PV Installation Three Phase Guidance

[Nickyrox]

Advice on Three Phase PV Installtions

 

[i=p/u]

try pv forum in this site, maybe have a search. wont let me add the file i saved

 

[Markc]

I need some advice on Three Phase PV Installtions
When I did my PV course They never gave me any guidance in Three phase.
I want to make sure I design a new three phase installation correct.
The install I want to design Consists Of three inverters,one for each phase.
Can anyone please give me some Guidance on this sort of system?.

Cheers Nicky

We have done a system just like it. Treat it as three, single systems. Three inverters & sets of isolation and three generation meters. Keep it under 3.6Kw and its a straight forward job over that and DNO is involved (At cost) We also fitted a small three phase board with only three single pole MCB's as a point of connection into the existing system.

 

[Nickyrox]

Hi Mark,
Do you mean 3.6kw for the whole system as 3 or each single system output?
Was they put on 16a MCB's?.
How did you connect to the exsisting system?
Cheers
Nicky

 

[SolarCity]

You can have 3.6kW per phase and 16A breakers should be fine.

I think what Mark suggests is a good idea - a seperate 3 phase board which can then be connected directly to the incoming tails.

 

[Nickyrox]

On this project The 3 arrays are going on an out building . Now the main 3 Phase Board right by the 3 phase incoming is about 50 meters away. Coming off of that board on a 3 pole 45a breaker is another small 3 phase board with a few CCT's on it. That Board is about 6 meters away from the arrays. I Think it is run in 16mm swa to the this board.I wiil find out all of the correct details tomorrow.
Is it a possibillitie to install my 3x 16a MCBs in the smaller board.
Also what about RCD protection,How can this be acheived if the 3 phase is not RCD protected.
And I take it I won't need G59 relay protection on this sort of 3 phase install.
Thanks for all your help guys..

 

[SolarCity]

I see no reason why you can't connect to the existing board if there is room.

Why do you need RCD protection? If you must use RCDs then you could have problems getting the right type - it's best to avoid it if you can.

You won't need relay protection as this install will fall under G83.

 

[i=p/u]

hi folks, could you give me the a little info on the actual power you get from these systems , i see 3.6kw but do you actually get the full 15 amps of power during the day.. just a we cost run down if ya could .... thanks

 

[Markc]

Hi Mark,
Do you mean 3.6kw for the whole system as 3 or each single system output?
Was they put on 16a MCB's?.
How did you connect to the exsisting system?
Cheers
Nicky

3.6Kw per phase. Treat it as three individual installations. 3 notification to DNO.
Once 3 x 16amp circuits connected into a three phase board we supplied we made one three phase connection into the existing installation. We did this as a 125A sub main so the remainder three phase ways can be used. Think about a standard single phase installation just three times. 3 inverters, 3 generation meters and 3 connections.

Use inverters with transformers as this will do away with the need for RCD protection. If not a RCD will have to be a Class B at about £70 each. again x 3!

 

[Markc]

hi folks, could you give me the a little info on the actual power you get from these systems , i see 3.6kw but do you actually get the full 15 amps of power during the day.. just a we cost run down if ya could .... thanks

3.6Kw is peak not sustained. It is possible to achieve maximum output but for what length of time? Slight cloud will reduce performance hence why all systems are rated to their annual kWh rather than amperage or wattage. This could return approximately 3100Kwh (without working it all out)

 

[i=p/u]

kk.. so what would it cost for one of these systems, say in a domestic property and how long would it take to pay for itself,,,,,estimation cheers

 

[SolarCity]

3.6Kw per phase. Treat it as three individual installations. 3 notification to DNO.

3 notifications to the DNO? Is this how it works? With 3 seperate incomes for the consumer?

 

[Markc]

3 notifications to the DNO? Is this how it works? With 3 seperate incomes for the consumer?

It's exactly how we were told to do it by EDF and it's exactly what we done. Never heard anything back! Considering what things are going on with EDF or UK Power Networks I will check again before doing it again and I would strongly recommend checking with your own DNO's before installing. After all it isn't like they move the goal posts on us is it?

Remember it isn't the MCS notification! One cheque one overall system but to fall into G83/1 - 3 notifications to same DNO! Ridiculous I know as all three forms read the same (other than phase which I wrote on as additional information but didn't have to!)

 

[SolarCity]

We've got a couple of 3 phase installs lined up - I'll run them both by the DNO before we start just to be sure.

The more I read about DNOs, the more I'm convinced that anything that is even slightly out of the ordinary needs to be run past them first. Things can change quickly.

 

[Nickyrox]

Thanks for your replys fellas.
I have been a bit too busy to reply to you.
I am going to find out a bit more info on this install.
I will let you know the outcome.

Just to change the subject,does anyone know what they mean by "Annex-2 oc" in the sun box on the PV commisoning sheets?