Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

1235710

Comments

  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    BB. wrote: »
    Those "ferrites" might be current transformers for some sort of AC monitor (like a TED or similar).

    I have the CTs connected to true RMS AC watt hour transducers with pulse output, made by Continental Controls. These transducers feed a Web Energy Logger made by OurCoolHouse. My real time analysis is at http://welserver.com/WEL0043/.

    I'll be adding my solar PV system's performance to this system - will be visible to all.

    Best regards,

    Bill
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    What Pv watts can't do is derate for shadowing. I honestly wish you the best of luck, and I look forward to the performance numbers especially in the fall when the sun is lower and the leaves are still on the trees.

    Tony
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    All 36 panels (Astronergy 225 W ea., 8.1 KW DC total) are up on the roof now (image at 12:00 PM CST):

    original.jpg

    Other than for commissioning and testing, the system cannot be left turned on, as no final City inspection has occurred yet, nor from other entities (i.e., Oncor, the transmission delivery utility).

    I did some spot check 'science experiment' measurements during the day just to see what the numbers might look like.

    Thinking morning cold (31° F ambient) might produce a large array Voc, at 8 AM (CST), Voc was 400 VDC (3 x 12 array design, spec panel Voc = 37.3 V, spec string Voc = 448 V).

    Looking for a high Wm, I checked it at 1:30 PM. All panels were in full sun. Wm = 4940 W AC @ Vm = 311 VDC. This Wm is 79% of the PVWatts estimated KW (6.2) when assuming no shade (using 0.770 DC to AC Derate Factor). (I don't know what panel temperature is - outside ambient is about 49°. And I don't know how much actual azimuth, tilt, and weather conditions affected actual solar irradiance - the 6.2 kW reference number is based on 1000 W/m2.) Voc was 410 before the inverter synchronized up. I gave the inverter's MPPT function about 10 minutes to settle down before noting the Wm and Vm measurements.

    Voltage and power values are as reported by the Sunny Boy 7000 inverter.

    One thing interesting of note: my 3 wire single phase service is not balanced, as reported by the inverter: 124 V vs 122 VAC.

    I went outside and observed the utility power meter to see that it indeed does spin backwards. Thinking about this further, I realized my home's monitor system may show excess power going out to the grid even though I haven't changed out the power monitor unit to a model that can measure positive and negative energy.

    Indeed it did show up, as shown below (red line). Looks like for a couple of my tests I had an excess of about 2000 W AC, which went to the grid, as evidenced by the negative going spikes.

    original.jpg

    Best regards,

    Bill
  • Watt
    Watt Solar Expert Posts: 32
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    I just want to keep up with the thread and subscribing.

    I've really enjoyed watching this thread. Thanks all.
  • FreeWatts
    FreeWatts Registered Users Posts: 14
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    i have also been watching this thead and thanks to all involved as it has been very educational. :D
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Keep us posted, I am going to be very interested in the numbers.

    Tony
  • sub3marathonman
    sub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    a0128958 wrote: »
    Some new learning about wire sizing associated with device labeling:

    For a 40 Amp back-fed solar AC circuit to the electric service panel, this would normally be 8 AWG wire from the inverter AC output, through the AC Disconnect Switch, through the solar kWh meter socket, and on to the service panel.

    The inspector pointed out the solar kWh meter socket is labeled for a minimum wire size of 6 AWG. Thus #8 wire is not acceptable for incoming or outgoing wires at the solar meter socket.

    8 AWG, coming out of the inverter's AC output, to the AC disconnect switch, is fine because the switch is labeled for a minimum wire size of 8 AWG. But from this point, to the meter socket, and on to the service panel, it needs to be 6 AWG due to the meter socket's labeling.

    The circuit breaker stays at 40 A.

    I further learned the common minimum meter socket current size is 60 A, which dictates the minimum 6 AWG wire label. And I learned it's not common to find smaller than 60 A meter sockets.

    The 2 images I posted earlier, for discussion on the neutral wire, are applicable here too.

    Next: Ground wire specifics between the inverter and the electric service panel.

    Best regards,

    Bill
    Any licensed and experienced electrician would have done these properly and further points to the abundance of errors your installer has done. I'm posting this as your update seem to let the installer off the hook, everything wrong with this install, and its become the poster child of how not to do a PV system points to a company that's clueless about NEC and UL requirements for PV installations.

    Based on Solar Guppy's comment, and only as a non-expert trying to be helpful, when you upsize the wire from #8 AWG to #6 AWG on the 40 amp breaker, you must also, according to NEC 250.122(B), upsize the Equipment Ground Conductor (EGC). The requirement is to upsize the EGC a proportionate amount based on the ratio of the circular mil size of the upsized current carrying conductor to the required current carrying conductor. Also, as a technical point, the EGC cannot be larger than the current carrying conductor either.

    I learned this lesson the hard way. According to the NEC it is possible to use the conduit as the EGC. BUT, the local inspectors wouldn't hear of it, so I needed to run the wire. The next problem was that I had already calculated the conduit size and installed it based on the original NEC rules. So I had to now run another conduit with the second array's wiring, instead of one conduit with both arrays, because it would have violated the NEC conduit fill rule. So then I upsized all the wire sizes to reduce the losses, and used the NEC 250.122(B) to calculate the correct EGC wire size.
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Watt and FreeWatts, Icarus, SG, et all, I appreciate the comments. I've learned a lot from many contributors here at the NAWS forum. I hoping to make a return contribution.

    Schedule for near term:

    City inspection early next week.

    Power monitoring instrumentation parts arrive late next week. Will allow me to record / publish solar real time instantaneous AC power (Watts) and energy (kWh).

    I don't know when the Oncor (transmission delivery utility) inspection will be. I believe my service entrance utility meter has to be changed out by Oncor.

    I believe it's not until this step that the system can be turned on.

    I have a pyrometer with a 1-wire interface that can 'talk' to my instrumentation system. I may install it in for short term. In addition to reporting instantaneous irradiation, my system can also do the integration to provide insolation.

    I've got some pyrometer waterproofing to do before I can do so, though. And since it only measures at a specific spot, wherever placed, I'm not sure it would be representative of the diversity of the roof's exposure to the sun.

    I'll post updates as they occur.

    Best regards,

    Bill
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    ... The requirement is to upsize the EGC a proportionate amount based on the ratio of the circular mil size of the upsized current carrying conductor to the required current carrying conductor. Also, as a technical point, the EGC cannot be larger than the current carrying conductor either.
    ...

    This is an interesting subject. Thanks for commenting. I'll look at what I've got for my EGC and respond back.

    Best regards,

    Bill
  • solartek
    solartek Solar Expert Posts: 69 ✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    Based on Solar Guppy's comment, and only as a non-expert trying to be helpful, when you upsize the wire from #8 AWG to #6 AWG on the 40 amp breaker, you must also, according to NEC 250.122(B), upsize the Equipment Ground Conductor (EGC). The requirement is to upsize the EGC a proportionate amount based on the ratio of the circular mil size of the upsized current carrying conductor to the required current carrying conductor. Also, as a technical point, the EGC cannot be larger than the current carrying conductor either.

    The EGC can most certainly be larger than the largest current carrying conductor. There may be practical limits based on the installation but I'm not aware of any "technical" reason limiting the size of the EGC.

    Scott.
  • System2
    System2 Posts: 6,290 admin
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Hi, Bill

    This is Wanshu from Astronergy Solar. I am trying to send you a private mms but failed. Thanks for choosing Astronergy Solar panels and we are very glad to see your posted project picture here.

    Can you leave me a message? My mailbox is wanshu.hu@astronergy.com
    I want to discuss something with you.

    Thank you very much.

    Wanshu
    From Astronergy Solar
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    ... when you upsize the wire from #8 AWG to #6 AWG on the 40 amp breaker, you must also, according to NEC 250.122(B), upsize the Equipment Ground Conductor (EGC). The requirement is to upsize the EGC a proportionate amount based on the ratio of the circular mil size of the upsized current carrying conductor to the required current carrying conductor. Also, as a technical point, the EGC cannot be larger than the current carrying conductor either...

    Here's the Grounding Design, starting at the Electric Service Panel, then going backwards to the Solar Panels. While I have a significant technical background, grounding theory is something I'm unfamiliar with. I welcome any comment on the grounding design.

    medium.jpgmedium.jpgmedium.jpg

    At Service Panel's Ground bus (common to Neutral service wire and Neutral bus):
    • ? AWG bare wire to grounding rod at service entrance, and another to entrance conduit and on to service meter box chassis.
    • ? AWG insulated wire to cold water pipe (4 AWG or larger - actually connects next to Neutral service wire in Service Panel).
    • 6 AWG insulated wire to solar kWh meter's neutral/ground connection - no other connections.
    • 8 AWG insulated wire to solar AC Disconnect Switch box's chassis and on to inverter's AC Ground terminal.
    • (no connections to solar related conduit connection)
    • Solar related current carrying conductors are 6 AWG (240 VAC, single phase, 3-wire).
    • Inverter backfeed circuit breaker is 40 Amps (2-pole).
    At Solar kWh Meter:
    • 6 AWG insulated wire from Meter's Neutral/Ground bus to Service Panel's Ground bus.
    • (no connections to incoming or outgoing conduit connections)
    • (don't know if Neutral /Ground bus is connected to box chassis)
    • Current carrying conductors are 6 AWG.
    At Solar AC Disconnect Switch:
    • 8 AWG insulated wire from Switch's box chassis to Service Panel's Ground bus (no connection to solar kWh meter / box on way to Service Panel).
    • Same 8 AWG insulated wire also goes to inverter's AC Ground terminal.
    • (no connections to incoming or outgoing conduit connections)
    • 8 AWG current carrying conductors from inverter change to 6 AWG at this point.

    medium.jpgmedium.jpg

    At Inverter:
    • 8 AWG insulated wire from AC Ground terminal to AC Disconnect Switch box chassis (and then direct to Service Panel's Ground bus, bypassing solar kWh meter box chassis.)
    • 8 AWG insulated wire from Inverter's DC Ground terminal to attic junction box (goes on to panel rails as 10 AWG wire)..
    • (don't know if inverter's AC and DC ground terminals are connected internally)
    • (don't know which, or if either AC or DC ground terminals, is connected to Inverter's chassis)
    • 8 AWG AC current carrying conductors.
    At (metal) Attic Junction box:
    • 8 AWG insulated wire from Inverter's DC Ground terminal changes to two 10 AWG insulated wires, going on to Roof Top Junction boxes.
    • Same 10 AWG wire connects to metal junction box.
    At (plastic) Roof Top Junction boxes:
    • 10 AWG insulated wire changes (connects) to 6 AWG bare wire.
    • 6 AWG bare wire goes to Solar Panel rails.
    At Solar Panel rails:
    • 6 AWG bare wire 'snakes' continuously to each rail section.
    • Panel's are grounded to rails via WEEB or Unirac manufactured fittings.
    Best regards,

    Bill
  • Art
    Art Solar Expert Posts: 32
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Wow, at 14 pages I thought the panels would have been on the roof pages ago! :D

    Maybe you could send the installer a link to this thread.
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    wanshu_hu wrote: »
    Hi, Bill

    This is Wanshu from Astronergy Solar. I am trying to send you a private mms but failed. Thanks for choosing Astronergy Solar panels and we are very glad to see your posted project picture here.

    Can you leave me a message? My mailbox is wanshu.hu@astronergy.com
    I want to discuss something with you.

    Thank you very much.

    Wanshu
    From Astronergy Solar

    Dear Mr. Hu, it's a privilege to hear from Astronergy.

    I will respond to you, via your email address noted above, either tonight or tomorrow (Dallas time).

    Best regards,

    Bill
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Looking at the pictures in post #124, after the concern early in this thread about shading, at least from the perspective of this picture, instead of putting the 9 panels on the off side of the garage so that they don't get sun until after noon, might you have been able to put ~5 more above the top tier on the main roof, (maybe by moving the roof vent). and then put the remaining 4 on the roof facet by the satellite dish?

    That way, all the panels would be on essentially the same facet, instead of 3/4 of them on one facet and 1/4 on another facet, especially a facet that doesn't even get sun until after noon.

    What time of the day does the shadow from the chimney come off the top panels on the left array? What is venting trough that chimney? A real fire place? Gas log? If the latter the chimney could be replaced with a simple (er) vent, allowing room above the top tier for a couple of more panels.

    I think that Solar Guppy (whose expertise rivals nearly anyone when it comes to grid tie) expressed some concern that the system was going to under perform. Perhaps some changes can be made in the event that the system doesn't preform to expectations.

    Tony
  • sub3marathonman
    sub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    solartek wrote: »
    The EGC can most certainly be larger than the largest current carrying conductor. There may be practical limits based on the installation but I'm not aware of any "technical" reason limiting the size of the EGC.

    Scott.

    That is incorrect, at least according to the NEC.

    For NEC 250.122, there are two subsections.

    If you don't upsize the current carrying conductor then (A) applies, and states "equipment grounding conductors of the wire type shall not be smaller than shown in table 250.122, but in no case shall be required to be larger than the circuit conductors supplying the equipment." I suppose if you really wanted to be technical, with (A) solartek's statement could be correct, since it isn't "required" if you just upsize it because you have the larger wire or some other non-required reason. However, I think it would be missing the intent of the rule.

    Now, if (A) doesn't apply, you must follows the rules of (B).

    However, at least how I read 250.122(B), the NEC states, "where ungrounded conductors are increased in size , equipment grounding conductors, where installed, shall be increased in size proportionately according to the circular mil area of the ungrounded conductors." The key word is "proportionately." So if, on a 15 amp circuit for example, you increase the EGC from a required (according to the NEC) 14AWG to a 2AWG, that would not be "proportionately" if you increased the current carrying conductor from a 14AWG to a 12AWG.

    Also, it may occasionally be required to increase the size of the wires based on the length of the wire run. I think the NEC spells that out too in another section.
  • tvoss265
    tvoss265 Registered Users Posts: 4
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Yes, the EGC can be larger according to the NEC.

    The NEC says it is never required to be larger, but does NOT prohibit it from being larger - "in no case shall be required to be larger than the circuit conductors supplying the equipment".
  • sub3marathonman
    sub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    As I said, the EGC may possibly be larger, if you want to be very technical and in my opinion ignore the intent of the rule, for 250.122(A), but not for 250.122(B) where the current carrying conductors have been oversized, which states, "shall be increased in size proportionately." Thus there is no option.
  • solartek
    solartek Solar Expert Posts: 69 ✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    As I said, the EGC may possibly be larger, if you want to be very technical and in my opinion ignore the intent of the rule, for 250.122(A), but not for 250.122(B) where the current carrying conductors have been oversized, which states, "shall be increased in size proportionately." Thus there is no option.

    You're reading the rule backwards. 250.122(B) is talking about increasing the size of the EGC proportionally if you increase the size of the ungrounded conductors. Not the other way around. And 250.122(A) clearly states that the EGC conductor size can't be smaller than what is given in Table 250.122, and can't be required to be larger than the ungrounded conductors. But nothing in 250.122 puts any limit on the maximum size of the EGC.

    And note I'm referencing 2008 NEC in case your looking at an older version.

    Scott.
  • sub3marathonman
    sub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    solartek wrote: »
    You're reading the rule backwards. Scott.

    YES, I see it now. You're right.
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Not bad. Here's my quicky impressions:

    As to the roof box - it's a good box, and I don't think that ice/snow buildup will be an issue (no more so than the rail mounts anyway). I would like to see more goop - I would have laid it on thick all around the entire box and would have covered those screw heads as well. If they are common drywall screws they WILL quickly rust and they are already quite brittle right out of the box - not so much of an issue if they are mild-steel anodized deck screws. (I love drywall screws, but I don't use them outdoors - outdoors I use deck screws...same ease of use but they weather better.) But it's buried now so...

    I note that the wirenuts used in the roof box are filled with what looks like dielectric silicone grease - I like that.

    The original electrical panel install is clean. I note the use of a spare scrap of wire to tie a bundle of wire (upper right) - this is an old trick from before zip ties became common. There are two methods; A) spiral wound as in this example, and B) wrap once around and then twist/cut with lineman's pliers much like a twisted connection before wirenutting...except cut much shorter to only have one or two twists - and of course you don't strip the ends of the tie wire. Either way is good (personally I use method B because I think it's stronger) and both usually indicate some "Old Schooler" did the work. I still prefer this method over zip ties in a panel - it's often easier to install than zip ties, and it's a LOT easier to remove if you need to.

    [Anectode: Once, I did a complete rewire of a house from the 1920s. Replace all knob and tube throughout with flex and pulled wire, and of course new panels. While waiting around one day to meet with the inspector, I was in the basement cleaning up the wire in a sub-panel. I was using method B above. The inspector snuck up on me, and was watching over my shoulder - for how long I don't know. When I finished and turned around - there he was.

    He said, "That's clean work. I haven't seen many people still using that old way of tying the bundles. Did you do this entire job?". I said, "Yup, it was my job from start to finish." He said, "Well, that's good enough for me, if this is the kind of work you do, I don't need to see anything more. Where's the card so I can sign it off?" (I have my suspicions that he may have snuck a peek at the work upstairs before he found me in the basement.)

    That's the same job where I had to take down, disassemble, pack and store, then later unpack, reassemble and reinstall two hand blown antique chandeliers (that had been converted from gas to electric at some point in their lives) that were insured for about $200,000 each - talk about "pucker factor" - but that's another story. :)]


    Being a stickler, I would have tried to set the new meter socket at the same height as the existing. Maybe not practical, I can't really tell while backseat driving.

    I'm not wild about that free floating section of EMT between the new meter socket and the disconnect. I would have preferred to see it snug against the wall with a strap in the middle - it looks like it's probably long enough to have made back to back offsets and still have the center touching the wall. Not required, but have I mentioned that I'm picky? (I've had to repair so very many broken pipes, connectors and couplings that I'm now a card-carrying strap fanatic.) As it is...I'd be tempted to screw a block of wood to that wall under the EMT and strap to that. Maybe that's just my California Quakey-Shakey background showing through though...

    In the lower left of the new meter socket, it looks like that wirenut is very close to the side of the box. It seems to indicate that the neutral coming in from the left is too short. Maybe not, can't really tell from here. If it IS too short, that could become a strain point tending to pull apart the connection in the wirenut. Having a neutral connection come apart is usually "not a good thing".

    Two ground wires: Well...that may be because the inspector didn't want to see a cut ground wire in that box. It might have been okay to strip an inch or two of insulation, and pass the grounding conductor through the grounding lug(s) UNBROKEN. I think the deal there is either A) inspector's privilege or B) local code requirement. "I don't recall" (default answer when being questioned by girlfriends or judges) any specific NEC requirement to run two independent grounds. (If someone can point to an NEC section that does require an separate equipment ground for the inverter it would be appreciated.)



    I'm curious, what did you finally end up using to tie the PV wire to the rails?
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    icarus wrote: »
    ... might you have been able to put ~5 more above the top tier on the main roof, (maybe by moving the roof vent). and then put the remaining 4 on the roof facet by the satellite dish?

    ... all ... panels would be on ... same facet, instead of 3/4 ... on one facet and 1/4 on another facet ...

    What time of the day does the shadow from the chimney come off the top panels on the left array?

    What is venting trough that chimney? A real fire place? Gas log? If the latter the chimney could be replaced with a simple (er) vent.

    ... Solar Guppy (whose expertise rivals nearly anyone when it comes to grid tie) expressed ... concern ... system was going to under perform. Perhaps ... changes can be made in ... event ... system doesn't perform to expectations.

    Tony, thanks for the suggestions / comments.

    I took some time to look at the economics of grid-tie systems when installed by an installer.

    For roof-top systems implemented by professional installers, here in TX at least, I believe the economic 'sweet spot' is defined as systems that:
    • don't cause damage to the structure over the lifetime of the structure (i.e. don't ever leak water into the structure or allow panels to blow off the roof);
    • meet all NEC and municipality requirements, and NABSEP recommendations;
    • and perform at 80% or greater of PVWatts estimated performance defined as all panels at default azimuth and tilt and a 77% DC to AC De-rating factor.
    In fact, the 2nd and 3rd (NEC / municipality) items are specific requirements of the utilities granting rebates to installers here in TX.

    So from a non-DIY perspective, I would think an installer would limit the size of proposed-to-be-installed systems to achieve the economic 'sweet spot' as defined above.

    While I don't know much about roofing, I would think the cost to be pretty significant for relocating a wind turbine. Same, probably more so, for relocating a chimney (it's a real fire place using a non-masonry flue, BTW).

    Putting panels on the roof area where the satellite dish was looked at. Most everyone, like you, saw this area as nicely available. Unfortunately, it turns out there's room for only 1, maybe 2 panels, depending on fire code 'walk around' requirements.

    Shadowing of the top most panel on the western most 8 panel area appears to stop at about about Noon on a day similar to Dec. 9th. Here's the Noon shot:

    medium.jpg

    I am highly respectful of SG's vast contributions, including here at this forum.

    The first of inspections occurs today (City). After a couple more inspections by the Utility (yet to be scheduled), the system can be started up. I'll have numbers to illustrate performance. This is a good 'science experiment' to understand many factors that influence performance.

    Best regards,

    Bill
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    dwh wrote: »
    Not bad. Here's my quicky impressions:

    ... roof box ... would like to see more goop - I would have laid it on thick all around the entire box and would have covered (deck) screw heads as well. If they are ... drywall screws they WILL ... rust and ... are ... brittle ... out of the box - not ... an issue if ... mild-steel anodized deck screws. (I love drywall screws, but I don't use them outdoors - outdoors I use deck screws...same ease of use but they weather better.)...

    ... wirenuts used in the roof box are filled with ... dielectric silicone grease - I like that.

    ... (neutral) wirenut is very close to the side of the box. It seems to indicate ... neutral coming in from the left is too short. Maybe not ...

    ... I don't recall ... NEC requirement to run two independent grounds.

    ... what did you finally end up using to tie the PV wire to the rails?

    Dhw, thanks for the interest and contribution (and interesting anecdote).

    Interesting comments on longevity of drywall screws that I didn't know - thanks.

    The wirenuts used outdoors are listed for outdoor use, and I believe come with the dielectric silicone-like substance already in the nut.

    I redid the image of the solar kWh meter box, more clearly showing the neutral wire connection. There's plenty of wire - it was just a bad photo.

    Since the two-ground-wires request of the inspector was of a minor nature to proceed to do, I don't think anyone questioned simply getting on with it and doing it, regardless of NEC requirement or not.

    I don't know what was used to tie PV wire to the rails. I don't have ability to get on top of the roof to look. I don't have any reason to believe the installer didn't use something satisfactory to what the City inspector asked for.

    Best regards,

    Bill
  • halfcrazy
    halfcrazy Solar Expert Posts: 720 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    I just went threw all 15 pages. I am really in awe at how some people can call themselves professional's.

    Questions
    1-what did the installer do to fix the attachment of the L feet?

    2-Why not use something like the soladeck on the wires not boxes gooped to the roof? they are about 40 bucks each here is a link http://aeesolar.com/catalog/products/H_ASW_ED_AC_SDK.htm

    3-Did the installer not use any tools to do a sight survey like this one linked? http://www.solmetric.com/

    I apologize if I seem like I am slightly peeved but this is what gives us installers a bad name. Think about it there are 130 other installs out there and you at least had some of the issues addressed. This kind of reminds me to the thread of the roof fire caused by the PV panels that where professionally installed and appear to be Homemade.

    Sorry to Crap on you're shiny new solar system I just see to much of this. Keep an eye open for roof leaks and keep us posted on the systems performance.
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    halfcrazy wrote: »
    ...

    Questions
    1-what did the installer do to fix the attachment of the L feet?

    2-Why not use something like the soladeck on the wires not boxes gooped to the roof? they are about 40 bucks each here is a link http://aeesolar.com/catalog/products/H_ASW_ED_AC_SDK.htm

    3-Did the installer not use any tools to do a sight survey like this one linked? http://www.solmetric.com/

    ... Keep an eye open for roof leaks ...

    keep us posted on the systems performance.

    The L feet remain installed as illustrated - I did not ask for change. Lag screws are installed through the L feet and then the roof shingles, and then into the attic rafters, with construction adhesive liberally applied to prevent rain water penetration into the attic. The solar panels cover the L feet, preventing direct exposure to sun UV and rain. The L feet also have flashing installed 'up hill' to each L foot to redirect rain water around the L feet.

    The installer willingly replaced the 2 on-the-roof wet location Bell switch boxes with Carlon molded nonmetallic NEMA 6P rated junction boxes. These boxes have stainless screws, are designed to withstand the corrosion effects of direct burial, and are rated for protection against hose-directed water and external ice formation. Each box is covered by a solar panel and is thus not exposed to direct sunlight UV or direct rain. Flashing is installed 'uphill' to each box to direct rain water around each box. I did not ask for boxes with integral flashing, nor was it offered.

    I don't know any details on how site surveys were done for my project. The installer did have instrument(s) and used them while on the roof. No survey / shading data has been shared with me.

    Since I have geothermal heating and cooling systems in my attic, with a lot of associated water pipe connections, I routinely inspect in the attic for leaks. I've added to my check list to look for any leakage associated with the 2 solar related roof penetrations. There are no leakage problems currently.

    See my next posting on preliminary performance information.

    Best regards,

    Bill
  • a0128958
    a0128958 Solar Expert Posts: 316 ✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Here's an update status on the project:

    Yet to occur, before the system can be permanently turned on, are final City inspection, completion of application submittal to the utility, and a couple of inspections from the utility company.

    NEC/City required labels are in place now.

    Meanwhile I've spent some time recently putting in instrumentation to provide education on how the system works. For example, my son's Environmental Science class is monitoring the system's progess.

    With today being what I thought would be a cloudless day, I decided to make it a test day. While it didn't turn out to be cloudless, nonetheless it was a good day to verify the instrumentation is working and the numbers are correct. Since today's weather included some high clouds, the numbers today won't be illustrative of max (Winter season) solar system performance.

    Details of the testing are at http://welserver.com/WEL0043/. Since I don't plan on turning the system back on until the remaining inspection / application process is complete, a lot of the solar activity related numbers will 'roll off,' though. Thus, here's a summary.

    The system started producing power at 7:41 AM (Dallas - CT), and stopped at 5:40 PM. It produced 23 kWh. I was able to use 13 kWh to offset consumption; the remaining 10 kWh was exported. Production got up to a max of 5521 Watts at 1:22 PM. Compared to 8.1 KW DC, this is 0.68. Compared to 80% of the PVWatts 0.77 default, 5521 was 111%. Again, skies were not cloud free.

    Here's the summary from a portion of one of the monitoring screens:

    original.jpg

    This last chart shows actual solar power (Watts). The blue line is Wmp. The green line is the portion of Wmp consumed, and the red line is the remainder that was exported.

    original.jpg

    Best regards,

    Bill
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    sidenote:
    this may be long overdue, but i've stickied this thread as i should've done from the start up with the general pics and systems sticky. this one was just too big to include in the other sticky so it is there separately.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    Any news on this yet? Are you up and running? How are the numbers?

    Tony
  • newenergy
    newenergy Solar Expert Posts: 291 ✭✭✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area
    newenergy wrote: »
    I forgot about this, but I started a thread on this subject once before.

    http://forum.solar-electric.com/showthread.php?t=5904

    I think on my next job I'm going to connect with MC connectors inside the j-box. We do a lot of MC connectors anyway, we have the equipment up there on the roof, it makes a solid, water-tight connection and is disconnectable.

    I did the most recent roof transition box like this. What do you think?

    mcinbox.jpg
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    > I did the most recent roof transition box like this. What do you think?

    Too crowded in there, no room to work. Is that tape on the connectors? Was there a label or writeing on the tape?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,