My first 3 phase solar pv systems need help

[jon jordan]

Hi guys
need a little guidance on a install I got to do this week
we got a bungalow on a 3phase supply with 3phase cu
The kit we have is as follows
3 x inverters 3.6 growatts
1x 3 phase meter

i was thinking of taking a 3 phase supply to workshop Not far so thinking of 6mm swa
on a 3p mcb 16amp
to a 3ph cu then out from 16 amp mcb 3 pole to 3 phase isolator 20 amp to meter then to the inverters

any help on this would be great as its my first 3 phase install
cheers JonJon

 

[ian.settle1]

Hi guys
need a little guidance on a install I got to do this week
we got a bungalow on a 3phase supply with 3phase cu
The kit we have is as follows
3 x inverters 3.6 growatts
1x 3 phase meter

i was thinking of taking a 3 phase supply to workshop Not far so thinking of 6mm swa
on a 3p mcb 16amp
to a 3ph cu then out from 16 amp mcb 3 pole to 3 phase isolator 20 amp to meter then to the inverters

any help on this would be great as its my first 3 phase install
cheers JonJon

What's a growatt when it's at home?

 

[jon jordan]

That's the inverter manufacturers
austrailian I think

 

[jon jordan]

Is it ok to go from main 3phase house cu on 16amp 3 pole mcb to a
20 amp three pole & neutral isolator into meter. Then out to inverters
?...

 

[Gavin A]

I'd want to use a separate MCB for each phase / inverter, and separate single phase isolator per inverter.

so 16A 3 phase MCB >>> 3 phase meter >>> 4 pole isolator >>> 4 core and earth >>> distro board with 3 x single phase 16A MCB >>> single phase isolators x 3 >>> inverters x 3

or similar.

 

[jon jordan]

Thanks Gavin
so go down the cu route
can I ask why you put the meter & 4pole isolator before the sub 3phase board cheers Jon

16amp 3pole mcb --- swa --- adapt box--- meter-- 4pole iso --- 3phase cu 3 way --- 16amp mcbx3 --- 20amp isolatorsx3--- inverters

 

[atm84]

Thanks Gavin
so go down the cu route
can I ask why you put the meter & 4pole isolator before the sub 3phase board cheers Jon

16amp 3pole mcb --- swa --- adapt box--- meter-- 4pole iso --- 3phase cu 3 way --- 16amp mcbx3 --- 20amp isolatorsx3--- inverters

So that the meter is monitoring the whole sub board I imagine.

 

[jon jordan]

so what then happens when customer uses the spare ways on board for something else
wouldnt it be better just to meter from the cu to inverters ??

cheers jon

 

[Gavin A]

or similar.

this bit should answer your question, you're the system designer, you design it, but usually the meter would go near the main board - not always though, so design it how you think best suits the situation.

re the 2nd distro board, use a 3 way with single phase MCBs for each phase, and common neutral bar - the incoming cable is already protected at the main board, then you'd have no spare ways to worry about. Either that or label it up for solar only, if anyone ignores that in the future, then that's their look out, can't really legislate for idiots ignoring specific instructions.

 

[atm84]

or similar.

this bit should answer your question, you're the system designer, you design it, but usually the meter would go near the main board - not always though, so design it how you think best suits the situation.

re the 2nd distro board, use a 3 way with single phase MCBs for each phase, and common neutral bar - the incoming cable is already protected at the main board, then you'd have no spare ways to worry about. Either that or label it up for solar only, if anyone ignores that in the future, then that's their look out, can't really legislate for idiots ignoring specific instructions.

You need to include 25% spare capacity. Is that not in the regs somewhere? Can't be bothered to look at the mo but sure it was a reg that any new install shall have spare capacity.

 

[JD6400]

Hi ATM84 , I have not fully read this thread so apologise if I have the wrong end of the stick , so to speak !?
I think Gavin is suggesting that all the inverters are first fed in to a sub board and then back ? If so I would personally say it was bad practice to deliberately plan to leave spare ways ( possible parasitic loads ) , as it is only really being used to consolidate all of the inverter feeds into one for metering and possibly connecting a g59 protection relay .

 

[atm84]

Hi ATM84 , I have not fully read this thread so apologise if I have the wrong end of the stick , so to speak !?
I think Gavin is suggesting that all the inverters are first fed in to a sub board and then back ? If so I would personally say it was bad practice to deliberately plan to leave spare ways ( possible parasitic loads ) , as it is only really being used to consolidate all of the inverter feeds into one for metering and possibly connecting a g59 protection relay .

Thanks for your reply. Its good there are some ppl on here willing to help others and explain things.

 

[Gavin A]

You need to include 25% spare capacity. Is that not in the regs somewhere? Can't be bothered to look at the mo but sure it was a reg that any new install shall have spare capacity.

this isn't a sub board for use by anyone else for anything else, it'd be generation specific, and only allowed for use with that metered system if installed with the meter at the other end of the cable. Same principle as a FCU, just splitting down to 3 separate phases.

If there is likely to be a demand to use the cable / sub board for other purposes then the generation meter would need to be moved to the other side of the sub board, then you can leave as many spare ways as you want.