Pre wire or chase on new build

lipets
lipets Solar Expert Posts: 61 ✭✭
Building a new home soon want pre plan the wires from the panels to the main box this will be a grid tie install, not sure of the size yet just want to run chases at this point.

It will be a vacation home for primarily two people, it will be passive solar typical fridge DW, point of use HW, one 9K Mini split

The solar roof panel area is 14x40

tks

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    If it is grid tie--Then really all you have to do is size the Main Panel appropriately for the home. A small home may use a 125 amp service. A larger home may use a 200 amp service.

    And you can play with the numbers:
    • 200 amp service + 200 amp main breaker => 20% of panel rating for solar = 40 amps @ 240 VAC service to GT solar
    • 200 amp service + 175 amp main beaker => 40 amps + 25 amps = 65 amp 240 VAC to GT solar
    • 125 amp service +> 20% = ~25 amp branch circuit for GT solar
    Note that GT Solar economics (and regulations) are highly dependent on your state and actual electric utility.

    Also, if your usage is seasonal--Many plans are setup to "net zero" electrical (or electrical $$$ billing) per year. You may be able to justify a smaller array when you are there weekends. And a larger array if/when you are there full time.

    Do you have any idea about your kWH per month (winter/summer)? Have you checked with your utility/local installer for the rate plans that are offered?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • JoshK
    JoshK Solar Expert Posts: 232 ✭✭
    BB. wrote: »
    • 200 amp service + 200 amp main breaker => 20% of panel rating for solar = 40 amps @ 240 VAC service to GT solar
    • 200 amp service + 175 amp main beaker => 40 amps + 25 amps = 65 amp 240 VAC to GT solar
    Why a larger system on a smaller breaker?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    You are allowed to "over size" the main panel by 20%.

    200 amp box can have 240 amps of source current (with gt solar).

    240 rating minus 200 amp main breaker equals 40 gt solar branch circuit.

    240 amp rating minus 175 amp main breaker equals 65 amp available for gt solar branch circuit(s).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lipets
    lipets Solar Expert Posts: 61 ✭✭
    BB. wrote: »
    Note that GT Solar economics (and regulations) are highly dependent on your state and actual electric utility.

    Also, if your usage is seasonal--Many plans are setup to "net zero" electrical (or electrical $$$ billing) per year. You may be able to justify a smaller array when you are there weekends. And a larger array if/when you are there full time.

    Do you have any idea about your kWH per month (winter/summer)? Have you checked with your utility/local installer for the rate plans that are offered?

    -Bill

    thanks Bill shou;ld have said this new home will be in the NW corner of GA, I don't see any state incentives at all.

    I live in central FL now my bill last month was about 650kWH, (at that, about $100 a month) but I run a pool and elec/heat//AC in conventionally insulted 3 year old home 1800 sqft
    but not a passive super insulated like I'm building GA.

    The solar in my Signature is on our motorhome ans we ran off grid no problem
  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    Ya, put in a 200A service and run 3/4 EMT conduit from the roof down to where the inverter will be. In the attic, make sure the conduit stays at least 10" below the roof to satisfy the new code so when your house is on fire the firemen won't cut into it.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Probably one of the biggest choices you will have (besides having a south facing roof, with correct pitch, no shade) is the choice of roofing materials. Hard tiles (clay, etc.) are very labor intensive and difficult to get a reliable/weather proof installation.

    Asphalt shingle--Even the 40-50 year brands can have issues in as little as 20 years. Steel roofing seems to be an interesting option these days--But I have not talked or read about anyone doing a solar array mounting over a steel "shingle" type roof.

    The steel roof I put on my last house (don't want to redo my roof again in this life) has ~1.5" battens under the steel tile. You do have to be careful to walk on the battens or else you will dent the roof.

    Talk with your roofer about your solar plans and see what they recommend for your area.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lipets
    lipets Solar Expert Posts: 61 ✭✭
    solarix wrote: »
    Ya, put in a 200A service and run 3/4 EMT conduit from the roof down to where the inverter will be. In the attic, make sure the conduit stays at least 10" below the roof to satisfy the new code so when your house is on fire the firemen won't cut into it.

    Well no attic, it is being built with SIPS panels, but I can add a chase thru the panels to the general mech area,

    tks
  • lipets
    lipets Solar Expert Posts: 61 ✭✭
    BB. wrote: »

    The steel roof I put on my last house (don't want to redo my roof again in this life) has ~1.5" battens under the steel tile. You do have to be careful to walk on the battens or else you will dent the roof.

    Talk with your roofer about your solar plans and see what they recommend for your area.

    -Bill

    Maybe better off just placing them ground level then I can adjust them from 33-80 degrees from time to time (no leaks). Guess need to size the wire to run about 80-90 feet, but it will be under ground.

    just thinking out loud.
  • lipets
    lipets Solar Expert Posts: 61 ✭✭
    Found Ga has a buyback program, they pay currently .17 cents, not bad!!!

    http://www.georgiapower.com/business...uy-back.cshtml

    I read that they use a bidirectional meter.

    Assuming that now I decided to install the panels guessing preliminary 1500-1800 watts

    So what is the current latest & greatest items I should look at but like to do on tight budget

    Panel type & voltage

    Inverter size brands

    Other equipment??

    diagram of such an install would be very helpful at this point.

    thanks
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    There are several major classes of equipment out there... The standard central GT inverter... Connect a solar array -> GT inverter's input. Connect output to a 240 VAC breaker pair in your main panel. Done.

    A second class is the Micro Inverter... Connect to your 240 VAC breaker pair and run a cable to the roof. Get a wiring harness that connects to each micro inverter. Attach the micro inverter to *typically" one panel, and build out as many as you need. One major brand, you can put up to ~17 panel+micro gt inverters per 20 amp 240 VAC circuit.

    In general, the smaller Central GT inverters are in the 3-5 kWatt range. A sub 2 kWatt installation is pretty small and may not make a lot of economic sense (large inverter, few panels). Also, the input requirements for a Central GT inverter can be pretty limiting... I.e., you have a specific voltage/current range that is supported and it may be "awkward" to get 1,800 Watt array on a Central GT type inverter.

    A micro inverter system (Enphase is one, there are several new mfg. out there now too) may be more flexible for you. You can add ~200 Watt panels+micro inverters at a time. Easy to start small and you can grow out the system a panel at a time.

    The large issue may be--These systems (in most areas) require permits and utility company approvals. Economic factors may make a small (sub 2 kWatt) system not cost effective to install (permit fees, inspection fees, minimum charges for electrician/installers/etc.).

    Many utilities will let the owner self install and have a master electrician sign off on the installation. Other utilities may not let you install any GT solar panels/systems. It all depends.

    There are few threads here showing lots of pictures of the installation process. If you are OK working on a roof--It is not a difficult job to install (other than the basic electrical/code requirements, doing the roof install/flashing/mounting is probably the most work--And best to "get right"--To avoid leaks and other issues down the road).

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

    I do not work for our host NAWS--But since they fund/support the forum here, I would suggest you at least start by looking at their product ranges to get more information/basic pricing.

    http://www.solar-electric.com/inverters-controllers-accessories/gridtiesolar.html

    Also, here is a sticky that talks about the different types of solar power systems out there... One big thing to understand is that a "pure" Grid Tied solar power system only works when there is utility power. If the utilty power fails, the solar panels on your roof do nothing. If you want backup power--You need to plan for it (off grid inverter, hybrid inverter, new GT inverter with emergency 120 VAC outlet when the sun is shinning, backup genset, etc.)..

    battery-less Outback Radian (GT/Off Grid/Hybdrid Inverter options explained)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lipets
    lipets Solar Expert Posts: 61 ✭✭
    OK if I look at the Micro Inverters they are about $130 ea so for instance 8 panels $1050 plus the display control etc add $500, if I follow correctly heavier wire to service panel, so about $1800 for 8 yes I know I can add on.
    I also see the Enphase has had failures, yes they replace but there are failures if the panels are on the roof kinda a PIA.

    I can get a Sunny Boy 3000TL-US Transformerless 3000 for about $1500 and add more panels later on too!

    Costs less for wires and run lighter gauge wire.

    I'm installing myself so that's not a cost factor but it is time.

    Still need to talk to the Folks at GA Power in their solar dept for the details.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Yep. All true.


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset