Newbie here doing a 20.8kW DYI install (80 sunMAX 260W panels with microinverters)

[pclausen]

Got the footer dug along with the 6 24" holes. Footer is 24" wide and between 24" and 36" deep. The 24" holes are about 5' deep (the max my post hole digger will do). Frost line is 18" in my area, so no worries there. I have calculated I need about 14 yards of concrete.







Getting that North cross-pipe exactly located and level was a pain. But it is in place now and within 1/32" in all directions.

I picked up 50 sticks of 1/2" rebar, which I plan to put down once I get the Ironridge frame all hung.

[pclausen]

Completed the rest of the framing today, along with tying in the rebar.







Calling in an order of 14 yards Monday morning. Hopefully they will be able to come out that afternoon.

[Mike90250]

if you can bond some of that rebar to the mount posts, you will have a good Ufer ground system, if the lightning rod ( that metal building next and above the array) fails !

[tyab]

Be aware that some jurisdictions want to inspect before pouring - just make sure first before you pour.

Is that black gas pipe? I have not seen any ground systems using black pipe but schedule 40 is schedule 40 from a structure point of view.

I would also recommend tying that rebar to the vertical pipe even if you don't use it as a ufer. Check out 250.52(A)(3) for the details. If you are not putting a subpanel out there odds are your AHJ will not apply 250.52/53 to you and you only need to consider 690.47(D). If you are putting circuit breakers out there then your run becomes a feeder and then 250.52/53 do apply. And to be honest, it might simply be easier to just pound in 2 rods and call that your GE even if you have the ufer from an inspection point of view even if you do run a #4 to the rebar. In any case I would at least bond the rebar to the pipe -its there so bond it.

Looks good - you are moving right along.

[pclausen]

I was under the impression that 690.47(D) is going to be removed in the future. Some have nicknamed it 690.47(D)anger as it provides a path for lightning to travel through equipment.



Above illustration is from the following Mike Holt presentation:

https://www.youtube.com/watch?v=YuDqXFvRv94

I don't plan to install circuit breakers at the ground mount system, rather I'll run the string end runs into the same sub-panel the roof mounted strings are. I was planning to run a #6 from the Ironridge grounding lug to the ground rod at the shop building.

That said, I will go ahead and add a #4 to the rebar and run it up one of the mount post to give me the option to tie it into the Ironridge grounding lug if you guys can convince me I should.

When the AHJ came out and gave me a thumbs up on the roof panel install, I told him my plan for ground mounting the remaining 24 panels in the fill dirt area, and he was good with my plan to dig 2' footers and said they did not need to come out and inspect before pouring. We did not discuss grounding of the ground mount system, but I will call them to get their opinion. By having that #4 sticking up out of the concrete, I'm leaving my options open to whatever direction the AHJ would like me to take.

[pclausen]

I got the #4 added to the rebar structure.

[Mike90250]

You need to fish the REBAR up out of the concrete. Copper will rot right off in concrete. Make the connection above the concrete.

[Guest]

Never seen copper in concrete rot off but then I live in average 20 C all year so no experience with snow . Perhaps its a cold thing?

Thats a hellova lot of work for 4 support poles . My method would be square Gal tube 3 x 3 with a cross piece of 1/4 reo welded on into holes and concrete in smaller hole 12 inches would be enough. 1/4 rod will lift 2 ton so its enough. When its gone off cut the tops off at your angle and weld on top frame. Done in a tenth of the time . Reo formwork below ground there is just silly in my opinion.Probably some beaurocratic requirement over there but jeesh ! All that concrete and reo and time and MONEY .

I live in a cyclone prone area and have lived through about 5 bad ones and my method is good for satellite mounts , clothes lines, house stumps, shed uprights , you name it. On house stumps we pump it in because its easier to do so in that hectic environment and vibrate it in . No dry mix rubbish which does work but not for this stuff.

When you backfill I would throw some bare copper wire in the trenches . It will add to security if connected to your earth and you may know already connecting it to the earth of your radio TV , HF Transmitter , satellite dish etc increases the ground plane and gives you louder and louder signals the more ground radials you have.

Just as a side note also could the pictures be put in as small ? Would that work. When I want to look I click on them and expand them.
Reason being in other countries we often don't have the download capacity you guys seem to enjoy . It costs me $50 a month for 6 Gigabytes so when you put full size pictures in we have a compulsory expensive download . We don't get a choice.

So smaller would help others. Its a discussion forum Yeh?

[foo1bar]

Never seen copper in concrete rot off but then I live in average 20 C all year so no experience with snow . Perhaps its a cold thing?

Bare copper embedded into concrete as a ufer is allowed.
It has to be at least 4AWG and at least 20' long.
I'm not sure that this connection is up to code. Is that connector isn't rated for being embedded in concrete? It probably isn't.
If there's 20' of bare 4AWG copper before the wire comes out of the concrete then it's probably fine.
If you can't do that, then a piece of rebar that sticks out of the concrete is an easy/typical solution. (and probably cheaper than 20' of copper)

Thats a hellova lot of work for 4 support poles .

6 vertical poles.
I think he's gone overboard on the concrete work... I'd think splitting it into two arrays, each with 4 posts would allow you to do just plain holes and have similar risk reduction of modules being damaged.
But it's his money. Hopefully he's got a good deal on all the rebar and the concrete.

One of the pictures shows what looks like could be the top of a white PVC pipe.
Hopefully it's not - it's some rock or something - something that wont' be a problem to put concrete directly on top of.

[pclausen]

I'll pull the #4 copper out and tie in a piece of rebar and have it exit the footer by one of the poles.

I used 39 sticks of 1/2 rebar I got for $3.50 a pop. So $135 give or take. That's less than the cost of a single panel, so I figured it would be worth it. Digging the trench didn't cost me anything since I have a backhoe at my disposal. The 11.25 yards of concrete will be pretty expensive on the other hand, but given the very loose fill dirt, I'd rather play it safe. Most of the dirt was only just leveled a few days ago and is very dry and fluffy (have not had any rain for going on 4 weeks now).

That is a 4" schedule 40 pipe in that one picture. It is just a downspout extension. I wasn't aware that would be a concern? I have another 4" schedule 40 downspout extension at the house that is fully encased in concrete. It has not been an issue for the last 15 years.

As for the pic size, I link to images at my own web site. They are reduced from their original size of 1920x1400 to whatever this forum makes them. Looks to be about 1024x768 or something similar to that. If there's a way to have smaller thumbnails and then clicking on them to get the original size, I'd be happy to do so. Not sure if that is supported here?

[foo1bar]

That is a 4" schedule 40 pipe in that one picture. It is just a downspout extension. I wasn't aware that would be a concern?

I'd be a little concerned that it'll be cracked/crushed.
You're expecting some parts to settle more than others.
So I'd be concerned that some parts under the pipe won't settle as much as the concrete structure you're making.
And you'll wind up with a lot of pressure on the top of that PVC pipe. Possibly enough to crack it or (more likely I think) crack a nearby fitting

If it's just downspout extension, a little crack won't hurt - you won't have tree roots nearby that'll find the crack and clog up the pipe.
And if it stops functioning in a few years you have equipment to dig in a new one that goes around rather than under the array.

It's probably not a problem - 4" PVC is fairly large - so if you lose some cross section it'll still carry a lot of water. And PVC will flex a fair amount.
And it's not like this is a water supply line where a crack means you suddenly have a mini swamp..

[tyab]

In the 2017 NEC 690.47(D) was renumbered to 690.47(B) and is now optional - Mike Holt was instrumental in getting it to be optional. But if you are under 2014 code - then you need it. 690.47(D) can be dangerous for solar on the roof of your home for all the reasons Mike gave in his videos on the subject. That said - for most ground mounts - you already have multiple contact points with ground - in your case you have 6 grounds (pipes in cement that are themselves not a valid GEC) plus your ufer that you just made (which is a valid GEC) plus whatever you use for the 690.47(D). Single point ground is basically impossible for this style of ground mount. So during a lightning event you may have multiple different ground potentials during the duration of that event. So unless you are willing to go to the expense of following NFPA 780, just bond all that as best as you can following 250.52/53 and 690.47(D) and the odds are it will never be part of a lightning event.

[foo1bar]

It's probably not a problem - 4" PVC is fairly large - so if you lose some cross section it'll still carry a lot of water. And PVC will flex a fair amount.

After thinking about it - I'd probably put an inch or two of sand above that pipe.
It looks like there's plenty of space to the first layer of rebar, so I don't think your rebar would be too close to the bottom.
And it wouldn't take a lot of sand.

[pclausen]

Good call, that's exactly what I ended up doing.

Pour is done.



It took just under 12 yards total. I have a piece of rebar tied in with the rest of the structure sticking out of the concrete by the South center pole.

The rep from the POCO came out today as well and signed off, even though those last 24 panels obviously aren't online yet. I'll see my first net metering bill in December.

[pclausen]

According to the Ironridge installation manual, only a single grounding lug is needed on one of my 12 aluminum rails as the panels themselves create the bond between the rails. Yet the online configurator had me order one lug per rail. Which is right?

[emartin00]

You should need 1 lug per pair of rails. The clamps will ground the modules to each pair of rails they are attached to, then you will need to ground each row to the steel piping.