New Ground Mount Installation in San Diego

[Hillsider]

Pulling conductors through conduit

Wires are always supposed to be pulled AFTER the conduit is completely in place.
Gluing up conduit around the wires is not a code compliant installation.
AFAIK gluing conduit around a pull rope is OK. (But a rag with a string and a vacuum cleaner works fine for getting the initial string through - at least on 50' it works well, I think it'd work fine even on 120' )

If you're really worried about it, for ~$50 I'd go for 1.5" instead of 1".
I'm guestimating $50, because 12 lengths at ~$3 extra plus a little for larger fittings.

I couldn't find a specific NEC prohibition re "gluing PVC around the wires, but I'll take your word for it. Likewise, your suggestion to go to 1-1/2" PVC has merit. I am not too concerned about the added cost of the larger PVC run, as I am planning on 7 10' lengths, but boosting the remaining 50' of Liquid-tight flex conduit to 1-1/2" can get really pricey. To make the entire run in PVC would be a labor-intensive nightmare, as the last stretch has to navigate around a couple of trees, under a low block wall & under a walkway behind the house. I have never tried using string for pulling any conductors farther than 30' in 1/2" EMT, & prefer the "security" of a 50' fisch-tape. For those like Bruce, who have used cordage for pulling cables through 100'+ of conduit, is it correct to assume you initially vacuum through a light cord, tied to some light material, then progress to heavier cordage to actually yank the conductors through. Is it allowable to do a partial pull through buried PVC, then do a separate pull through un-buried LFMC ( since that type of conduit is ok both buried & exposed ), and then bury it after the pull? Just asking.

[Lpotter86]

Looks good.

[Mojave]

Can you break down (or at least estimate) the pricing? $4.65/watt. I can look up pricing on the panels, but how much for the trenching, mounting, wiring, etc.? Or was it just a quoted price for the whole system?

I'm also in San Diego and looking to do a ground mounted system but on flat ground. I'm on a canyon, but it's north facing and I have shading on my roof, and the roof itself is very new. The land has no shading except maybe mid-winter and sits empty with only ice plant.

Also, what is the total square footage of the 7x3 panel layout?

Thanks for a great and informative read.

[bcroe]

(But a rag with a string and a vacuum cleaner works fine for getting the initial string through - at
least on 50' it works well, I think it'd work fine even on 120' )

It worked at 220' here. Needed to run power out there to operate the vacuum. Bruce Roe

[foo1bar]

I am planning to lay my 5 THWN-2 conductors from the array to the inverter inside the 120' 1" PVC & LFMC conduit as I assemble it & lay it in the trench.

Wires are always supposed to be pulled AFTER the conduit is completely in place.
Gluing up conduit around the wires is not a code compliant installation.
AFAIK gluing conduit around a pull rope is OK. (But a rag with a string and a vacuum cleaner works fine for getting the initial string through - at least on 50' it works well, I think it'd work fine even on 120' )

If you're really worried about it, for ~$50 I'd go for 1.5" instead of 1".
I'm guestimating $50, because 12 lengths at ~$3 extra plus a little for larger fittings.

[lkstaack]

Unfortunately, I wasn't present when they pulled wire, so my knowledge is limited to what you see in the photos.

[Hillsider]

Conduit Run Details

To the OP ... I have referred back to your pics & narrative several times, as I proceed to fine-tune my own ground-mount plans, & I have a couple of questions regarding the conduit run from your array up to your back yard; also one regarding your array junction box. Your narrative seemed to indicate that your wire-pull operation occurred after the down-hill conduit run was covered. I am planning to lay my 5 THWN-2 conductors from the array to the inverter inside the 120' 1" PVC & LFMC conduit as I assemble it & lay it in the trench. I have pulled as many as three #12 AWG conductors through 50' if conduit with lube & fisch-tape, but would hesitate to pull 5 #8 conductors 70-80'. One of your pics showed your red, black & green conductors "emerging" from the conduit, so I assume the pull was done before the trench covering (??). In the same pic, I couldn't tell how many conductors, total, that you ran underground. Did your installer run two parallel strings + EGC back to the inverter?
The open view of your junction box did not show any obvious bus-bars, so I could not determine how your installer joined the USE-2 cables to THWN building wire conductors. I am planning on using a Wiley ACE transition box, with DIN rails, to make the junction. I believe the 2011 NEC rules allow the run to be made without an OCPD device, as long as no more than 2 parallel DC strings are run together. Comments, anyone?

GS

[Hillsider]

Top Mounting of SolarEdge Optimizers

What I've seen for optimizers they're mounted to the top of the rail (panel side of the rail) and they are parallel with the panel.
For example, at 1:05 in this video https://www.youtube.com/watch?v=wLoF9rMlmWk

The #7 photo in post #4 of this thread shows the same mounting - just viewing from below, while the video angle is shot from above the optimizer

My optimizers are mounted the same way - bolts in the top channel of the rail - using the same channel that is used for the clamps holding the panels.

BTW the bolts don't come with the rail or the optimizer - so plan on purchasing them separately. I bought those stainless-steel bolts, washers, and lock-nuts from Home-Depot.

Thanks for the installation video reference. Photo #7 viewing direction obscured the side-slot of the rail, so it didn't really show the optimizer's point of attachment. From the video it looks like the only caution to be observed for top-mounting each panel's optimizer on one of it's rail-pairs ( between the mid-clamps ) is to use a mounting bolt that does not protrude above the surface of the optimizer, farther than the distance between the bottom of the panel frame, and it's lower surface.

[foo1bar]

I have been following your installation progress with much interest, as I am putting together my drawing package & budget spreadsheet for a similar ground-mount array. I noticed on one of your photos ( #7 ) from your 3/29/15 post, that the optimizers are installed in the side-slot of the IronRidge rail, parallel to the plane of the solar panel. The product description of the P300 optimizer shows a mechanical mounting slot on the optimizer that facilitates mounting flush with the rail, but perpendicular to the panel. Did the installer use a right-angle T-bolt to attach it, or does SolarEdge offer an adapter to allow for that manner of attachment? BTW, if it is convenient, I would appreciate a PM from you, regarding your installer, as I am still on the fence about a self-install vs. contract job.

What I've seen for optimizers they're mounted to the top of the rail (panel side of the rail) and they are parallel with the panel.
For example, at 1:05 in this video https://www.youtube.com/watch?v=wLoF9rMlmWk

The #7 photo in post #4 of this thread shows the same mounting - just viewing from below, while the video angle is shot from above the optimizer

My optimizers are mounted the same way - bolts in the top channel of the rail - using the same channel that is used for the clamps holding the panels.

BTW the bolts don't come with the rail or the optimizer - so plan on purchasing them separately. I bought those stainless-steel bolts, washers, and lock-nuts from Home-Depot.

[Hillsider]

Ground-Mount Optimizer Installation

I have been following your installation progress with much interest, as I am putting together my drawing package & budget spreadsheet for a similar ground-mount array. I noticed on one of your photos ( #7 ) from your 3/29/15 post, that the optimizers are installed in the side-slot of the IronRidge rail, parallel to the plane of the solar panel. The product description of the P300 optimizer shows a mechanical mounting slot on the optimizer that facilitates mounting flush with the rail, but perpendicular to the panel. Did the installer use a right-angle T-bolt to attach it, or does SolarEdge offer an adapter to allow for that manner of attachment? BTW, if it is convenient, I would appreciate a PM from you, regarding your installer, as I am still on the fence about a self-install vs. contract job.

[lkstaack]

As for critters, Fry's sells a solar pest repeller that emits sounds that I heard works well on ridding of rats and gophers.

I'm more concerned about black widows. I'm a total baby around them.

[bcroe]

Cyclic or occasional repeated loads such as those caused by wind indicate that occasional or scheduled check of bolting is a good idea, sometimes mandated depending on application. If you can get at them, check a few every now/again and look for loosening , corrosion or other developments, see if you can spot a pattern and respond accordingly.

Sometimes lock washers help, but fasteners can always creep from variable external loadings, thermal expansion, corrosion from various sources, etc.

I choose to use Stainless Steel, a bit longer so I can put on 2 nuts. If things are expanding/
contacting/straining, a single nut might get worked loose. A lock washer helps, but may
not be enough. A pair of nuts locked together will never move, though adjustments might
still be necessary. There are also elastic nuts, I am afraid to use them in this environment.

Lessor materials than SS may become corroded in place after a while. Bruce Roe

[thejq]

They did. I would have pressed further on the nylon tie issue, but my research couldn't find the optimal way of securing cables to a round pipe. Nevertheless, I feel they could have used the proper hold-downs on the racks; I'm sure they did for yours. There will be all sorts of critters living under there when the ties ultimately fail.

When I did mine, I wasn't as knowledgeable as you're now. So I didn't even notice what type of ties they used. At least being on the ground you can check it once in a few years. Where are many ways to prevent critter living under. As for critters, Fry's sells a solar pest repeller that emits sounds that I heard works well on ridding of rats and gophers.

[J.P.M.]

One suggestion I would make as I have a ground mount(S:Flex) as well: If your panels are at a sharp angle to the ground (mine is at 35 degrees) and in potential windy environment: Ask your installer for the torque specifications for the attachments of the rails to the concrete vertical posts as well as the attachments of the panels to the rails and check 1 year after installation. My South facing panels have occasional strong winds from the North and West. After 2 years, I just happened to check a nut under the panels and found I could loosen it by hand. I subsequently Googled the torque specs for my system and surprisingly, found many of them were not up to the specified torque but none were over torqued. I called my installer about this and he did not seem surprised given the wind loads and suggested I tightened them and said usually after this first time, they will remain to spec. I'll probably check them yearly...

Cyclic or occasional repeated loads such as those caused by wind indicate that occasional or scheduled check of bolting is a good idea, sometimes mandated depending on application. If you can get at them, check a few every now/again and look for loosening , corrosion or other developments, see if you can spot a pattern and respond accordingly.

Sometimes lock washers help, but fasteners can always creep from variable external loadings, thermal expansion, corrosion from various sources, etc.

[gregvet]

They did. I would have pressed further on the nylon tie issue, but my research couldn't find the optimal way of securing cables to a round pipe. Nevertheless, I feel they could have used the proper hold-downs on the racks; I'm sure they did for yours. There will be all sorts of critters living under there when the ties ultimately fail.

One suggestion I would make as I have a ground mount(S:Flex) as well: If your panels are at a sharp angle to the ground (mine is at 35 degrees) and in potential windy environment: Ask your installer for the torque specifications for the attachments of the rails to the concrete vertical posts as well as the attachments of the panels to the rails and check 1 year after installation. My South facing panels have occasional strong winds from the North and West. After 2 years, I just happened to check a nut under the panels and found I could loosen it by hand. I subsequently Googled the torque specs for my system and surprisingly, found many of them were not up to the specified torque but none were over torqued. I called my installer about this and he did not seem surprised given the wind loads and suggested I tightened them and said usually after this first time, they will remain to spec. I'll probably check them yearly...