Solar, can I ask some advice about our cabin?

Started by Grammy, December 27, 2022, 07:24:24 AM

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Grammy

@Solar I'm sorry I've not been on for a while.  (We've been attending funerals.)

We have a little tiny house (cabin) in our backyard and we're interested in having it be completely able to function in the event of a power outage.  I'll put a photo of it on this post.  It's a 12x28 building with a full bath and kitchen.  Appliances, etc, include a 9000 BTU mini-split unit, half-fridge, small water heater, microwave, smart TV, coffee maker, toaster and single electric burner.  Right now, it has its own electric panel and draws from our house's lines. 

We've never learned the first thing about solar panels, generators, etc., and don't even know where to start.  I was wondering if panels could be put on the roof, since there are no trees overhanging it? 

All that to say that I'm basically asking how we would get started equipping this little unit to be able to sustain its own power?  (No rush to get to this.  I'll just peek in from time to time.) 

Hope you and Toy had a wonderful Christmas.   :smile:

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Solar

Quote from: Grammy on December 27, 2022, 07:24:24 AM@Solar I'm sorry I've not been on for a while.  (We've been attending funerals.)

We have a little tiny house (cabin) in our backyard and we're interested in having it be completely able to function in the event of a power outage.  I'll put a photo of it on this post.  It's a 12x28 building with a full bath and kitchen.  Appliances, etc, include a 9000 BTU mini-split unit, half-fridge, small water heater, microwave, smart TV, coffee maker, toaster and single electric burner.  Right now, it has its own electric panel and draws from our house's lines. 

We've never learned the first thing about solar panels, generators, etc., and don't even know where to start.  I was wondering if panels could be put on the roof, since there are no trees overhanging it? 

All that to say that I'm basically asking how we would get started equipping this little unit to be able to sustain its own power?  (No rush to get to this.  I'll just peek in from time to time.) 

Hope you and Toy had a wonderful Christmas.  :smile:


No problem dear, sorry you're going through this. Just glad to hear you're doing OK.
So here goes... :biggrin:

We'll make this an open thread so others can ask questions, so I'll give more information than necessary.

My brother bought the very same one. He loves it! I'm going to take a leap of faith and assume this could be a permeant home.

Other wise, simply buy a Kubota Lowboy 7000 (7500 watt surge, 6500 steady output) which is more than enough power. Have it professionally installed. Absolutely avoid gas hybrid models. (Especially avoid Generac, way too many headaches regardless of what you hear, I used to be a dealer)
There are other diesel gensets available, but for the price, a Kubota can't be beat, though a bit noisy, so build an insulated shed, the neighbors will appreciate it.
I have two, one has already rolled over its meter at 10,000 hours. A gasoline generator, even well maintained will only get you 2500 hrs, if you're lucky. There are exceptions, but diesel is a buck less a gallon, so do the math.

The Lowboy by itself is about $5900,0 You do all the labor and make it so you can manually kill the grid and powerup the Genset manually.
Electrician will cost around 8K to 14K$ when done relay disconnect can be expensive, with a grid auto start/disconnect (county/state rules dependent).. Otherwise, I'll assume this could be a long term living situation.
You can ignore the following if it's just a part time thing.

A couple of questions. Is this located where your neighbors won't complain, and can you add to it as needed without issue?
Do you have propane, can you get another connection, or a stand alone 500 gallon tank or bigger? You will need a backup generator, and it will need to be diesel.
Are you on a restricted budget? All of this is important because it depends on how comfortable you will be in the end.

If you're limited, you will have a lot to give up, if you have say, 65K$, we can work within that comfortably.
Also climate is important, so based on the foliage, I assume somewhere South around South Carolina, Texas? This will help immensely. Sun exposure, days of sun etc.

But the bottom line is, there's no cheap solution to going totally off grid.
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Grammy

Okay, here's how dumb I am...  I was thinking just slap some solar panels on the roof and blammo! you've got power!  :woot:

Eventually, some day, I guess we'd like to go permanent with something but, for now, while we're just learning, we were thinking of just having this one be able to function in a blackout.  I know people will ask why we wouldn't just fire up a gas generator to get us through a few hours, and we could... but while we were talking about it, we started wondering out loud if solar panels could actually create enough electricity to bring power to the little cabin.  But you're telling me that solar panels must be used in conjunction with generators, is that right?  This really is "solar panels 101"!  :laugh:

(The good thing is that my husband is an electrician, so we'll save money there.) 
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Solar

Quote from: Grammy on December 27, 2022, 07:24:24 AM@Solar I'm sorry I've not been on for a while.  (We've been attending funerals.)

We have a little tiny house (cabin) in our backyard and we're interested in having it be completely able to function in the event of a power outage.  I'll put a photo of it on this post.  It's a 12x28 building with a full bath and kitchen.  Appliances, etc, include a 9000 BTU mini-split unit, half-fridge, small water heater, microwave, smart TV, coffee maker, toaster and single electric burner.  Right now, it has its own electric panel and draws from our house's lines. 

We've never learned the first thing about solar panels, generators, etc., and don't even know where to start.  I was wondering if panels could be put on the roof, since there are no trees overhanging it? 

All that to say that I'm basically asking how we would get started equipping this little unit to be able to sustain its own power?  (No rush to get to this.  I'll just peek in from time to time.) 

Hope you and Toy had a wonderful Christmas.  :smile:


First, you have to have good Southern exposure, that's a must or solar is worthless. Second, how long will you be staying in it any given time?
I ask because the battery bank needs to be sized to fit your needs, whether it's two days, or 12, and the longer you stay in it, the more batteries and the bank size, batteries may need additional in put power, (dependent on type of battery, lead acid or lithium type).

There is a lot to consider before you even consider solar.
Always start with the biggest battery bank you can afford, then match the solar array to their needs, because once you buy batteries, it's best to buy all you need upfront, you don't want old batteries with new, they cycle differently with age.
Lead acid in particular, must be the same age, like flashlight batteries, you don't add new batteries to old.
Lithium iron phosphate might be a good choice, they have a good ten year life, lead acid, 7 years. Lithium Iron Phosphate can cycle to zero without damage, (brand dependent)
Lead acid on the other hand are good from anywhere from 100 cycles, to 300?

A cycle is how low you drain the battery, below 70% on lead acid is one cycle, you don't want to do this often, you want them staying above 70% and that's hard, again, drain to zero and it could takes days to bring it up to full. Think diesel as support.

But you only have a few months to add more batteries so they keep the same level, otherwise the older batteries will drain the newer ones, equalizing the system to the level of the older batteries.

Just like the flashlight analogy, you don't add a new battery to old ones, the old ones will make the new one act like the old, because they'll suck it down to their charge level.

This is why I suggested a diesel generator, and why I need to know your budget. Also, the electric appliance/hot plate will need to be trashed, with the exception of the minisplit. Propane appliances will save you thousands on a system right up front.
But again, you really should consider a genset to offset for when there's no sun.

Budget? If you have 100 grand to work with, life will be easy, but if your budget is 20 grand, you will have to sacrifice.
If it's less, then forget  solar and start with the most batteries you can afford, and a diesel genset.
Then, over time you can add solar as your budget allows.

Oh, and if you get solar, don't let anyone flat mount your panels to the roof, they need to be able to dissipate heat, if they don't, they'll be useless after a decade. Also, only get mono crystal cut cells and avoid cheap Chinese crap.
I can go into detail if you need.

But to get started, buy a good diesel, and grow from there.

Hope this helps. Feel free to ask any questions, there is no such thing as a dumb question when you're spending money.
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Solar

Quote from: Grammy on December 27, 2022, 03:36:51 PMOkay, here's how dumb I am...  I was thinking just slap some solar panels on the roof and blammo! you've got power!  :woot:

Eventually, some day, I guess we'd like to go permanent with something but, for now, while we're just learning, we were thinking of just having this one be able to function in a blackout.  I know people will ask why we wouldn't just fire up a gas generator to get us through a few hours, and we could... but while we were talking about it, we started wondering out loud if solar panels could actually create enough electricity to bring power to the little cabin.  But you're telling me that solar panels must be used in conjunction with generators, is that right?  This really is "solar panels 101"!  :laugh:

(The good thing is that my husband is an electrician, so we'll save money there.) 
OK, I see.
No, solar panels are DC output, so you need the battery bank to store the power, then an AC inverter/charger to turn it into AC.
I say "inverter/charger" because if it's cloudy or night, the inverter can charge the battery bank when the generator is running.
Or, if you run power from the house, the power runs through the inverter/charger and keeps your batteries topped off.

There's no cheap solution when it comes to technology.

I like the Ames brand Inverters, great support, and pretty good quality at an affordable price.

Here's the one I use, but since I've been off the grid for over three decades, I started with a 12 volt DC system, 48 VDC is better when it comes to long wire runs.
Get ready for a deep dive into the world of DC current/voltage. :laugh:



https://www.aimscorp.net/3000-watt-pure-sine-inverter-charger-with-50-amp-bypass-240v.html
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Rick

I use to rebuild lead acid fork lift battery's, Can solar power battery's be rebuilt?
I dream of the day a chicken can cross the road with out it's motives being questioned.

Solar

Quote from: Rick on December 28, 2022, 08:45:55 AMI use to rebuild lead acid fork lift battery's, Can solar power battery's be rebuilt?
`
Good question...
The fork lift battery is an excellent battery for solar. I am currently using railroad communication batteries with a 20 year life.
On todays standard, they are outdated because they require a lot more current to charge.

I'll assume you're referring to the lithium Iron Phosphate, so yes, but at this point the battery is relatively knew to offgrid use, that most are still online and in service.

The early lithium offgrid batteries were literally a bunch of double AA Lithium flashlight batteries stacked in a cube, pretty expensive and labor intensive to rebuild, but you could buy off the shelf double AA's to rebuild them.

Battery tech is changing rapidly, so in a decade, instead of rebuilding a LI battery bank, you'll simply replace them with the latest tech, more efficient, at a cheaper cost.

Did that answer your question?
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Rick

Have not had a whole lot of luck with lithium , give me old school lead acid.
I dream of the day a chicken can cross the road with out it's motives being questioned.

Solar

Quote from: Rick on December 28, 2022, 02:39:09 PMHave not had a whole lot of luck with lithium , give me old school lead acid.
I know exactly what you mean! I've actually replaced Li with good old reliable NiCad batteries.
Li can be expensive and the chips they put in the batteries prematurely fail, making the entire battery a brick.
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Grammy

Well, I read your posts to him and he's off in search of a Kubota, ha!  He's taking your advice, generators, converters and battery packs first.   :wink:
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Quote from: Grammy on December 29, 2022, 08:44:42 AMWell, I read your posts to him and he's off in search of a Kubota, ha!  He's taking your advice, generators, converters and battery packs first.  :wink:
Excellent!!! :thumbup:
You're on the road to building a healthy system.

Oh, almost forgot, you can get a remote start for the Kubota, a bit pricy, but it allows you to start the Genset from inside the house, This is great for those rainy mornings when all you want is a cup of coffee. Nothing worse than making  coffee, then having to run out and kill the Gen. This is important time sitting and enjoying your first cup. :biggrin:

Also, you'll save a lot in fuel because you let it run longer than it should. There are also auto start features in the event the batteries get low and you're away, it will charge them and shut off automatically.
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rp5x5

Interesting reading this thread.

Living in a Suburban area, I wonder how one would one deal with the noise of a generator?

How much a year is spent on Diesel Fuel?  I saw a 2.4 liter per hour,  when I google it.  Is this used mostly as a backup?

What about solar system arrays for the back yard instead of the roof?




Solar

Quote from: rp5x5 on February 14, 2023, 12:07:48 PMInteresting reading this thread.

Living in a Suburban area, I wonder how one would one deal with the noise of a generator?

How much a year is spent on Diesel Fuel?  I saw a 2.4 liter per hour,  when I google it.  Is this used mostly as a backup?

What about solar system arrays for the back yard instead of the roof?




All good questions.
For a small backup genset, Cummins Onan 5K model, drinks very little diesel, about a gallon over 5 hours, 2.5 liters per hr is a bit expensive.
They're used primarily in RV's because they're so quiet. They have a 8K unit, quiet as well, but drinks a lot more diesel.
Though you may still need to make a sound barrier if it's real close to a neighbor, they do purr a bit.

Solar is best mounted on the roof for best sun exposure, backyards tend to have too many trees.
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