Do i need to install a DC isolator if theres already one provided on the hybrid inverter?

[Lassrguy]

Hi, I have nearly finished installing my first solar system for my brother in law. havent installed a DC isolator on the string lines (none in stock locally and didnt order ahead). The sofar inverter he bought has a rotary isolator fitted already.

Can I label that isolator and be compliant with BS7671. I am registered but do not have mcs.

Many thanks.

 

[swaRRR]

It's one of those grey areas. Good practice to have a separate isolator imo.

Reason being without one you're left with an inverter that has a live source going directly into it. I've seen AC backfeed into the DC isolator when the inverter has been faulty. I've also seen the + and - strings when plugged directly into the inverter, when there's been an inverter isolator fault, create a mini circuit which has arced and literally melted the MC4's as they were pulled for some testing.

Just better to have the 30 quid isolator separate so you know you've completely separated the juice from the system. The isolator should be local to the installation as well and not eg in a separate room somewhere.

EDIT to give my reasoning.

 

[Lassrguy]

It's one of those grey areas. Good practice to have a separate isolator imo.

Reason being without one you're left with an inverter that has a live source going directly into it. I've seen AC backfeed into the DC isolator when the inverter has been faulty. I've also seen the + and - strings when plugged directly into the inverter, when there's been an inverter isolator fault, create a mini circuit which has arced and literally melted the MC4's as they were pulled for some testing.

Just better to have the 30 quid isolator separate so you know you've completely separated the juice from the system. The isolator should be local to the installation as well and not eg in a separate room somewhere.

EDIT to give my reasoning.

Many thanks. Makes sense to protect the inverter and not put other engineers in an uncomfortable position, if someone else needs to do maintenance in the future.

 

[richy3333]

No you dont. Just label the inverter accordingly

 

[littlespark]

I’m not an installer, but I would think if anyone had to work on or replace the inverter at any time, it would be safer to do it with an external isolator on both the AC and DC sides.

Whether the inverter itself had one or not.