diy solar

diy solar

Does any one make this?

CVdave

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Dec 19, 2021
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Hi there, I am looking to build a system for my new house I am building. What I want to do is: Grid tied solar WITH battery bank to be used as a back up system in the event of grid outages. The inverter output must be 120/240 VAC and be able to supply my 100Amp service. My nominal load will be much lower , I have been thinking of 2ea growatt 5000's in parallel with an auto transformer for creating a neutral. I do not mind using a manual transfer switch. I can see how I can make this work with the growatt, but I cant seem to figuire out how to intigrate the grid tie,, Any sugestions?

Thanks!
 
A few things before you go too far.
1) Do NOT buy a damned thing until you have a plan, without a plan, IS a plan to fail.
2) Be realistic ! 50% of folks under-estimate and require an upgrade within 2 years.
3) Always consider Future-Proofing, some things (foundational components) are not cheap to upgrade/replace.
4) Conservation is always far cheaper than Generation & Storage ! Use efficient appliances & devices, SOFT-START Water Pumps, AC Units etc are a huge saver on system stress & load but power used.

Building a Home:
Build as efficiently as possible, situate it to make use of passive solar capabilities. Make use of Advanced Framing Techniques along with Cool Roof systems (reduces heating & cooling by >25% passively) and smart siding finishing options which provide thermal breaks etc. Try to build using Passive-Haus knowledge & experience, you would be amazed at how much energy can be saved and with little extra cost if done right!

Case in point example: I designed & built my own Hyper efficient home, In summer, outside temp = 40C/104F and has never gone above 27C/80F inside at the peak of the cathedral ceiling. In winter @ -30C/-22F outside, my heating runs 4 hours within a 24hr period to maintain 25C/77F internal Temp (Radiant Heating within a Frost Protected Slab Foundation with 4" of XPS-Foam (r20 double code req) under & around it.
Hyper-Efficient which also lists appliances etc used
NOTE: I designed, did the plans & blueprints and built the house myself, only contracting out the concrete forming & pour and the actual cladding of the roof in metal. Everything else, including milling my own Pine 6" patterned baseboards, casings and moldings all done by me.

My Cabin Overview:
  • 500 Sq Feet, 1 br, 2nd story loft, 9/12 pitch roof (Cathedral Ceilings)
  • FPSF Slab Foundation REF LINK: https://www.finehomebuilding.com/2010/11/11/frost-protected-shallow-foundations-2
  • Radiant Heating in floor (*it's WONDERFUL and efficient) provided by REF: https://www.radiantcompany.com/
  • Cool Roof System (saved 25-30% of Heating & Cooling costs and is incredible ! REF: http://www.houstoncoolmetalroofs.com/cool-roof-information/cool-roof-design-texas/
  • Rain Screen Siding method (used Live Edge White Cedar as my finish) REF: https://www.greenbuildingadvisor.com/article/all-about-rainscreens
  • INSULATION: (All obtained from Commercial Roofers - not available in retail land)
  • -- 4" XPS Under the FPSF Slab and out the sides (wings) 24" providing R20, double code requirement.
  • -- 5.25" High Density EPS-2 Foam between 2x6 studs R32)
  • -- 7,5" Paper Faced PolyISO between Rafters (Cathedral Ceiling, roof is 9/12 Pitch)
  • Appliances:
  • Water Pump: Grundfos SQ-5, Soft Start 120V Deep Well pump, 260' deep pushing to 50 Gal Pressure tank then 75' to Cabin. Max Wattage 1000W @ 45PSI. REF: https://us.grundfos.com/products/find-product/sq.html
  • Unique Offgrid Classic propane cook stove: REF: https://uniqueappliances.com/
  • Danby (Magic Chef same) Apartment Size Energy Star Fridge (uses 220kwh per yr)
  • EccoTemp FVI12-LP On-Demand Water Heater for Hot Water. (not suggested, get a 45 series or better brand !)
  • Takagi TH-3-m Condensing On-Demand Heater (used for Radiant Heating exclusively as I had Antifreeze in my system) (got from Radiant Supplier best deal out there)
    **NB** I run a separate Hot Water System from my Radiant System. The other option is to use one On-Demand unit for both, very possible and not hard, The Radiant Company can design it either way for you, no extra charge, it's a part of their service and I can only PRAISE Them for their amazing work, quality products & support, and I do "not" praise anyone lightly !
The efficiency is a win with the slab & hyper insulation. Winter -30C, inside 25C, Radiant only run 2 hrs within a 24 hour period to maintain 25C (floor sensor). Summer: 35C outside, 21C inside, NO AC or Fans just open windows. Slab itself never goes above 20C in summer, it regulates everything inside. Should Note, I am on the South Face of a Granite Ridge, 1200 foot fall in front of me, this property get's the heat & in a bad heatwave 40C is not a shocker. The Cabin itself is shaded by Scotch Pines & Cedars on the south & west sides and nestled into a forest nook. Solar System is mounted to the side of a 20' Sea Can 50' from Power House.

North American 240VAC is 2x 120V Lines on two legs (split phase)
A 48V System pushing 250A can deliver 12,000W. 12,000W ÷ 240VAC = 50A

Hope this helps you get started on your Journey, Good Luck.
 
You need to do some research for you particular state and the building department for the city or county which in which your home is to be constructed.
For example the state of California maintains a list of inverters that qualify for grid tie connection. Growatt is not on that list. Perhaps you are in another state?
 
I am in the state of Maine. I built an off grid cabin 5 years ago with a solar power system and it has been great.I am building a new house at the moment and I am researching what I have for options. I have been a master electrician since 1993 and have worked as a hydro electric power plant technician for 35 years. That said, I am a bit green with some of the solar/inverter systems. At this point I am attempting to educate myself prior to designing my system.

Thank you for any and all comments!

Merry Christmas from Dave in Maine
 
The Growatt SPF5000 is NOT a grid tie unit. It can take grid input to supplement solar or run off the grid when there is no solar, or even charge batteries, but it will not feed or integrate with the home grid.

If you want to integrate a transfer switch to feed your panel from either the Growatt or grid, then that's a whole different discussion.
 
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