My solar system

tortuga

Senior Member
Location
(44.057116, -123.103394)
Occupation
field supervisor
How abou that transformer picture - ever seen a #10 coming out of a load break elbow? ;) Thats 2KV Pv wire, transformer is 2400, tapped down all the way to 2280, close enough. I was too cheap to buy custom transformers. Runs about 500 feet to where it Tees into another 1900 foot line which goes from the service pedestal and transformer to the house.

Its good to be an electrician sometimes.
Very cool install thanks for posting, I have contemplated doing the exact same thing many times over the years.
Especially a step up to step down HV system on rural property. I have looked into a 1.5kV transformers and the PV wire before.
How did you make up the stress cones? Did you actually find ones that fit?
We run 7.2 kV underground once in a while but the local utility always makes up the stress cones. I know they have gotten easier but they can be a point of failure.
 
Very cool install thanks for posting, I have contemplated doing the exact same thing many times over the years.
Especially a step up to step down HV system on rural property. I have looked into a 1.5kV transformers and the PV wire before.
How did you make up the stress cones? Did you actually find ones that fit?
We run 7.2 kV underground once in a while but the local utility always makes up the stress cones. I know they have gotten easier but they can be a point of failure.
I dont think you will find a load break connector that fits such small wire. Note 310.106(A) requires minimum conductor size of #8 for 2001-5000V so that is likely why. There are two things to match up: the crimp on connector and the opening on the tail of the elbow body. Without looking real hard, I only found connectors go down to #4, but they must be available down to #8 as MV-90 #8 is a thing. The connector is a snug fit into the body of the elbow so I didnt want to deform it too much by crimping it. I guess I could have packed some more strands in there to tighten it up, but I ended up soldering it instead. The opening in the elbow only goes down to about .5 inch, but since the PV wire isnt shielded, I dont see it as being important that the cable sheath interfaces snugly with the semi-con of the elbow.

Over 2.4KV, I would want to use shielded cables and all the correct stuff, but for <2.4, IMO its not very critical.
 

tortuga

Senior Member
Location
(44.057116, -123.103394)
Occupation
field supervisor
I dont think you will find a load break connector that fits such small wire. Note 310.106(A) requires minimum conductor size of #8 for 2001-5000V so that is likely why. There are two things to match up: the crimp on connector and the opening on the tail of the elbow body. Without looking real hard, I only found connectors go down to #4, but they must be available down to #8 as MV-90 #8 is a thing. The connector is a snug fit into the body of the elbow so I didnt want to deform it too much by crimping it. I guess I could have packed some more strands in there to tighten it up, but I ended up soldering it instead. The opening in the elbow only goes down to about .5 inch, but since the PV wire isnt shielded, I dont see it as being important that the cable sheath interfaces snugly with the semi-con of the elbow.

Over 2.4KV, I would want to use shielded cables and all the correct stuff, but for <2.4, IMO its not very critical.
Gotchya, so strees-scones and the loadbreak elbows are only needed for over 2.4kV? Thats good to know. My working experience doing terminations tapers off around 600 Volts.
So you have 3 privately owned transformers on your property; your utility serves you regular 120/240 single phase and you have a step up transformer to 2.2kV there to feed your 1900 foot line with a transformer on the other end for your house, and you have teed into this line?
 
Gotchya, so strees-scones and the loadbreak elbows are only needed for over 2.4kV? Thats good to know. My working experience doing terminations tapers off around 600 Volts.
It is generally accepted that you do not need shielded cables at or below 2.4KV. A few code cycles ago they did restrict non shielded cables from 4160 which was allowed, but it is still allowed for 2.4KV. I just used an elbow because that is how to interface with the pad transformer bushing. One of my transformers is a dry type and has regular mechanical lugs.


So you have 3 privately owned transformers on your property; your utility serves you regular 120/240 single phase and you have a step up transformer to 2.2kV there to feed your 1900 foot line with a transformer on the other end for your house, and you have teed into this line?
Yes. Actually the transformer at the house has two primary bushings ("loop feed") so the MV loops thru and goes to the solar. At first I was going to run 120/240 down there, but I realized the solar is getting stepped up anyway, so I might as continue the 2.2Kv down there and add another transformer since either way would be the same transformer load losses. OF course the third tranny does at no load losses but the the wire savings make it worth it.

IF I was going to do this for someone professionally, I would either get 2 KV transformers, or if you want to stick with regular 2.4KV, you could get 5KV airport lighting cable which is very affordable. Its very similar to the PV wire, just a little thicker.
 

tortuga

Senior Member
Location
(44.057116, -123.103394)
Occupation
field supervisor
It is generally accepted that you do not need shielded cables at or below 2.4KV. A few code cycles ago they did restrict non shielded cables from 4160 which was allowed, but it is still allowed for 2.4KV. I just used an elbow because that is how to interface with the pad transformer bushing. One of my transformers is a dry type and has regular mechanical lugs.




Yes. Actually the transformer at the house has two primary bushings ("loop feed") so the MV loops thru and goes to the solar. At first I was going to run 120/240 down there, but I realized the solar is getting stepped up anyway, so I might as continue the 2.2Kv down there and add another transformer since either way would be the same transformer load losses. OF course the third tranny does at no load losses but the the wire savings make it worth it.

IF I was going to do this for someone professionally, I would either get 2 KV transformers, or if you want to stick with regular 2.4KV, you could get 5KV airport lighting cable which is very affordable. Its very similar to the PV wire, just a little thicker.
Wow, When can we all book a tour? :)
 

peter d

Senior Member
Location
New England
How was it to pull that 2 Kv PV wire through 1900 feet of 3/4" PVC? It looks silicone insulated so seems like a massive amount of friction for that distance. :blink:
 
How was it to pull that 2 Kv PV wire through 1900 feet of 3/4" PVC? It looks silicone insulated so seems like a massive amount of friction for that distance. :blink:
I pulled out the wire then sleeved it in 50 foot sections (Yet another code violation). Its a long walk but gets 50 feet shorter every time. Yes many MV cables are EPR rubber, but PV wire is usually just RHW-2 but it is still not great to pull. We did a bunch of 400 ish foot pulls of 8 #8's of the 2KV PV wire on a commercial PV job. It sucked, I was dreaming of SimPull.
 
UPDATE

UPDATE

So we had some rain the other day and it was the first time I was around so I go down to see how my system is doing. Water EVERYWHERE! My first though is ok this idea was a total failure, but on closer examination, I dont think it is too bad. Turns out its that pesky surface tension (I think actually the correct words are adhesion and cohesion). Water drips out of the flashing and travels on the underside of it until it JUST clears the gutter by like 3/4 of an inch :rant: and then drips down. I didnt have my phone to get an action shot, so see the picture with the gutter removed and the two black sharpie marks. Those are about how far the water would travel out before dripping. It seems like this was happening to about half of them. I played around to figure out what was required to break the surface tension and it doesnt take much. Even a little piece of down turned metal sitting in the flashing kills it. Just to be safe though, I screwed and caulked on a double ridged piece and put a bead of caulk after that as a redundancy (see picture). I am now awaiting for rain to look for leaks. Another option is just to make the gutters double width (with a piece of edge guard over the seam) which would definitely catch everything, even without the surface tension breakers, but I wanted to put the breakers on anyway so Ill see how that goes.

Its weird stuff: At first I tried messing around in the sink with a piece of flashing to see what I needed to do, but I COULD NOT get it to happen even with the same piece of flashing. Must be chemistry difference between the tap water and the rain water.
 

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tortuga

Senior Member
Location
(44.057116, -123.103394)
Occupation
field supervisor
Hey @electrofelon how is your 2kV feeder is doing?
I am contemplating doing something like this for two rural water pumping projects with long feeders (1000').
I would need to keep it code compliant though.
Did you ever find a source for a 2kv transformer?
Cheers
 
Hey @electrofelon how is your 2kV feeder is doing?
I am contemplating doing something like this for two rural water pumping projects with long feeders (1000').
I would need to keep it code compliant though.
Did you ever find a source for a 2kv transformer?
Cheers
Hey Tortuga, I do have some good information for you. I was investigating a 4000' step up step down scheme for someone else and I wanted it to be code compliant also, so I looked into some other options.

First of all, yes my setup is working awesome. Love it. Feel like I really got my moneys worth out of that 2KV PV wire making it work so hard :LOL:

I got a few quotes for 15 KV transformers. One place quoted me ermcos for $1825, another was eaton for $2500. Now these were both standard 2400 voltage, but it sounded like the eaton ones were built to order, so perhaps the price for a 2KV is the same/similar.

Another thing I looked at was CIC cable assemblies. These were from southwire and will give you an idea on cost. Comes installed in 1 inch black schedule 40 pipe.


About 4000 feet CIC:

option #1: 2 - #10 AWG 2KV PV wire/RHH-2, and one #8 white THHN. $1.44 per ft
option #2: 2 - #8 AWG 2KV PV wire/RHH-2, and one #8 white THHN.
option #3: 2 - #8 5KV unshieled L-824 (airport lighting cable), and one #8 white THHN. $1.83 per ft

Note these have two ungrounded conductors because this job had two separately metered circuits. Option #2 did not come back with a price, I dont know why. There are still some potential code issues with these: Note that #8 is the minimum size for 2001-5000 volts. 0-2000V can be #14. The L-824 easily has the voltage rating for full 2400, but unshieded cables above 2000V have limited allowed use. All this really probably makes it worth staying with 2KV if full code compliance is needed.

A final option may be just to go with 15KV concentric neutral cable. Its only 2 bucks a foot for #2 AL. I would try to get it in CIC.
 
One more thing: The big problem with going the 2KV PV wire route if you are going totally on the books is you are then pigeon holed into 300.50(A)(3) which requires RMC, IMC, or RNC encased in concrete. That could easily make it a deal breaker and make CN cable the preferred method. Perhaps it would be worth investigating a custom run of coated MC which then would put you under 300.50(A)(1). Although if you go IMC, you then only need to be 6" deep, which, in my situation, was a necessity due to that mini trencher, going thru the woods, not wanting to cut trees and make a mess, etc. For me, even if I had to get it inspected and use IMC, it would have been worth it. Depending on the load, we are are only talking two #12 or #10's so 1/2 or 3/4 would be all that is required.
 
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