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Texas Off-Grid versus buying power lines

jjminch

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Joined
Feb 21, 2021
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2
I’m looking for some advice on doing a complete off-grid system for my new homestead. Construction on the property is starting soon and I need to decide by next month on how I will power the home.

The power company is estimating at least $12k to run lines to my property. That isn’t including the clearing costs and electrician costs for a meter. I'm guessing it will be $20k. Plus power lines are ugly and I wouldn’t mind doing my part to help environment.

I used to work as a PM for a switchgear/power gen company. I’m not an engineer or a sparky but I’m confident I can tackle most of the work.

Location – Austin TX

Lat 29.99549

Long -97.45226

House/Family – 1600 sq ft living space for family of 5. New Metal Building “Barndo” plus shop space. Will be well insulated using spray foam. Mini-splits for HVAC, plus propane for range/stove and tankless water heater.

Monthly Usage – My current home is nearby but is 3000 sq ft with two large inefficient central air systems. It ranged from 1154 kwh in March to 3314 kwh in August, the average for the year was 1940 kwh.

I’m estimating a 30 percent reduction for the smaller house, my monthly estimate is 1350 KWH. Is this a reasonable assumption?

Panels– Will be ground mount, plenty of space, can get direction/angle “just right”.

AHJ/Regulations – No plans to grid tie this but will be using a construction loan. Need reputable vendors with warrantied product for the major components.

Batteries – What is the minimum storage recommended? 2 days of power? I will have gas generator available to offset low productivity.



Questions:

What specs on batteries storage do I require?

How much PV do I need?

What should I budget for this?

Can I build in expansion capability into the system? Barns, additional homes, etc.

Recommended vendors and reading? Anyone have a similar situation and post a build thread?

Glad I found the site. Thank you in advance.

Josh
 
how tightly sealed is the building? I have a 28x66 morton building with thier full insulation package. I really think this insulation is what makes it all work. I can heat the entire building all winter for $300-400 worth of propane and keep it at 70 degrees. My brother has a similiar sized pole barn without insulation and he is lucky to be around 50 degrees and he burned thru $2000 worth of propane last year. I have 1800AH of battery and a propane generator and a big backup diesel generator. ive got 24 300 watt panels on the roof location is northern Illinois. Ive got washer/dryer, tvs, full kitchen and a hot tub. (hot tub is heated with propane). We have zero grid ties and have never had any power issues. If sun would not shine for days , have 4 75 amp chargers that can run off the generator. To be honest i spent way too much on the generator 30KW Caterpillar.. its rarely used. We used outback solar brand charge controllers and sun power cells but i think there are many brands that would be similiar. I have a direct vent propane furnace ceiling mounted and we went with geothermal cooling , it runs off the battery bank no issues, its just a blower and a pump to circulate the water loop. Our solar runs this barn and a 1700 square foot ranch house. house uses same geothermal well but has its own unit, its also running off the battery bank. House is heated with propane and the ac uses the battery bank.

I could easily add a 3rd building if we wanted to without really doing much more to the solar setup.
 
how tightly sealed is the building? I have a 28x66 morton building with thier full insulation package. I really think this insulation is what makes it all work. I can heat the entire building all winter for $300-400 worth of propane and keep it at 70 degrees. My brother has a similiar sized pole barn without insulation and he is lucky to be around 50 degrees and he burned thru $2000 worth of propane last year. I have 1800AH of battery and a propane generator and a big backup diesel generator. ive got 24 300 watt panels on the roof location is northern Illinois. Ive got washer/dryer, tvs, full kitchen and a hot tub. (hot tub is heated with propane). We have zero grid ties and have never had any power issues. If sun would not shine for days , have 4 75 amp chargers that can run off the generator. To be honest i spent way too much on the generator 30KW Caterpillar.. its rarely used. We used outback solar brand charge controllers and sun power cells but i think there are many brands that would be similiar. I have a direct vent propane furnace ceiling mounted and we went with geothermal cooling , it runs off the battery bank no issues, its just a blower and a pump to circulate the water loop. Our solar runs this barn and a 1700 square foot ranch house. house uses same geothermal well but has its own unit, its also running off the battery bank. House is heated with propane and the ac uses the battery bank.

I could easily add a 3rd building if we wanted to without really doing much more to the solar setup.
Damn a 30kw generator is pretty large. You could run a small ER with that.

The building is not yet built, but I'll be having it spray with closed cell foam after the penetrations, so I would expect it to be pretty tightly sealed.

Any pics of your setup?
 
i will try to post some pictures, have never posted pictures on this site.

I got a steal of a deal on the big generator on my local craigslist , if not for that would never have considered it its rarely used, and it eats diesel. the propane generator is 7.5KW and it can do all except cant run the hot tub with both pumps and the rest of the system off just it alone. It can run either the house or the hot tub but not both... just cuz your off grid doesnt mean you cant have what you want.


FYI local power supplier wanted about $45K to run the power and water lines plus it would have cost me $4-5K to clear the path of trees and shrubs. and a 3-9 month waitlist (must be nice to be a monopoly) . I spent way less and feel i get way more, plus no power bills. I bought a 7000gallon used stainless steel tanker trailer and have a local farmer who has a semi and cdl to fill it up is how we get our water. I sell haz liquid chemical haz tanker shipping for my living so i dont consider that an expense is more of a fixed investment.. those trailers are like gold bars if you just hold onto them they appreciate. Have bought and sold at least 20 trailers over the years and never been upside down on one of them.
 
Look up on this forum what Trukinbear has put in. It includes PV, inverter, diesel generator.
He has estimated generator costs.

If it was possible to get utility power, even a small connection at edge your property that you extended, that would be very handy. Reliable power that is maintained and repaired by their workers.

Otherwise, designing controls for equipment like heating, A/C, well pump so loads are enabled by priority, avoiding multiple large loads at once and avoiding large loads when battery is low, could let you build a smaller and more cost effective system.
Cheaper to store water in a tank and heat in thermal mass than to store the same energy in a battery.

If you go for 2 or 3 days battery, then an FLA forklift battery could have 15 year lifespan at moderate cost. It needs to be fully charged periodically, and will require watering. It may be more cost effective than lithium.
If you size battery for just one night and cycle it 80% every night, then the 2000 to 5000 cycle life of lithium makes it competitive. If DIY, cost can be a bargain. (Small battery, of course you'd have to run a generator any morning the sun didn't come out.)

My system is grid backup, so only occasional cycling. It is sized for 70% DoD overnight and is AGM. (if used every day would only last a couple years.)
I use SMA Sunny Island battery inverters and Sunny Boy AC coupled PV inverters. These are scalable from about 5 kW to 50 kW.

Search for DC Solar trailers, available with or without diesel generator. Some have fresh batteries, some may be in bad shape. They are a complete SMA power system (DC coupled not AC) capable of running your house except only 2400 PV panels installed, would need expansion.
 
This couple are making a lot of money Youtubing their homestead in West Virginia.

Their last video is showing off their 13 kW PV system they just finished upgrading.

 
Homeowner’s Guide to the Federal Tax Credit for Solar Photovoltaics

A solar PV system must be installed before December 31, 2019, to claim a 30% credit. It will decrease to 26% for systems installed in 2020 and to 22% for systems installed in 2021.

What expenses are included? The following expenses are included: • Solar PV panels or PV cells used to power an attic fan (but not the fan itself) • Contractor labor costs for onsite preparation, assembly, or original installation, including permitting fees, inspection costs, and developer fees • Balance-of-system equipment, including wiring, inverters, and mounting equipment • Energy storage devices that are charged exclusively by the associated solar PV panels, even if the storage is placed in service in a subsequent tax year to when the solar energy system is installed (however, the energy storage devices are still subject to the installation date requirements)5 • Sales taxes on eligible expenses.

My tax accountant just said "save all your reciepts"... so you can knock 22% off your analysis in comparing grid to off grid if you get it in by the end of the year....
 
A solar PV system must be installed before December 31, 2019, to claim a 30% credit. It will decrease to 26% for systems installed in 2020 and to 22% for systems installed in 2021.

My tax accountant just said "save all your reciepts"... so you can knock 22% off your analysis in comparing grid to off grid if you get it in by the end of the year....

"The commercial (Sec. 48) solar investment tax credit has been extended at 26% through 2022. Instead of the phasedown to 22% happening on January 1, 2021, the phasedown to 22% will now occur on January 1, 2023. Any project that is placed in service after December 31, 2025 will automatically qualify for a 10% ITC."

 
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