New Ground Mount Installation in San Diego

[bcroe]

Bruce, It looks like we've pretty much hijacked this thread

Eventually Phase III will be east facing ground mounted and if needed Phase IV west facing ground
mounted. I have to recover a bit from Phase II before doing any more. Jeff

Yea, hijacked, don't know how to change that. I'll be watching for your east & west facing, to
compare to mine. If they are strings, one smaller inverter should handle both. That also
presents a lower total (peak) output to the PoCo, IV will add nothing. Bruce

[JFinch57]

My estimate is you are running 35,000 to 45,000 KWH a year, so about a 30 KW PV system would
handle that in the SW desert. I'm wondering how much things are degraded by clouds in MD, do
you have a handle on that now? Here there are extra strings of panels to raise cloudy output; they
are facing the rising and setting sun, so under good sun they deliver their peak power at a different
time than the south array. Overall this about matches a desert sky output. This is actually fairly
economical since inverters and everything downstream don't need to increase in size, but that is
only true with a simple string system.

And then there is the snow. One approach is do well enough in 9 months to write off the snow
months. Not happening here; most snow at night was cleared at dawn. That can become a
time consuming project with a large system, and you may also need to bring equipment to move
the piles of snow if they become high enough to block the panels. Guess you have experience at
work on this scale, how did that go? My conclusion is all panels will be set near or at vertical for
the snow season, but that will take rework here. I also plan to mount panels landscape with a gap,
so snow will only slide 39" and off, instead of 63" and onto another panel. Bruce Roe

Bruce, It looks like we've pretty much hijacked this thread while awaiting the final pictures! The 38KW AC rating was based on maxing out the conduit for load and then deciding if I was wasting money or possibly with the pool addition we would need that much. I went with the latter, bit the bullet, and put in the 3/0. (I was waiting for the electrical inspector to question the #4 neutral but he never did. Annotated it on the line diagram as balanced generation and neutral needed for Enphase Envoy communications only. Could have used something even smaller if it fit the lug). It would be a real bear to change it down the road and the savings about $100-150 to go with 2/0. I was able to deal with the snow on the ground mounted system, only loosing a couple days production. The roof mount will be a different story, even at a fairly low pitch doubt I'll be going up there with snow. The Phase II roof panels will be battling about 20-30% shade unless I can convince my wife to top the trees and I don't see that happening. Should be complete in about 1 month. Eventually Phase III will be east facing ground mounted and if needed Phase IV west facing ground mounted. I have to recover a bit from Phase II before doing any more. Here's a picture of the 3/0 feed connecting to the 400A generator transfer switch. The two white wires through the knockout are for the Envoy receptacle and go back to the outside load center. I tagged one as black (didn't have any black on hand). Jeff200A Feed.jpg

[bcroe]

Like most states they base it on your usage, and we were approved for the additional ~10KW. I don't see any reason why they wouldn't give us at least a total of 30KW. The house is 100% electric, 6,500 sq ft with 9 tons of geothermal and one of the old 5 ton heat pumps is going in the garage soon. Pumping heat to the basement to keep my mother-in-law warm has been a major contributor to the consumption! Eventually we want to add a pool and I would use solar heat collectors backed up with a Waterfurnace heat pump. That would definitely allow us to max out the 38KW. Here's the historical usage and the 10.8KW of solar was turned on July 2014 (partially in June):[ATTACH=CONFIG]6684[/ATTACH]

My estimate is you are running 35,000 to 45,000 KWH a year, so about a 30 KW PV system would
handle that in the SW desert. I'm wondering how much things are degraded by clouds in MD, do
you have a handle on that now? Here there are extra strings of panels to raise cloudy output; they
are facing the rising and setting sun, so under good sun they deliver their peak power at a different
time than the south array. Overall this about matches a desert sky output. This is actually fairly
economical since inverters and everything downstream don't need to increase in size, but that is
only true with a simple string system.

And then there is the snow. One approach is do well enough in 9 months to write off the snow
months. Not happening here; most snow at night was cleared at dawn. That can become a
time consuming project with a large system, and you may also need to bring equipment to move
the piles of snow if they become high enough to block the panels. Guess you have experience at
work on this scale, how did that go? My conclusion is all panels will be set near or at vertical for
the snow season, but that will take rework here. I also plan to mount panels landscape with a gap,
so snow will only slide 39" and off, instead of 63" and onto another panel. Bruce Roe

[SunEagle]

Like most states they base it on your usage, and we were approved for the additional ~10KW. I don't see any reason why they wouldn't give us at least a total of 30KW. The house is 100% electric, 6,500 sq ft with 9 tons of geothermal and one of the old 5 ton heat pumps is going in the garage soon. Pumping heat to the basement to keep my mother-in-law warm has been a major contributor to the consumption! Eventually we want to add a pool and I would use solar heat collectors backed up with a Waterfurnace heat pump. That would definitely allow us to max out the 38KW. Here's the historical usage and the 10.8KW of solar was turned on July 2014 (partially in June):[ATTACH=CONFIG]6684[/ATTACH]

That makes sense to me. Glad they allowed you to increase your system. Thanks for the data.

[JFinch57]

Do you have some type of agreement with your POCO that allows you to install a 38kw system?

Like most states they base it on your usage, and we were approved for the additional ~10KW. I don't see any reason why they wouldn't give us at least a total of 30KW. The house is 100% electric, 6,500 sq ft with 9 tons of geothermal and one of the old 5 ton heat pumps is going in the garage soon. Pumping heat to the basement to keep my mother-in-law warm has been a major contributor to the consumption! Eventually we want to add a pool and I would use solar heat collectors backed up with a Waterfurnace heat pump. That would definitely allow us to max out the 38KW. Here's the historical usage and the 10.8KW of solar was turned on July 2014 (partially in June):Delmarva KWh.JPG

[SunEagle]

Bruce, Yes, ~$900 worth from what I remember. Currently installing Phase II, 9.4KW on the roof and it's getting trenched back to the 10.8KW ground mount. Phase III will eventually most likely be another ground mount. The 38KW is a continuous rating on the AC side so DC will be substantially more if I expand to 100%. I could also split it with dual production meters with the other for wind. Leaving my options open at this point. Jeff.

Do you have some type of agreement with your POCO that allows you to install a 38kw system?

[JFinch57]

That is a lot of copper. Be sure to show us the 38KW version. Bruce Roe

Bruce, Yes, ~$900 worth from what I remember. Currently installing Phase II, 9.4KW on the roof and it's getting trenched back to the 10.8KW ground mount. Phase III will eventually most likely be another ground mount. The 38KW is a continuous rating on the AC side so DC will be substantially more if I expand to 100%. I could also split it with dual production meters with the other for wind. Leaving my options open at this point. Jeff.

[bcroe]

I pulled 2 #3/0 for load, 1 #4 for neutral & 1 #6 for ground through 100+' of 1 1/2" schedule 40 PVC with 2-90s and 1-45 degree bend, 270 degrees total and it meets fill requirements. Pre-lubed the PVC with a rag and plenty of synthetic lube and it went like butter.

AC is coming back to the panel. The 3/0 will handle 38KW continuous for future expansion.

That is a lot of copper. Be sure to show us the 38KW version. Bruce Roe

[JFinch57]

As I recall, we pulled 4 #6 and a #8 through 220' of pretty much straight 1.5" PVC with
plenty of wire hanging out the ends. I would hate to try pulling that around even one
right angle. All that was underground, then an angle and 2 foot riser were glued on to
the ends to bring it out of the ground to a box. Bruce Roe

I pulled 2 #3/0 for load, 1 #4 for neutral & 1 #6 for ground through 100+' of 1 1/2" schedule 40 PVC with 2-90s and 1-45 degree bend, 270 degrees total and it meets fill requirements. Pre-lubed the PVC with a rag and plenty of synthetic lube and it went like butter. Note that the neutral bypasses the meter pan/shutoff and goes straight to the load center. The friend that helped me was negative from the start, kept saying "where are we digging the new trench". After it worked he said that he'll never question anything that I do again. Sure, if I did it again it would be 2", but I originally put the conduit in the same trench over a year earlier during the backfill of geothermal lines. My thoughts back then were to have the panel inside my house and connect by all #10s, but then I realized the disconnect and outside production meter requirements. It's an Enphase system, so AC is coming back to the panel. The 3/0 will handle 38KW continuous for future expansion. Elect panels.jpg

[Hillsider]

Conduit Wire pulls

All recent posts have merit, regarding my particular situation. My plan calls for four 45 degree bends in the PVC, due to the terracing of my hillside. The final terrace above the house is where the LFMC would be joined to the PVC. If necessary, I could install a riser and junction box to satisfy the bend restriction, but I believe that would violate the rule allowing the entire DC run from the optimizers through the ACE transition box to the inverter to be considered as an inverter input circuit. Regarding pull lubrication, I checked costs, & Southwire's SimPull wire only cost $.02/ft. more than their standard THWN-2 wire. I had, at one time, considered using UF-B direct burial cable, but it only comes in 2-conductor +ground & 3-conductor + ground configurations ( not a show-stopper, but I only need four #8 DC conductors, and a #10 equipment ground ). I am also wary of direct burial plastic-insulated cables, due to a severe gopher problem on my property. Several times over the years, I have had to replace the 24VAC underground irrigation valve control cables, due to gopher damage.

[SunEagle]

As I recall, we pulled 4 #6 and a #8 through 220' of pretty much straight 1.5" PVC with
plenty of wire hanging out the ends. I would hate to try pulling that around even one
right angle. All that was underground, then an angle and 2 foot riser were glued on to
the ends to bring it out of the ground to a box. Bruce Roe

That is why they make that Blue and Yellow pulling soap. It does cut down on the friction but you have to use the correct one for either inside or outside conduit runs or that stuff hardens up like concrete.

[bcroe]

Yes - 360-degrees of bends.
(could be four 90s, or two 90, three 45s, and three 15's. Or any other combination)

BUT IIRC, I think C/LB/LL/LR aren't allowed to be buried. Couldn't point you to what section
of code that's from offhand though.
A christy box with a heavy or locking cover is how you should do a pull point.

As I recall, we pulled 4 #6 and a #8 through 220' of pretty much straight 1.5" PVC with
plenty of wire hanging out the ends. I would hate to try pulling that around even one
right angle. All that was underground, then an angle and 2 foot riser were glued on to
the ends to bring it out of the ground to a box. Bruce Roe

[foo1bar]

Off the top of my head I believe there is also a maximum of 4 of 90 D bends allowed in a conduit run before you are required to add a fitting (C or LB) or box as a "pull" point.

Yes - 360-degrees of bends.
(could be four 90s, or two 90, three 45s, and three 15's. Or any other combination)

BUT IIRC, I think C/LB/LL/LR aren't allowed to be buried. Couldn't point you to what section of code that's from offhand though.
A christy box with a heavy or locking cover is how you should do a pull point.

[SunEagle]

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.

Off the top of my head I believe there is also a maximum of 4 of 90 D bends allowed in a conduit run before you are required to add a fitting (C or LB) or box as a "pull" point.

You can also rent those blowers that will push a "plug" with a "pull" string attached through a long conduit run.

[foo1bar]

I couldn't find a specific NEC prohibition re "gluing PVC around the wires,

https://ia700805.us.archive.org/20/items/gov.law.nfpa.nec.2011/nfpa.nec.2011.pdf

300.18

PVC conduit is a raceway - and it says raceways shall be installed complete "prior to the installation of conductors"

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'd look at another option if possible...
Maybe a direct-burial cable would be better option. (Not sure what the rules would be for that - haven't had to look into that)
With your current plan - I'm not sure how you'd transition to liquid tight flex.
And I don't know how well that's going to work pulling through 50' of it as it snakes around trees and such.