not have the functionallity i need. Where i live we are going to pay for delivering electricity back to the grid. So i want to use as much of it for myself first. I wand to use the battery in the night, and then when the solar starts it recharges the batteries first and/or delivers electricity to the connected devices. Then when the battery gets to a certain SOC and there is to much solar, i need it to connect to the grid to dump the rest. We get paid 5 cents per kWh and we pay a penalty of 3 cents or so. So i get pays 2 cents or so per kWh. Thats is why i want to use as mutch myzelf as i can. The usage if the battery at night would make it possible to "shift" the solar power from the day to the night. I an sure a devie like the multiplus ii sghould be able to do that. But i can not for the life of me find out how to do that. I had hoped that activating "AC input control" would work, but as soon as the battry is full and the solar produces more that the multi can handle it just switches off the multi copletely. If i disable "AC input control", then an assistant raises the frequncy and switches off the solar. Nor what i want, but at least it does not put me in the dark. Somehow "AC input control" disbles the assistant.

Any advice?

Pieter

Hi,

I have a MultiPlus-II GX with only ESS assistant and it works the way you want it.
PV power goes to AC load, extra PV power charges the battery.
When SoC is 100% the PV power goes to AC load and the grid.

Ok, i am very interested. I could not get it to work. And i should be able to (my background is programming). Would you mind telling me what your settings are? Or if this is a lot of work, is it possible you send me your config files so i can inspect and 'dry' test it here? I do not think there are privicy things in there, but i could be wrong. Maybe then also the settings for your ESS assistant?

I have spend so many hours on this, that i almost were giving up. I think that somehow my brain keeps going the wrong way and i might not see the clear road before me.

Could you help?

Pieter

P.S. I only have the Multiplus II, no screen connected. I have to do everything through a connected laptop via MK3 and victron software.

>> You dont have a GX device like a cerbo?

No i do not.

Then i have 2 options i think. Either create my own system, using a relay to disconnect/connect the multi and/or solar from the grid, or to start reading about the Cerbo. ;-)

With a disconnected (from the grid) multi i could monitor the frequency on the output of the multi, if it go's up then the multi is trying to stop the solar meaning it gets more energy then i can handle. As soon as this happens i can connect the multi to the grid.

Because of the frequncy difference the multi will then first switch off the solar (i expect), and then connect to the grid when i has sinc't the frequency with the grid. After that the solar will reconnect after a minute or so and start delivering energy to the grid via the multi.

I do then have to find a way to signal to my micro computer when the batteries have reached a certain SOC.... But connecting yet another battery voltage device and interfacing with that is rather cumbersome.

Not to difficult to make, but i rather have it all done by the multi.....

I thank you for your time in helping me. If you have anything to add please do. If a decide for the cerbo, what add on devices would you advice? I'm open for everything and learning every day.

Pieter

hee, thanks, it turns out i will have to do a lot more reading before i get this to work.

Thanks for your time.

Pieter