Grounding for hybrid system

[David947]

I'm working on a residential hybrid solar system where the house AC circuit is already earth grounded and connected to one rod. I'm having 9 strings of 8 panels in series, each string is connected to an SPD and the ground coming out of it is connected to the house main AC panel grounding busbar. My question is for grounding the solar panels mounts and frames, is it ok to connect this ground wire to the house main AC panel busbar?
I'm having a hard time deciding as the topic is confusing and I already found conflicted analyses.
Thank you.

 

[zanydroid]

I'm working on a residential hybrid solar system where the house AC circuit is already earth grounded and connected to one rod. I'm having 9 strings of 8 panels in series, each string is connected to an SPD and the ground coming out of it is connected to the house main AC panel grounding busbar. My question is for grounding the solar panels mounts and frames, is it ok to connect this ground wire to the house main AC panel busbar?
I'm having a hard time deciding as the topic is confusing and I already found conflicted analyses.
Thank you.

That is the orthodox, canonical way. IMO there isn’t really a decision to be had other than whether you want to bond directly to GEC or indirectly, and whether you want take the allowance to route the EGC/GEC in a separate path (but same starting and ending location of array and ground bar/GEC)

What other options were you thinking about?

There’s not really another way to dissipate induced AC within the frames from the inverter/charger/non-isolated MPPT path.

And electrical code requires all metal components like that to be bonded to ground. The DC and AC side are the same system due in part to the non isolated inverter design

 

[David947]

That is the orthodox, canonical way. IMO there isn’t really a decision to be had other than whether you want to bond directly to GEC or indirectly, and whether you want take the allowance to route the EGC/GEC in a separate path (but same starting and ending location of array and ground bar/GEC)

What other options were you thinking about?

There’s not really another way to dissipate induced AC within the frames from the inverter/charger/non-isolated MPPT path.

And electrical code requires all metal components like that to be bonded to ground. The DC and AC side are the same system due in part to the non isolated inverter design

As another option I read that it's possible to have another rod dedicated to grounding frame mounts only and bound it with the main rod.

 

[zanydroid]

As another option I read that it's possible to have another rod dedicated to grounding frame mounts only and bound it with the main rod.

Sort of. A lot of people here subscribe to the Mike Holt analysis where that is strictly worse. That adds the failure mode where the array’s grounding system picks up voltage gradient built up in the earth between the structure and the array and happily delivers it across the grounding system.

If you don’t drive a grounding system at the array then this won’t happen.

I believe most people expect the ground rod to be a strict improvement by giving a second path to dissipate charge built up on the array. But that doesn’t come for free.

I dont know how the probabilities compare but the soil is a much bigger target for accumulating funny business than an array.

 

[David947]

Sort of. A lot of people here subscribe to the Mike Holt analysis where that is strictly worse. That adds the failure mode where the array’s grounding system picks up voltage gradient built up in the earth between the structure and the array and happily delivers it across the grounding system.

If you don’t drive a grounding system at the array then this won’t happen.

I believe most people expect the ground rod to be a strict improvement by giving a second path to dissipate charge built up on the array. But that doesn’t come for free.

I dont know how the probabilities compare but the soil is a much bigger target for accumulating funny business than an array.

Thank you for clarifying this topic.