Three Phase install,3x sma inverters.With G59 relay

[Nickyrox]

Proposed Install
Inverters are sunny boy SMC 9000 TLS-20
Each inverter has three strings of 14 230w = 126 modules
The system is around 28KW
G59 Protection is required.
I was thinking of wiring each seperate array with the 3 strings in a junction box in paralell to each inverter so only one dc isolator per inveterter would be rquired.
I know you can plug the three seperate strings directly into there own individuale plug connections in the inverter,But then I would need 3x dc isolators per inveterter.
So would the first option be acceptable.
If I come out of a junction box with one set of wires going to the inverter,would I need to use 10mm cable fom that point to the inverter due to amount of power coming from the 3 strings?
Has anyone ever installed a G59 relay,if so do you have any good advice on the installtion method or a good model to use.

The intallation is Three phase but does not have a three phase board to connect to.
Just a single phase board and a large isolator that feeds a couple of other points..
Any suggestions please.

 

[edexlab]

You could do the configuration of strings but you would need to use combiner boxes these are dc isolators / string fuses / surge protection string/ cable terminals all in one,

but they're not cheap and then you have to run a main cable (i have'nt worked out size as length /current unknown ) I think this would be more expensive and complicates a fairly straight forward job ,and you would need a G59 relay on top ,you can get these ready made ,calibrated and incorporated into a three phase board again they're not cheap

Alternatively this design could be done using 2 sma 15000tl stp (depending on system spec, which modules etc) which have G59 certification ,
no need for separate relay as i understand

you would need separate isolators at the inverter as the string configuration would have two strings of equal size and one smaller, on each inverter so you could'nt combine them into one box and use a main cable to inverter, but bearing in mind the cost of this size of system 6 isolators per inverter is a small amount really.