Farm Grid Connection Advice

[solarken]

I am designing a 72kW PV system for a farm. The service is 480V 3ph at a pole that is in the middle of three grain silos. There are several service feeds coming off the pole, and some via taps just before entering the weatherheads. There is an empty 2-inch conduit at the base of the pole that comes up just outside the building I am installing the array on. The conduit run is about 120ft. There is a 240V single phase loadcenter in the building that is fed from a transformer in a small electrical buidling about 20ft from the pole, but it is too small to land the inverter output on and would also require too many single phase inverters tom be installed. Instead, I am am planning on a 480V-3ph line side connection using a SquareD H363-NRB as the system disconnect, and mounting it either at the building side of the conduit, or the pole side of the conduit. I will have the electrician who routinely deals with changes at the pole service tap and extend the 480V to the disconnect. Questions I have:
Should I mount the disconnect near the building or near the pole?
Where do I need to drive a ground rod and how many, for either option?
I assume I will need to bond the neutral to ground in the disconnect only, and run the neutral and ground separately from the inverter to the disconnect. Is that correct?

I appreciate any advice you can give!

- Ken

 

[jaggedben]

You need a disconnect at both locations, in my opinion, or at least you should consider it. If you don't have one near the pole then you'll need cable limiters at the supply side connection per 705.31. I think it's better practice to have a disco within 10ft if you can. You need a disconnect at the building like you would for any other feeder.

The ground rod and main-bonding jumper stuff is pretty controversial and you should ask your AHJ. Me, I would treat it like any other situation. Disconnect at the pole should have a main bonding jumper. It needs a GEC tap only if that's how the other service disconnects are done. Disconnect at the building should have a GEC to the grounding electrode that ought to already be there for the 240V panel mentioned. BUT... your AHJ might ask for something entirely different if they think that the solar is not a service disconnect of if they just have weird ideas about solar.

 

[GoldDigger]

Your images, linked through "googleusercontent", are not visible to me. Either download the images or host them at a place that does not require a login, please.

 

[solarken]

Photos again

Photos again

Sorry about the linked photos. Here they are. There do not look to be any current limiters for any of the other services coming off the pole, and there are no disconnects at the pole side.

 

[jaggedben]

That's a bit different than what I imagined. Where are the meters? Or will the PV be metered separately?

 

[solarken]

That's a bit different than what I imagined. Where are the meters? Or will the PV be metered separately?

The meter for the Farm is on the pole behind the PVC conduit runs seen in the photo. I did not get a photo of the meter, but believe it is fed from CT's. Good point, I need to make sure the Tap is on the customer side of the CT's.