hitehm
Senior Member
- Location
- Las Vegas NV
Happy Holidays all.
We are installing solar on our first working farm so I naturally have some questions and concerns. Fyi, we are still on NEC 2017.
The Basics: We are installing a 20 panel array on 4 separate “bays”. See the attached pic. Each bay is an aluminum/galvanized steel framed structure with corrugated roof. Each bay has 8 horse stalls. There is 12 ft of ground space separating each bay so they are technically 4 separate structures. We’ll be using a single 4” roof-to-roof cable tray to span our conduit between structures. There will be a 150’ trench from the closest bay to the MSP and service equipment. The inverter/batteries are two Tesla PW3s.
Questions:
1: 690.47 - Grounding Electrode System. (A) Buildings or Structures Supporting a PV Array. A building or structure supporting a PV array shall have a grounding electrode system installed in accordance with Part III of Article 250.
Seems pretty clear were gonna have to do an Electrode system for all 4 bays, which will almost definitely be ground rods. The question is, do we need 2 at each structure 6’ apart, or can we do 1 at each bay and tie them together or is there a better way to do this entirely?
2: Originally we were gonna build and mount the PW3s on a Unistrut frame at the first bay and then trench the inverter AC to the service eq. However, due to several issues (dust, mud, animals, traffic, limited space, etc) it was decided to run the 8 DC strings in the trench from the array area to the service eq. My question is just pros and cons of doing this. Any input is appreciated on long AC vs DC wire runs. The AC would’ve been less wiring but more work and more challenges with the inverters and disconnects at the bays. FYI, we’re ok on Vdrop and Tesla max distance for DC strings.
3: Article 547 Agricultural Buildings - Other than making sure all equip. near the bays is rated for dust protection, any other concerns we should be aware of? Equipotential Planes perhaps?
That’s it for now but any other opinions, input, concerns etc. please add to comments. Fyi, the pic is taking at bay 1 looking down the center corridor between all 4 bays.
We are installing solar on our first working farm so I naturally have some questions and concerns. Fyi, we are still on NEC 2017.
The Basics: We are installing a 20 panel array on 4 separate “bays”. See the attached pic. Each bay is an aluminum/galvanized steel framed structure with corrugated roof. Each bay has 8 horse stalls. There is 12 ft of ground space separating each bay so they are technically 4 separate structures. We’ll be using a single 4” roof-to-roof cable tray to span our conduit between structures. There will be a 150’ trench from the closest bay to the MSP and service equipment. The inverter/batteries are two Tesla PW3s.
Questions:
1: 690.47 - Grounding Electrode System. (A) Buildings or Structures Supporting a PV Array. A building or structure supporting a PV array shall have a grounding electrode system installed in accordance with Part III of Article 250.
Seems pretty clear were gonna have to do an Electrode system for all 4 bays, which will almost definitely be ground rods. The question is, do we need 2 at each structure 6’ apart, or can we do 1 at each bay and tie them together or is there a better way to do this entirely?
2: Originally we were gonna build and mount the PW3s on a Unistrut frame at the first bay and then trench the inverter AC to the service eq. However, due to several issues (dust, mud, animals, traffic, limited space, etc) it was decided to run the 8 DC strings in the trench from the array area to the service eq. My question is just pros and cons of doing this. Any input is appreciated on long AC vs DC wire runs. The AC would’ve been less wiring but more work and more challenges with the inverters and disconnects at the bays. FYI, we’re ok on Vdrop and Tesla max distance for DC strings.
3: Article 547 Agricultural Buildings - Other than making sure all equip. near the bays is rated for dust protection, any other concerns we should be aware of? Equipotential Planes perhaps?
That’s it for now but any other opinions, input, concerns etc. please add to comments. Fyi, the pic is taking at bay 1 looking down the center corridor between all 4 bays.