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  • 8400w Grid Tie System - Kit or piece it together?

    Hey guys...

    After much research and back/forth... my wife and I have decided to install an 8.4kw grid tied solar system on our home. I contacted a local installer and their out-the-door cost was quoted at $23k.

    We just sold our other home which gives us a bit to play with.. but $23k is a big pill to swallow. After contacting our power provider and going over the paperwork for their interconnect requirements, they allow for customer installations as long as everything meets code and passes their inspection.

    With that said, I'm leaning heavily towards doing my own installation (possibly hiring an electrician for the final hook-up).

    Here is the plan currently. My shop has a dedicated 100a circuit from the meter (100a in the shop, 200a in the house with disconnects at the meter for each all installed by an electrician prior to us purchasing the home). The shop only has a circuit for lighting, wall outlets, and my welder so the panel has plenty of room left (space and ampacity). I'm looking at 8400w of panels (28-300w panels, possibly Canadian solar) on the roof with an unobstructed south/east face. For the inverter, I was leaning towards the Sunnyboy 7.0 or 7.7 (both have a peak output of 32a at 240v). Feed through the 100a service panel in the shop. Although my provider doesn't require a disconnect for this style of system, the shop does have one in place just off the meter base.

    I can build racks... mount panels.. run wiring and mount the inverter myself. I can also do the panel work but can hire that out if it is necessary to meet their requirements (although from what I've read and been told by them, it isn't required. Just has to pass their inspection prior to net meter install) I'll pull permits as well.

    Am I missing or overlooking anything?

    Now.. I've been looking at kits such as those from BluePacific but had also priced out individual components. Seems to be cheaper to buy components from Renvu or others then buying the kit. Only thing I'm not sure about is drawing up the required diagrams that my power provider needs. May have to hire that out too or do a bit of research on the requirements for it.

    Anyways.. What would you do? I admit, I don't have a lot of knowledge other then research on here and from what I've been provided from the power company. The idea of a package deal is nice... but it comes with a ~$1500 premium.

    I'm also waiting to hear back from the solar contractor as they also do "material only " builds for those wanting to do their own installs.

    So.. kit or piece it together? The kit seems to just come with panels, inverter, and pv cable. Are there any requirements beyond that (besides electrical fittings, mounting, etc).

    Thanks for any input.
    Last edited by Mr4btTahoe; 03-05-2018, 06:14 PM.

  • #2
    Just because you can build racks, does not mean they are engineered for uplift, or the building they are attached to.
    You will need to get a PE to do mechanical calcs for you, and your city and county may have some say in both the mechanical and electrical side of things.
    Powerfab top of pole PV mount (2) | 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

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    • #3
      Originally posted by Mr4btTahoe View Post
      Anyways.. What would you do? I admit, I don't have a lot of knowledge other then research on here and from what I've been provided from the power company. The idea of a package deal is nice... but it comes with a ~$1500 premium.
      I bought components all from one place (renvu).
      Renvu had a thing to "build your own kit" - and then I added/changed things from there for my needs.

      (both have a peak output of 32a at 240v). Feed through the 100a service panel in the shop. Although my provider doesn't require a disconnect for this style of system, the shop does have one in place just off the meter base.
      Is it a 100A panel or a 125A panel with a 100A breaker?
      32A would be a 40A breaker. Including that, is your total set of breakers less than 100A? (you said "plenty of room" -so maybe it is)
      Is it a 100A breaker at the subpanel or just at the main panel by the meter?

      Are there any requirements beyond that (besides electrical fittings, mounting, etc).
      I bought an MC4 crimper just for my install and a conduit bender.
      And the materials for mounting, and all the electrical stuff from HD/Lowes/etc is a non-trivial cost.
      Figuring out the label requirements took time - but not a huge amount of money.


      First thing I'd do, is I would check with the AHJ about what the permit requirements are. What are they going to require? Are they going to require stamped drawings? If you're doing a ground mount (sounds like you are) - will you need to do a full engineering analysis of the soil conditions, etc?

      Comment


      • #4
        Based on your post....you sound like you are handy.

        My 2 cents is to purchase the parts individually....forget the kits. Create a BOM and stick to it. Get quotes for your BOM from multiple suppliers. Start with these:

        https://www.civicsolar.com/
        https://www.altestore.com/store/
        https://www.wholesalesolar.com/

        There are many more if you care to do your homework. It has been my experience and many others that the more quotes you obtain the smaller the project cost.....it only costs you your time expended.

        Good luck.

        Comment


        • #5
          At this time it sounds like you will encounter things you are unaware of from a cost, engineering and PITA standpoint. If you know everything that can trip you up, and do some smart shopping, it may be possible to get away for maybe a buck/STC Watt, but you've got to know what's up and probably do all or most of it yourself. The engineering and construction costs for a ground mount can be an eye opener. It's a lot more than simply driving posts into the ground.

          Do you know, and equally or more importantly, understand what the POCO requires in the way of conformance ? Look before you leap and don't leap until you are sure you understand what's required from the POCO.

          BTW, how did you come up with 8.4 kW for a size ? Conservation and load reduction pays 2X - once to lower the bill, and once to make for a smaller load that can be met by a smaller array. Just sayin'.

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          • #6
            There is much opportunity to save $ with DIY. BUT the details will keep coming up. It could easily take
            several times as long before its running, compared to paying an installer. That might put you past the
            peak summer months where it really starts paying, till next year.

            Check the total length of that loop out to your shed, and the wire gauge. Then the current flow and
            voltage drop is easily calculated. Too high (below 2% is very desirable) will be costing a bigger fraction
            of your production, and could cause high line shutdown if your voltage is already high (usually is).
            Bruce Roe

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            • #7
              You should look up the NEC code for connecting feeder to a sub-panel. I assume the 120% rule applies as it isn't a dedicated sub. If it's a 125amp busbar, you should be fine with the 40amp breaker for the Sunny Boy 32amp feed. A 100amp busbar in a 100amp panel would only be good for a 20amp breaker with the 120% rule.

              Comment


              • #8
                Originally posted by frankiek3 View Post
                You should look up the NEC code for connecting feeder to a sub-panel. I assume the 120% rule applies as it isn't a dedicated sub. If it's a 125amp busbar, you should be fine with the 40amp breaker for the Sunny Boy 32amp feed. A 100amp busbar in a 100amp panel would only be good for a 20amp breaker with the 120% rule.
                With an additional 40a breaker in my shop's panel, I'd be at 115% if the busbar is 100a rated. The panel only has 1 220v 20a circuit (welder), 2 110v 20a circuits (outlets on north/south walls), and 1 110v 15a circuit (lighting). No plans to add any more. Wouldn't I still be fine?

                As to all the others... I had a long typed out response.. but I guess it timed out as when I tried to post it, it locked up... went back and it was gone. So here is the gist of what I had typed...

                The plan is for a roof mount system going on a 24x40 pole barn with a truss roof system.. 4x6 posts.. 8" pad with proper footers. I'll be talking to a contractor friend of mine about the load being placed on the roof (1400lb @ 125% design factor) but based on some snow load math (although not the "right" way to figure it.. it's the best I can do on the quick. I will be talking to a professional about it though just to verify). Snow weighs on average, 1lb per sq. ft. per inch of depth. On average, the roof sees 6" of snow/ice every year without issue. The roof sides are roughly 40x13.. which equates to roughly 3100lb evenly distributed per side every year on average. So in theory, as long as I do my part and keep the snow off the panels, weight shouldn't be an issue. Again... I'll verify this with a pro... this is just me scratching down some figures to see if it was plausible.

                Going over everything my energy provider has sent me, they don't appear to require much due to the system being under 10kw. Over 10kw, their rules change a bit... but under.. it seems to be standard electrical code, no additional disconnects or special equipment required (although the shop does already have a disconnect at the meter). Their first requirement though is to provide with the application, a description and drawing of the system in which they will either approve or return with additional requirements noted. They do say to contact them with any questions and they will gladly clarify and work with me. I'll be calling them soon to go over the details. Also, the solar contractor I spoke with also offers a service to help DIY folks get through the paperwork and requirements so I may take them up on it.

                Time it takes to get the system up and running wont be an issue if we go the DIY route. Going this route allows us to not finance any of the system. If we go with the contractor, we would be financing a little under half the cost which would be a big turn-off for the wife and would add quite a bit to the break even timeframe. Honestly, I'd really like to avoid going into debt for it. If we can do the leg work and come in at under 10k up front out-of-pocket (not including the federal tax breaks and such), I'd be happy.

                System sizing... we haven't exactly decided for sure.. however 8.4kw would cover the majority of our needs. Based on a conservative 4hrs of direct sunlight.. the array would provide on average, just over 1k kwh per month. Should be a bit higher then that.. but wanted to be on the conservative side. Averaging our usage for this year (which winter was hard... we typically heat with wood making our winters the cheapest season as far as electricity is concerned.. but this year, the weather was changing so often from warm to cold all winter, it was hard to keep the house comfortable which drove up the average a bit).. anyways.. our average this year was ~1250kwh per month (around 800 in the spring/fall to a peak month in winter of 3000kwh). We could probably get away with going a bit smaller... and it would be nicer as the roof space will only allow for 24 panels meaning I'd have to build a ground mount for the other 4. Not a big deal.. but could always just go with 24 - 325w panels instead (7.8kw).

                The run from the meter to the shop's main panel is ~50'. It was installed by an electrician for the previous owner. I'd say as far as wire sizing and such are concerned, it is just enough to meet code for the length of run and the 100a panel. I'll have to check to be certain on size though. How the house/shop are currently wired.. Directly under the meter base is a disconnect panel that has disconnects for the house and the shop. The house has a 200a main panel. The shop has a 100a main panel. This was all setup prior to us buying the house but it passed inspection so I assume it is up to snuff.

                Thanks for all the input guys and keep it coming!
                Last edited by Mr4btTahoe; 03-06-2018, 01:55 AM.

                Comment


                • #9
                  Originally posted by Mr4btTahoe View Post
                  After contacting our power provider and going over the paperwork for their interconnect requirements, they allow for customer installations as long as everything meets code and passes their inspection.
                  Originally posted by Mr4btTahoe View Post
                  Going over everything my energy provider has sent me, they don't appear to require much due to the system being under 10kw. Over 10kw, their rules change a bit... but under.. it seems to be standard electrical code, no additional disconnects or special equipment required (although the shop does already have a disconnect at the meter). Their first requirement though is to provide with the application, a description and drawing of the system in which they will either approve or return with additional requirements noted.
                  You keep saying that you talked to your power company and they require, but have you talked you your AHJ to see wha code requires?
                  Last edited by ButchDeal; 03-06-2018, 08:50 AM.
                  OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                  Comment


                  • #10
                    Make sure to read all documents posted by your power co and your city. Check what versions of code they are on. International building code, international roofing code, international fire code, and national electric code. You will need to comply with all of them. Some examples of the biggest ''gotchas' to know about up front before even considering equipment and array size...

                    Did you leave 3' pathways for firefighting?
                    120% backfeed rule.
                    Rules on where panel is fed from (top/center)
                    City rules on if you require electrical contractor to do any part of it (for instance, some require for final hookup)
                    AlSo they may allow diy, but if you derate a panel they may require you to have an electrician stamp the permit and provide load calculations. Same topic, is derating even allowed?
                    Are supply side taps allowed if needed?
                    how much pound per square ft can you put on the roof before they require structural engineering?
                    how many pounds per attachment point before they require engineering?
                    How many pounds per rafter is allowed?
                    If your roof its going on isn't a modern truss system, are you prepared to hire an structural engineer to validate and provide reinforcing requirements?
                    Do they require calculations for wind and snow?

                    Those are just some examples.. they should have some documentation available to you that outlines all of the PV requirements. Once you read it all and know what constraints you have to work within, it will be easier for these guys to help ya.

                    As mentioned before, you'll have difficulty getting your own racking approved. It is cheaper to buy racking that is already engineered, unless you have a very unusual mounting requirement.

                    It would also be helpful to find any example diagrams they offer. For instance, the city here didn't offer any examples but the power company did, and that cleared up alot of questions I had.

                    Find any installer inspection checklists you can. They may contain even more gotchas. An example is disconnecting nuetral with the disconnect switch may not be allowed, mounting height requirement of gear, switxh must be between 36" and 60" (example only). Does power co require their own meter installed between solar and panel? Probably..

                    Just a few examples of things that if you know about before choosing gear will save you alot of grief.
                    ​​​​​​

                    ​​​​

                    Comment


                    • #11
                      Originally posted by ButchDeal View Post



                      You keep saying that you talked to your power company and they require, but have you talked you your AHJ to see wha code requires?
                      As of right now, no but will be before making any purchases. I'll give them a call today and see what they have to say. I'll have to call the county building inspector and see what kind of insight he can give.


                      -ImInPhxAZ- For the most part, I've got a good bit of your list above covered. County doesn't require anything to be done by an electrician oddly. They only require that once the work is complete, that it will pass their inspection. I'll be giving the building inspector a call and see what they have to say. Hopefully they can give me some insight on other requirements that I may not be considering. Thanks for the advice!

                      Comment


                      • #12
                        Originally posted by Mr4btTahoe View Post

                        As of right now, no but will be before making any purchases. I'll give them a call today and see what they have to say. I'll have to call the county building inspector and see what kind of insight he can give.
                        The AHJ is where you will find the code requirements for disconnects, rapid shut down, racking UL / fire ratings, setbacks, etc. Also don't forget about possible SREC requirements if available which would generally be a revenue grade production meter.
                        OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                        Comment


                        • #13
                          Have a call into the power provider to see if they can send me some more specifics on their inspection requirements. Also called the county building department and they let me know that there is only one permit required ($30) and an inspection by the power company. They gave me the number of the local inspector (code enforcement) and said he'd be glad to give me any info I'd need. I'll be giving him a call later this morning.

                          Comment


                          • #14
                            Clearly you're not in California.
                            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                            • #15
                              Originally posted by littleharbor View Post
                              Clearly you're not in California.
                              Lol... nope. A small town in southern IN... population just over 6k. Love it here... not many other places you can pick up 10 acres of wooded land with a 2200 sq. ft. house and 24x40 pole barn for under 70k. House needed a lot of work.. took a year on the remodel but well worth the effort. Hell, they didn't even require inspection when we installed our wood stove. Of coarse, I contacted the insurance company first.. then the inspector. Installed ourselves with everything surpassing code by a fair bit... no inspection or permits required by county or insurance which surprised me.

                              That's the difficult part in all of this... for an average joe to figure out what code applies to what situation and how to pass it. I'm always willing to learn and to take the time to do things right.
                              Last edited by Mr4btTahoe; 03-06-2018, 11:23 AM.

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