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Posted By Topic: Roof Top Isolators for 230 V Micro Inverter Arrays

Mar 02 2019 18:50

Learned ones! within AS/NZ3000 re isolating sw adjacent to generating source can we cite a lockable remote isolator to satisfy
this particular situation?

I think we can agree no one is going to get up on the roof with a 27 degree plus pitch to go and try and find the AC rooftop isolator under the array somewhere.

A lockable isolator somewhere between the array and switchboard (and labelled at switchboard) connection is a far practical arrangement.

Mar 02 2019 19:43

I would suggest that a rooftop isolator is essential if it necessary to change a faulty module as the wiring loom amd the connetion to each mirco-modules used is not one designed to be removed when enlivened.

If you check with the mirco-module manufacturers instructions I think you may find that a new module and is connected to a PV panel and operating cannot be connected to the common loom when it is enlivened from other modules. The roof top isolator provides a easy method of diconnection for rstarting all modules together and thus will re-synch all modules as a group of modules.

Mar 02 2019 20:04

A remote lockable remote isolator would satisfy your mentioned concerns.

By having an isolator at the rooftop does not mitigate a micro inverter islanding within the array on the load side of the rooftop isolator .

The question Im asking is does a remote lockable isolator satisfy AS/NZS 3000 with regard to an isolator adjacent to a generating source.

Mar 02 2019 20:10

Im also suggesting solar arrays at greater than 25 degree pitch especially during winter when dew is present etc that the "readily accessible" is a crock of the proverbial especially when there is no mandatory signage to highlight where the isolator is located.
The labelled (at inverter connected switchboard) remote lockable is just common sense.

Mar 03 2019 12:01

Short answer is "No".
The requirement [ that the switch be "adjacent to, or on the generation system". Further, there must be clear line of sight between switch and system.
Which is about the person operating the switch being able to see that there's no-one working on the system.

For those whose dictionaries are made of elastic words; 2018 edition defines "adjacent" as within arm's reach and without any obstruction between, so suggested location " under the array" would not comply.

Fact is that someone WILL be up there to carry out work on the array, no matter how steep the roof / array pitch; and that's when the switch is needed.

Mar 03 2019 12:10

At the edge of the array under the module is readily accessible once on the roof.

The fact that its on the roof is note readily accessible by definition.

Mar 04 2019 07:16

Hi AlecK,

Clause ends with the word "or". That word suggests an acceptable alternative exists.

It looks like if we follow the provisions of clause then the switch does not need to be adjacent to the array.

Could the switch not be some distance away with a provision of being locked in the open position?

Mar 04 2019 09:23

True; and that acceptable alternative" is given in (a)(ii).
But it's a little more complicated that just capable of being locked off, as that's a requirement for any isolating switch under Note the different wording used for this item: "provided with a means of securing ... that requires a deliberate action to engage or disengage".

The second bit seems easy enough, hard to think of a means of "securing in open position" [] that wouldn't require "deliberate action" when locking / unlocking.
"Provided with" means not just a hole for the padlock (or whatever) the actual lock has to be "provided".

Part of the problem is that 7.3 is based on the requirements for engine-driven generating sets (found in "3010"); and doesn't cater well for other forms of generation. In particular, array-mounted micro-inverters hadn't been invented when 7.3 was written. In most cases, we should be using the appropriate companion Standard, which in this case would be 4777.1. And even then, need to get latest (2016, AS/NZS - not yet cited) edition for any guidance on micro-inverters

Mar 04 2019 11:45

You also need AS/NZS 5033 2014 edition clause to get the full story on the installation of micro inverters.