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Posted By Topic: Solar/PV installations

Nickg
Mar 07 2018 13:20

I recently attended a job to complete an electrical inspection for PV installation at a domestic dwelling. The installation consisted of 18 panels connected in series (one string) which was run in HD conduit and connected to a 10kw inverter. Each PV panel had a power optimizer/DC conditioning unit connected to it. Due to this arrangement, the DC circuit had an open circuit voltage of 18 volts DC and an operating voltage when connected to the inverter of approximately 750 volts DC.

I haven\'t come across an arrangement like this in the past. My first thought is the install doesn\'t comply with AS/NZS:5033 due to the voltage exceeding 600 volts DC within a domestic dwelling. The fact that the open circuit voltage is lower than this, due to the connection of DC conditioning units, as far as I can tell still does not omit it from this point. Am I viewing this correctly?

The electrician advised me he initially set up the install with two strings of nine connected in parallel. However found the inverter wouldn\'t operate. He contacted the supplier, who advised the inverter required higher voltage (>600V) in order to operate. My thoughts are this inverter shouldn\'t be used on domestic properties?

Any thoughts much appreciated

Thanks
   

pluto
Mar 07 2018 16:02

Nickg Mar 07 2018 13:20
your comment 1
I recently attended a job to complete an electrical inspection for PV installation at a domestic dwelling. The installation consisted of 18 panels connected in series (one string) which was run in HD conduit and connected to a 10kw inverter. Each PV panel had a power optimizer/DC conditioning unit connected to it. Due to this arrangement, the DC circuit had an open circuit voltage of 18 volts DC and an operating voltage when connected to the inverter of approximately 750 volts DC.

I haven\'t come across an arrangement like this in the past. My first thought is the install doesn\'t comply with AS/NZS:5033 due to the voltage exceeding 600 volts DC within a domestic dwelling. The fact that the open circuit voltage is lower than this, due to the connection of DC conditioning units, as far as I can tell still does not omit it from this point. Am I viewing this correctly?

My comment 2
Using the cited standard AS/NZS 5033:2012 there is a 600 Volt d.c. maximum limit for domestic PV arrays.

Your comment 2
The electrician advised me he initially set up the install with two strings of nine connected in parallel. However found the inverter wouldn\'t operate. He contacted the supplier, who advised the inverter required higher voltage (>600V) in order to operate. My thoughts are this inverter shouldn\'t be used on domestic properties?

My comment 2
AS/NZS 5033 is currently being amended it is being proposed to remove the 600 Volt limit for domestic PV arrays.

However there are some further requirements yet to be developed for additional screening of live parts to allow the maximum limit to be raised. Until this development work completed and approved for use the only solution to is to use an inverter able to operate on a 600 volt maximum supply. Final approval of the proposal is some months away when the standard has been open for public comment and is forally approved for publication.


   

Nickg
Mar 07 2018 21:55

Okay. Thanks for the feedback.
   

AlecK
Mar 08 2018 00:31

in other words:
Under current rules, this installation is non-compliant