Bonding of DC System Cable Trays

I'm working on designing a PV plant where we have around 20 inverters each connected to a number of strings.

The grounding cable for each string runs along with the power cable of the same string according to NEC requirements. The different grounding cables of different strings connected to the same inverter are all connected together to a grounding box next to the inverter and a common ground is connected between this box and the inverter (since the inverter can only take one grounding cable).

We are combining different DC circuits from different strings connected to different inverters in one cable tray and we are providing grounding jumpers across the tray sections.

The question here is: Where the cable tray grounding will be connected? Since the tray serves different inverters, I'm not sure if it will be acceptable to connect the tray grounding to one of the inverters or should we provide common grounding.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I'm working on designing a PV plant where we have around 20 inverters each connected to a number of strings.

The grounding cable for each string runs along with the power cable of the same string according to NEC requirements. The different grounding cables of different strings connected to the same inverter are all connected together to a grounding box next to the inverter and a common ground is connected between this box and the inverter (since the inverter can only take one grounding cable).

We are combining different DC circuits from different strings connected to different inverters in one cable tray and we are providing grounding jumpers across the tray sections.

The question here is: Where the cable tray grounding will be connected? Since the tray serves different inverters, I'm not sure if it will be acceptable to connect the tray grounding to one of the inverters or should we provide common grounding.
I think I would bond it to building ground.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
To elaborate, all the inverter ground terminals and the cable tray should be bonded to each other and also somehow to the building ground.
Keeping in mind when sizing and routing that there is usually only one Ground Electrode Conductor and multiple Bonding Jumpers supplementing it, even when there are multiple ground electrodes.
 
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