My first install, questions thread.

five.five-six

Senior Member
Location
california
How are you guys getting mods to the roof? I was thinking I’d rent a scissors lift but that seems rather expensive. Next thought was to buy one but then I have to store it.

Shingle hoist? Ropes?


I did read about someone putting them on a backpack but it seems that one good gust of wind and it would be curtains
 

Whalepod

Member
Location
CA
How are you guys getting mods to the roof? I was thinking I’d rent a scissors lift but that seems rather expensive. Next thought was to buy one but then I have to store it.

Shingle hoist? Ropes?


I did read about someone putting them on a backpack but it seems that one good gust of wind and it would be curtains
One story - one guy on the ground passing to 1-2 guys directly on the roof.

Two Story - find an intermediate roof and pass from the ground to the 1st story, then the 1st story to 2nd story

Two Story Cube home - if no intermediate roof lines are available I will go to home depot and buy some regular bent steel S style hooks that will pilot into the holes in the module for grounding lugs, then bend up some 8 or 6 bare copper into a tripod/coat hangar looking thing. two points on the bottom have the S hooks attached, and the top of the triangle is twisted into an eyelet that I can thread some high tensile strength rope, or some kind of mechanical clip into. The loose end of the rope stays on the roof and I use 1 or 2 staff members who stand at the head of the ladder that's already been setup and strapped to the rafter tail. drop your hook to the ground and hook it up to the module. Pull module up the ladder, preferably while you have another staff member climbing up the ladder behind the module to keep a hand on it while the roof guys pull it up.

Resi jobs (1-2 stories) I've never considered renting a scissor lift/gradall. Big resi jobs where we're humping any more than 30 mods (or a pallet of mods depending on the module manufacturer) I'll consider a gradall but probably wont pull the trigger because of the pace of our jobs. Multifamily/commercial I'll definitely run some kind of additional machinery. not only does it help with modules, but it's really helpful to be able to drop all equipment directly to the roof.
 

five.five-six

Senior Member
Location
california
One story - one guy on the ground passing to 1-2 guys directly on the roof.

Two Story - find an intermediate roof and pass from the ground to the 1st story, then the 1st story to 2nd story

Two Story Cube home - if no intermediate roof lines are available I will go to home depot and buy some regular bent steel S style hooks that will pilot into the holes in the module for grounding lugs, then bend up some 8 or 6 bare copper into a tripod/coat hangar looking thing. two points on the bottom have the S hooks attached, and the top of the triangle is twisted into an eyelet that I can thread some high tensile strength rope, or some kind of mechanical clip into. The loose end of the rope stays on the roof and I use 1 or 2 staff members who stand at the head of the ladder that's already been setup and strapped to the rafter tail. drop your hook to the ground and hook it up to the module. Pull module up the ladder, preferably while you have another staff member climbing up the ladder behind the module to keep a hand on it while the roof guys pull it up.

Resi jobs (1-2 stories) I've never considered renting a scissor lift/gradall. Big resi jobs where we're humping any more than 30 mods (or a pallet of mods depending on the module manufacturer) I'll consider a gradall but probably wont pull the trigger because of the pace of our jobs. Multifamily/commercial I'll definitely run some kind of additional machinery. not only does it help with modules, but it's really helpful to be able to drop all equipment directly to the roof.
Thank you, great info!!!

it’s 26 modules so, not quite 30 but I’m regretting doing supports on 4’, with the tile roof, it’s a lot of work.

I’m to the point that I’m removing 2-3 courses of tiles at a time, laying out the supports and laying an entire course of 30# felt at a time. With 4’ supports, It’s probably less work than flashing up each individual support and it probably adds 30+ years to the sections of roof I am working, at least that’s my hope.


With the amount of labor involved in doing tile roofs, I’m either going to have to get a whole lot faster or I just don’t see how I can make any money at it. :(
 

five.five-six

Senior Member
Location
california
3’ from gas meter?

3’ from gas meter?

So, I have a buddy in my aquarium club who has been with the local natural gas company for many years. He told that the gas meter needs to be at least 3 linear feet from any electrical equipment such as an inverter and that they may require you to relocate one or the other if the meter is too close the inverter. He also told me that the rule has been relaxed to only require a 3’ circle around the meter. Has anyone else ran into this?


Also, my 9-year-old made this inverter “unboxing” video on youtube. Do me a favor and watch it in a separate browser so he gets “views” on it. It means the world to him at this age and he is really excited about the 77 views it already has. Like and or comment for bonus points. Thanks :)

https://youtu.be/i8tscM2yuEA
 

jaggedben

Senior Member
The 3ft rule for the gas meter is in the California Mechanical Code. Technically it is 3ft from the manifold vent (the vent on that flying saucer looking piece on the utility side of the gas meter). Sometimes the vent has a hose on it leading from inside to outside (in older more urban areas), in which case I think you can argue it's from the hose outlet and not the manifold. BUT I have learned not to count on winning those arguments with an inspector. Keep all your equipment at least 3ft from all the stuff mentioned to avoid issues.

If you are involving a utility in an electrical service upgrade there may be further restrictions.
 

five.five-six

Senior Member
Location
california
If you are involving a utility in an electrical service upgrade there may be further restrictions.

Do tell!


The gas meter is right close to the service and it is being upgraded. The cold water entrance is the other side of the house sit 24’ vaulted ceilings but the gas meter is not 5’ away :(
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
So, I have a buddy in my aquarium club who has been with the local natural gas company for many years. He told that the gas meter needs to be at least 3 linear feet from any electrical equipment such as an inverter and that they may require you to relocate one or the other if the meter is too close the inverter. He also told me that the rule has been relaxed to only require a 3’ circle around the meter. Has anyone else ran into this?
In the AHJ's we service there is some variability; some say 3' measured radially and some say 3' measured linearly along the wall at any height. What they agree upon is the point from which the measurement is taken; it's the vent on the pressure relief valve adjacent to the gas meter itself.
 

pv_n00b

Senior Member
Location
CA, USA
Also, my 9-year-old made this inverter “unboxing” video on youtube. Do me a favor and watch it in a separate browser so he gets “views” on it. It means the world to him at this age and he is really excited about the 77 views it already has. Like and or comment for bonus points. Thanks :)

https://youtu.be/i8tscM2yuEA
Great video, "Who needs instructions?" He will go far.

I have to wonder how you can wear that shirt around your son though.
 

five.five-six

Senior Member
Location
california
Great video, "Who needs instructions?" He will go far.

I have to wonder how you can wear that shirt around your son though.
LMAO

I’m raising them to have thick skin.

I don’t think he has any idea what that shirt is about. I got it long before either of them were born. I can’t really wear it in public so it’s been a good “working around the house” shirt
 

inspector23

Senior Member
Location
Temecula, CA
A couple of things to keep in mind

A couple of things to keep in mind

Your son did a great job on the video. Hope he follows up with a completed project video, maybe interviewing installer/contractor:)?

A few things to keep in mind for this and future installs. ( 2017 NEC).

1. THHN cannot be used in exterior raceways (EMT) on the roof. 300.38, 310.10(C)

2. Be sure to double check your local ambient temperature and the spacing height above the roof to the bottom of the conduit you will be installing.

Chances are # 10 will not be enough ampacity, especially if you are combining strings. Table 310.15(B)(16) is only accurate for ambient temperature of 86 degrees F (see paragraph at the top of the table). You have to adjust the ampacity based upon table 310.15(B)(2)(a) for your local area.

If you do not know your local ambient temperature, a guide is available for free PDF from Copper Development Association. https://www.copper.org/applications/electrical/building/pdf/rooftop.pdf

If the bottom of the conduit is less than 7/8" off the roof, you also have to add 60 degrees F to the ambient temperature for your local area. 310.15(B)(3)(c).

And if you have more than 3 current carrying conductorsin the conduit, you have to reduce the ampacity even further per Table 310.15(B)(3)(a).

It is very common in my area for a #10 to only carry 16 amps on a roof.
 

jaggedben

Senior Member
...

A few things to keep in mind for this and future installs. ( 2017 NEC).

1. THHN cannot be used in exterior raceways (EMT) on the roof. 300.38, 310.10(C)
Hard to find THHN these days that isn't also marked THWN. I did have an issue a few years ago where my supplier slipped me some wire that wasn't marked THWN-2.


2. Be sure to double check your local ambient temperature and the spacing height above the roof to the bottom of the conduit you will be installing.

Chances are # 10 will not be enough ampacity, especially if you are combining strings. Table 310.15(B)(16) is only accurate for ambient temperature of 86 degrees F (see paragraph at the top of the table). You have to adjust the ampacity based upon table 310.15(B)(2)(a) for your local area.

If you do not know your local ambient temperature, a guide is available for free PDF from Copper Development Association. https://www.copper.org/applications/electrical/building/pdf/rooftop.pdf

If the bottom of the conduit is less than 7/8" off the roof, you also have to add 60 degrees F to the ambient temperature for your local area. 310.15(B)(3)(c).

And if you have more than 3 current carrying conductorsin the conduit, you have to reduce the ampacity even further per Table 310.15(B)(3)(a).

It is very common in my area for a #10 to only carry 16 amps on a roof.
#10 is usually fine for up to three Solaredge strings unless the design temperature used is very high. I suppose where I am in northern California this may be more true than in the southern parts. In any case, these strings are typically not combined on the roof and only have a circuit current of 15A.

The 7/8" remark is not correct under the 2014 NEC. The adder is 40F for .5" to 3.5." We've got 5 months to go now until the code changes in California. :D
 

five.five-six

Senior Member
Location
california
Your son did a great job on the video. Hope he follows up with a completed project video, maybe interviewing installer/contractor:)?

A few things to keep in mind for this and future installs. ( 2017 NEC).

1. THHN cannot be used in exterior raceways (EMT) on the roof. 300.38, 310.10(C)

2. Be sure to double check your local ambient temperature and the spacing height above the roof to the bottom of the conduit you will be installing.

Chances are # 10 will not be enough ampacity, especially if you are combining strings. Table 310.15(B)(16) is only accurate for ambient temperature of 86 degrees F (see paragraph at the top of the table). You have to adjust the ampacity based upon table 310.15(B)(2)(a) for your local area.

If you do not know your local ambient temperature, a guide is available for free PDF from Copper Development Association. https://www.copper.org/applications/electrical/building/pdf/rooftop.pdf

If the bottom of the conduit is less than 7/8" off the roof, you also have to add 60 degrees F to the ambient temperature for your local area. 310.15(B)(3)(c).

And if you have more than 3 current carrying conductorsin the conduit, you have to reduce the ampacity even further per Table 310.15(B)(3)(a).

It is very common in my area for a #10 to only carry 16 amps on a roof.

I’m running 2 sets of #10’s back to the inverter and a #8 EGC bond.

My understanding is the #8 needs to be contagious to the Jbox on the roof where I land it on a ground buss and then bond the rails to that buss

Just to be clear, #10 THHN/THWN will be ok from the j-box to the inverter even if some of it is in EMT on the roof?

My tubeing is 4” off the roof and my area would be Ontario california.
 

jaggedben

Senior Member
Wiring in EMT is fine as long as it is wet rated, i.e. of a type with a 'W' in it.

To use #10 on the roof for Solaredge strings it will need to be 90C wire, i.e. with '-2' at the end.

Thus THWN-2. Most suppliers will give that to you by default but double check.

Now for the size...

Your SolarEdge string is max 15A which is 18.75 at 125% continuous.
90C wire is rated 40A which with 4-6 conductors is 32A at 80%.
18.75/32 is .58 so that's the minimum temperature derating factor you can use. Works for me almost all the time but Ontario may get hotter than where we work. Depends on your AHJs feelings about the ambient temp you use.
 

five.five-six

Senior Member
Location
california
Wiring in EMT is fine as long as it is wet rated, i.e. of a type with a 'W' in it.

To use #10 on the roof for Solaredge strings it will need to be 90C wire, i.e. with '-2' at the end.

Thus THWN-2. Most suppliers will give that to you by default but double check.

Now for the size...

Your SolarEdge string is max 15A which is 18.75 at 125% continuous.
90C wire is rated 40A which with 4-6 conductors is 32A at 80%.
18.75/32 is .58 so that's the minimum temperature derating factor you can use. Works for me almost all the time but Ontario may get hotter than where we work. Depends on your AHJs feelings about the ambient temp you use.
Oddly enough about 1/2 of my #10 isn’t THWN-2. I do have several red and several black but I was hoping to make each string a different color. Not a huge problem though.

This is a problem. I did take all the SolarEdge online courses and read everything I could find but I don’t recall anything saying to take down the optimizers serial numbers.... until I unboxed the inverter.... which was after I installed the modules. Is there a good way to identify the optimizers without removing the modules now?


And here’s our latest “unboxing” video. Thanks for all the views, comments and likes. They made my son’s day :)


https://youtu.be/lxV4DzAOvoM
 

jaggedben

Senior Member
Depending on the rail you used, it may be possible to stick a cell phone under the array and get pics of some of the optimizer serial numbers on the bottom of the mounting bracket. That is for optimizers mounted near enough to the edge of the array.

Otherwise, you can just fake your way through the array map and as long as you are the one doing any servicing it won't really matter. Later on if/when you have to pull up panels to find a bad optimizer you can take that opportunity to correct relevant portions of the map.

Don't ask me how I know these things. :slaphead:
 

five.five-six

Senior Member
Location
california
Depending on the rail you used, it may be possible to stick a cell phone under the array and get pics of some of the optimizer serial numbers on the bottom of the mounting bracket. That is for optimizers mounted near enough to the edge of the array.

Otherwise, you can just fake your way through the array map and as long as you are the one doing any servicing it won't really matter. Later on if/when you have to pull up panels to find a bad optimizer you can take that opportunity to correct relevant portions of the map.

Don't ask me how I know these things. :slaphead:

I was thinking I could just set a tarp over each mod one at a time to identify which is which...


I think the way I installed them, the serial number is right against the rail

I’ll have to check next time I’m up there but I think if the ser is exposed, I could get them all with a “selfie stick” LOL
 
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