question

Elimac avatar image
Elimac asked

Using PowerAssist

I would like to know if are there any counter-indications about the way I plan to use PowerAssist.

My main goal is to run washing machine (2000W) + some permanent loads around ~300W. So, in total, on average I would like to run ~2300W during washing machine's program.

I have an inverter Multiplus 24/ 3000 VA, capable of delivering ~2000W, but with temperature derate sometmes I get overload warnings around 1800W or 1900W. I have around 3000W of PV. The idea is to take advantage of sunny days and put the system to work, with priority to solar and getting from GRID that small amount the inverter can't provide. This, without ESS for the moment.


So, I have set on Venus these conditions:

1. If AC load on inverter > 1700W, switch to GRID

2. Maxium AC input from GRID = 3A

3. Disconnect from grid when AC load < 1000W


This will force PowerAssist to work, giving roughly 700W from grid and 1700W (max) from Inverter (Solar/ Battery). During periods of 20 ~30 minutes.

This will save me a lot of € in power bill, while not overloading the Multiplus.

Is this ok? Or am I violating any rule? I don't want to jeopardy the Multi in any way...




MultiPlus Quattro Inverter Chargerpowerassist
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1 Answer
boekel avatar image
boekel answered ·

This is difficult to get working, mainly because of the time it takes to connect to the grid (the inverter has to synchronize the phase and voltage before it can do this)

so in practice you can have an overload situation before the system connects to grid.

Why do you want to do this? is it not allowed to feed back into grid in your location?

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Elimac avatar image Elimac commented ·

I already tested it, it works, but there is a noticeable delay before it switches - around 5 seconds. But that's why I've set the threshold at 1700W, this way it shouldn't overload.

In my location I only have trouble if I feedback to grid - no income and I get legal stuff to be involved with. I prefer to use almost as backup of my "near-off grid" system. The origin of my installation had to do with poor service, constant grid failures, electronic devices that suffered from grid spikes and professional need of reliable power when working at home. I invested in the system to be near-independent, but also want to have some return, hence the desire to use grid as low as possible.

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boekel avatar image boekel ♦ Elimac commented ·

good to hear, if the connection speed is no problem then: perfect.

Usually these sort of systems are configured to be able to provide all the loads without grid-support. if budget is small an option is to have some big loads directly on the grid, and important loads behind the inverter.

Also when grid is very poor / or even dangerous: you might want to use a separate charger to isolate your local grid from the mains.

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Bobby avatar image Bobby Elimac commented ·

Hi there, I just enabled Power Assist and it does what I wanted it to do, meaning when I need more then 4kw on my 5000va multiplus, it uses power from MPPT, Batteries and adds additional power from the grid.

Please can you tell me how do you set the threshold as I was unable to find that option?

I would also like for it to start pulling current from the grid earlier in order to avoid couple of seconds of "overload".

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Elimac avatar image Elimac Bobby commented ·

In Venus OS, select the Multiplus in main menu and then is this option:


Also, in my case, I'm using some assistants to force ignore/not ignore ACin, so this menu is also important:

Settings -> Generator Start/stop -> Settings -> Conditions

I needed some wiring between Venus GX and AUX relay in the Multi. This is working great. Since this post was originally written, I've added a 2nd Multi in parallel, so now I can have 3600W from solar at all times plus some 6Ax 230V from grid or more if I need to.



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Bobby avatar image Bobby Elimac commented ·

Ok, great...so I used some silly maths in order to try and calculate what (I believe) I want to achieve :)

I took 1700W / 6= 283.333

Then, I took 283.33 x 13.5 = 3825W

So, am I correct to say that when the load gets to this number (3825W), Victron should start taking power from the grid? (Power Assist is set to ON, so it is currently taking power from the grid when load gets to around 4000W)

Just to note that currently that option is on 50 (I think its Amps as its current?)

Thanks so much for helping me with this, its is much appreciated

Bobby

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Bobby avatar image Bobby Bobby commented ·

Ok, I can answer my own dilemma...I did set the Input current limit to 13.5 but that didn't change much.

I simulated and managed to put a load of around 5,3kw and Victron started pulling from the grid at around 4,3kw load. It was in overload for around 1-2 seconds...

So I did not manage to lower the load threshold that would instruct Victron to start getting power from the grid.

I will play some more with that setting and advise should I find any way of controlling it

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Elimac avatar image Elimac Bobby commented ·

Try to use Virtual switch in VEconfig "Ignore AC input" and then play with the settings to conect/disconnect from grid based on load power.

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Bobby avatar image Bobby Elimac commented ·

I am using ESS due to my system so I am not able to use Virtual switch.

I basically have MPPT, 48V Battery Bank (Gel batteries but I take only 20% of the bank, I don't cycle them more then that) and grid power connected.
During the day I use MPPT/Battery and at night I use the grid.

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