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hugo avatar image
hugo asked

When is anti islanding device NOT required?

I have a Quattro 10K and it doesn't have an internal anti islanding device and therefore I'm not allowed to have it grid tied in South Africa, unless I install an external anti islanding device.

My question is, if I need anti islanding when I configure the grid in VE Configure to "None"

I want to run a virtual switch and NOT the ESS, specifically to avoid the anti islanding device. In this case the safety for not feeding back to the grid is done by what is called an internal "AC input relay" or "Back feed relay" in the Multi, but I'm not sure about the Quattro and I'm particularly not sure if you also need the external anti islanding device

I run 99.9% of the time off grid, but want the grid available should the battery charge drop too much. This can be done by Virtual switch "Ignore AC" function until battery is too low, then it will use some grid power

I think it must use Loss of mains detection (LOM) and the internal relay, as apposed to external safety device


MultiPlus Quattro Inverter Chargergrid
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hugo avatar image hugo commented ·

My PV goes through MPPT charge controller to batteries only

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Paul B avatar image Paul B hugo commented ·

then you should be fine. set the grid to none and make sure the export is off in the ess and it will not export as far as I am aware.


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mihair answered ·

Internal Multi and Quattro anti-islanding isolation relay is not redundant and that is the main problem with implementation in most part of the word, not speed. AFAIK only in UK is not mandatory to have redundancy, hence two independent disconnecting relays

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hugo avatar image hugo commented ·

Ok thanks, but maybe I can phrase my question differently. I want to know if some systems don't have to have anti islanding (internal or external, no matter which country)

For instance, I know a completely off grid system wouldn't need it, because of no wiring between the grid and the inverter, so no chance of feeding back

Then there's the backup system, with inverter/charger, battery and a grid connection (like a UPS on your pc) The grid charges the battery and in case of power failure, the load is powered from the battery. Now does this system need anti islanding, to prevent your battery from feeding AC into the grid? It would mean my $ 100 office UPS is fitted with internal anti islanding system! Or maybe such a system is not considered to be "Grid tied" and therefore not required to have anti islanding?

Then there's the same system as above, but with solar panels to help the grid charge the battery, via MPPT charge controller, just on the DC side. I would think this system is also not "Grid tied", so wouldn't need extra anti islanding

Then all the rest of the systems where you are "grid tied" which would need anti islanding, since it always wants to be connected to the grid, whether feeding back or not

Somebody told me that if you are going to have wiring from the grid to your inverter, you must have anti islanding, no matter what you use it for and the only way to have no anti islanding, is to disconnect the wiring between the grid and the inverter! That would mean the Quattro can only be used in off grid systems, unless you add anti islanding


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nigelfxs avatar image nigelfxs hugo commented ·

I think the main difference between a UPS and the Quattro, from a wiring rules perspective, is that the Quattro is capable of feeding back to the grid. A regular UPS is different since it does not have any circuitry capable of generating power on its AC Input.

The wiring safety rules therefore require anti-islanding (with redundant relays) for any equipment that has the ability to feedback power on its AC-Input. Even if this feature is "disabled" in software.

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Paul B avatar image
Paul B answered ·

The Quattro works exactly the same as the Mutli in this area.

if you have it set to none then you may still need it, depending on how your PV is setup

you have not mentioned how your PV is connected

but keep in mind.

if the batteries are full 100% and the grid is connected and the PV inverters outputs are not turned off or reduced it will still export the extra PV power. thats why you are probably turning the grid off/on using the general flag I suspect.


the quattro has a form of anti Islanding in it and I use the grid selection OTHER, here were I am but its not super quick in the timing to turn off from export if there is a grid failure and thats when its needed, well thats what I have been told.

anyway if you use NONE then test it out and make sure you understand what it does and how it works in the real world, especially if you have grid tie PV connected on ac1 OUT


I am doing similar here but using the ess and the general flag and real on and relay off assistants plus the generator autostart in the CCGX/venus to turn the grid off and on when needed. plus I did change over to a multiplus II that now has it inbuilt

fun and games and still having some minor issues


hope the above is not to confusing

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hugo avatar image hugo commented ·

Thanks, my PV only charges the batteries through MPPT controller. Quattro running in inverter mode from batteries (and DC from PV when available during the day) permanently

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