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BigBoyKy
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# Posted: 8 Dec 2021 03:54pm
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As my introduction says I have had a smaller (10x16) hunting cabin for a few years. After what I believe is tree rats (squirrels) chewing up the t-111 siding, it’s time for a change! My plan is to go a little bigger. The smaller was fine for myself and the wife. But now I have a son and grandkids that have joined! The present setup everything is 12 volt. I do have a couple 110 volt outlets that I can hook to the generator. The closest grid is a mile away so that’s not going to happen! What I’ve done over the years is charge batteries at home and take them down. On the new I’m thinking about going solar. Basically just to not have to worry about it. I’m not sure what load I will end up with just yet, so I’m thinking 300watt worth of panels with appropriate equipment charging 2 or more batteries. Haven’t decided to put an inverter in this setup yet due to the real need at this time. One of the biggest questions is what happens to the electric from panels when batteries are fully charged? And is there a reason that I can’t have more than one battery set up to charge at one time?
There’s going to be more questions but I’ll start with this!
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travellerw
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# Posted: 8 Dec 2021 04:06pm
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Quoting: BigBoyKy One of the biggest questions is what happens to the electric from panels when batteries are fully charged? And is there a reason that I can’t have more than one battery set up to charge at one time? There’s going to be more questions but I’ll start with this!
I would suggest you head over to the solar forum and start reading, and reading, and reading... You are opening a can of worms and being educated is key.
For a quick and dirty answer I will start with saying you MUST figure out your draw (in Ah or Wh). Its the only way to properly size a battery bank to ensure it doesn't fail prematurely.
As to your other questions.. When the batteries are full the controller will just switch to float (a trickle charge). Since amps are pulled (not pushed) the panels just provide enough for that trickle.
Yes, you can have more than one battery. Many solar builds use 4, 6 or 8 6V golf cart batteries hooked in series and parallel configuration (for a 12V or 24V system).
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jhp
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# Posted: 8 Dec 2021 04:24pm - Edited by: jhp
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Welcome to the forum.
Start with a load calculator, think of every device you want to power first and how long it will run. Lights, phone chargers, TV, whatever.
Plug those inputs into a calculator to tell you how much you're going to consume every day with all that running. This one seems ok - just use the calculator part you don't need to send them your information.
https://unboundsolar.com/solar-information/offgrid-calculator
Once you have the load information you can think about how big the battery bank and panels are you'll need to support it:
https://www.altestore.com/store/calculators/off_grid_calculator/
Most people when they get to this point start looking for feedback on their calculations based on what others have done. From there you can figure out options to piece together a system from various sources.
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gcrank1
Member
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# Posted: 8 Dec 2021 04:28pm - Edited by: gcrank1
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Questions are a Great start!
Pls, do Not buy anything until you have done the preliminary 'power audit' work, that sets the stage for the 'math'.
If your pockets arent deep dont expect you can have elec on demand for 'big' stuff like at home on grid.
This site is great: diysolarforum.com
That said, I have a 16x24 with a small system that has been working well, 600w array and currently 2x 100ah 12v bats (it can support 3 in parallel). It was good, but got better (ie, more user friendly) when I dropped the 12vdc and went straight to a pure sine wave (PSW) inverter to 120vac. All the led lights (only way to go), usb ports/chargers, tool chargers, box fans, etc/'light draw' stuff runs fine on the 300w inverter.
For big stuff I start the 1750/2000w inverter/gen. Big like a small microwave, toaster, hd 'skill saw', etc.
Ime, No matter how much power (figure it in watts) you think you 'need' you have to at least double, if not triple it for calcs! (power creep begins immediately after installation)
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BigBoyKy
Member
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# Posted: 8 Dec 2021 04:45pm
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The hardest part about this is the cabin isn’t used daily, and sometimes it sits empty for a month or longer. There’s a 2 weeks to a month during hunting season that it’s used heavily. Spring rarely anybody there. Summer maybe a weekend here and there. Fall 1 or 2 weekends a month. It’s very sporadic. The way it is now during hunting season two batteries handle the load! But that’s also having the generator for a tv to watch a game or two maybe a movie. In the current cabin only 12 volt stuff is lights and charging phones…
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jhp
Member
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# Posted: 8 Dec 2021 05:12pm - Edited by: jhp
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I tend to fall into the "buy once cry once" camp on this and would size the system as if 2 weeks a month, every month, with the same loads as hunting camp. Then you don't sink money into a system and still end up having to fire up a generator.
If your loads are relatively small, you'll be surprised at what you can get away with. Suggestion here is to be honest about what you're going to run and pad the numbers a bit for a buffer. If you think you'll have the TV on for noise for 4-5 hours at night assume it will stay on for 8-10 while you fall asleep in the chair lol.
Think about energy hogs like microwaves, coffee pots, and vacuum cleaners and if you can do something alternative like using a percolator on a gas stove. If you can't live without them think generator vs solar.
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Nobadays
Member
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# Posted: 8 Dec 2021 05:34pm
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Good advice already given!
I 100% agree with the consensus.... do an energy audit before you do/buy anything! You wouldn't buy a Smart car if you know you need to pull a 5th wheel and visa versa, you wouldn't buy a 1 ton diesel truck if you'll be pulling a teardrop trailer. Same is true for solar.... size to your load!
Do it! I help design and install solar for other cabin owners around us and getting them to da an audit is the hardest part! Gcrank1 is right, power creep happens!
Granted, it is hard to size solar for sporadic use and may not be worth it to build a system big enough to watch TV, run an microwave or any other big energy hog. A system like gcrank1 has might be a good option... my only add to that would be to possibly go with a 1500-2000 watt inverter as you/ wife/kids might pop something in the microwave or fire up a power tool and forget to use the generator. Pop goes the inverter overload!
The diy solar website has a wealth of information as well as "blueprints" of different sized systems. Do go there and read a lot!! https://diysolarforum.com/
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gcrank1
Member
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# Posted: 8 Dec 2021 06:20pm - Edited by: gcrank1
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I should add that my 'microwave, toaster, etc' is its own circuit just so the OverLoad Incident doesnt happen! The only way it is powered is when the gen runs.
Whenever the gen runs it also powers an auto-type charger to the bat banks; any amps in is Good Amps! (though most gens have 12vdc taps dont use them to charge 12v bats, not enough amps output there).
When I had my solar torn down to rebuild that is how I kept the bats up. And my 1st step when marginal is Energy Conservation. Using a Yeti clone ice chest saves a lot of watt hrs over trying to run the 4.5cf fridge.
Fwiw, if I were in your place (and I used to be) I would be strongly looking at 1 x 100ah LFP battery which will equal at least 2 x 100ah 'marine' type deep cycle bats.
2 of those LFPs would be great. They weigh like 1/2 as much so lots easier to take home to charge, are at least 80% usable watts and are supposed to last 10 or more years. If your old bats are in need of replacement now would be the time to seriously consider it.
Id do that and use a while to find out IF I even needed to put up solar.
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DaveBell
Moderator
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# Posted: 8 Dec 2021 07:14pm
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Quoting: BigBoyKy One of the biggest questions is what happens to the electric from panels when batteries are fully charged?
Electric service provides potential. It is a pull not a push. When you turn something on, it pulls current or amps. 15 amp circuit breaker, 15 amp wire, and 15 amp receptacle, supplies current up to 15 amps. More than that and the breaker trips, preventing heat and fire. So if you had a battery charge tender, it would sense a threshold of battery charge, cut on, charging the batteries, drawing electricity. When the batteries reach fully charged state, the battery tender turns off and stops drawing current. Electrify from the solar panels is constantly supplied during daytime and is only consumed if something is plugged in.
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gcrank1
Member
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# Posted: 8 Dec 2021 07:42pm
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Like, um, there is no 'flow' unless a tap is turned on?
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travellerw
Member
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# Posted: 8 Dec 2021 09:24pm - Edited by: travellerw
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Ok.. After you provided a little more information about your sporadic use.. I'm really not convinced solar is the right solution for you. It will be complex, costly and with a learning curve.
Personally I think you should look into the portable power stations and supplement that with a small generator (sounds like you already have one, but a Honda 1-2K unit would work great). Depending on the size of power station you buy, you could even do a small 100-300W solar if it tickled your fancy. Power stations come with everything built in (inverter, solar controller, 12V outlet, ect).
You would still need to do an energy audit to ensure you get a unit that is properly sized, but there is some play room. You could still carry it back and forth and charge it at home, but it would be MUCH lighter than lead acid batts. Then when you are running the generator to make toast, or coffee or whatever, you could dump some watt hours back into that station. However, the one I bought can go from dead to fully charged in 2.5 hours. So if you do use more power than you thought, you just fire up the genny and charge it back up (or again a small solar system)
A power station solution will come out cheaper and be much simpler for your kind of use!
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BigBoyKy
Member
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# Posted: 8 Dec 2021 11:16pm - Edited by: BigBoyKy
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Electric service provides potential. It is a pull not a push. When you turn something on, it pulls current or amps. 15 amp circuit breaker, 15 amp wire, and 15 amp receptacle, supplies current up to 15 amps. More than that and the breaker trips, preventing heat and fire. So if you had a battery charge tender, it would sense a threshold of battery charge, cut on, charging the batteries, drawing electricity. When the batteries reach fully charged state, the battery tender turns off and stops drawing current. Electrify from the solar panels is constantly supplied during daytime and is only consumed if something is plugged in.
I figured as much that question was really just wanting someone to validate something I read elsewhere that stated that charge controllers would over charge batteries and in turn kill them!
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BigBoyKy
Member
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# Posted: 8 Dec 2021 11:31pm
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I’ve got some idea of what I need to do…. Uhhhh maybe! Have more digging that’s for sure! I know electric pretty well. The solar (panels/equipment) is what I’m not sure about! But will have it figured out soon!
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ICC
Member
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# Posted: 8 Dec 2021 11:52pm
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Quoting: BigBoyKy something I read elsewhere that stated that charge controllers would over charge batteries and in turn kill them
Yeah, so much misinformation out there. It is called a charge controller because it controls the charge that goes into the batteries (when programmed correctly if it is more than a bare-bones, basic box).
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Brettny
Member
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# Posted: 9 Dec 2021 05:59am
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Quoting: BigBoyKy There’s a 2 weeks to a month during hunting season that it’s used heavily
Dont build a system for those 2 heavily used weeks. Build the system for the rest of your trips. Running a generator for a few hours a day to charge your batteries isnt the end of the world.
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gcrank1
Member
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# Posted: 9 Dec 2021 10:29am
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Energy 'audit' sorts out:
Required watts
Wanted stuff watts
Extras you shouldnt have off grid, too many watts
All that over time to provide a watt-hours use figure.
That all defines the bat-bank size in Voltage and Amp Hours plus a cushion of capacity for non-solar days.
Bats:
Old lead-acid technology, typically No More than 50% ah's usable (to make mine last I use 30%; ie, 100ah bat = 30ah usable. I can go to 50% occasionally; do it all the time and you kill the bats fairly quickly).
LFP, a good 80% of capacity usable. Expensive but the current efficiency king.
With the bat-bank chemistry and size defined you can plan the solar array required to keep it charged. Note that the panels are never going to put out what they are rated at unless you maybe live somewhere like Arizona. 70% of 'rated' is being generous.
The array must be reasonably close to the scc and bat-bank.
The array can be an 'eyesore' to the landscape you have, so I dont have mine where it 'should be'.
That in turn defines the Solar Charge Control size you need.
Then the proper gauge wires, fuses, disconnects, service box, etc to connect all up safely.
Fyi, the lower the voltage system the closer all the components need to be to avoid line losses and/or huge wiring expenses.
And, so ya know, there is a tipping point where it makes a lot of sense to change from 12v to 24v, or even 48v.
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BigBoyKy
Member
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# Posted: 10 Dec 2021 11:19pm
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So after some deliberation I think I’m going to skip the solar in the beginning of this new cabin. Going to check out a portable power station. Solar may come back in the future…. Basically see how much load I’m really going to need.
So to stray away from that part I’ve read to use peppermint oil on the siding to keep the critters away, does that work? Oldest son suggested metal siding but I like the appearance of wood siding, just don’t want to rebuild it in 8-10 years. What’s the thought here?
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kevlar
Member
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# Posted: 10 Dec 2021 11:26pm
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Metal is certainly the best for critters and longevity, but agree that it doesn't add character like wood. Have you thought about putting hardware cloth under the wood? It's not cheap but what really is anymore? Have heard 1/4 inch will keep mice out. I'm using it under the floor of mine to keep mice and such out of the insulation, and considering doing the corners and any areas that seem to be prone to squirrels and such getting into. Just a thought.
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gcrank1
Member
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# Posted: 10 Dec 2021 11:57pm - Edited by: gcrank1
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Ive had wood on my '83-'84 build, in a mixed woods with critters, still in good shape last I saw it a year ago. We were careful on fitting it together, eventually had some mice but they were fairly easy to keep under control with our use pattern. Siding was barn boards from an 1897 barn, classic red barn paint.
Current 10yr old cabin is situated similar, not my build, prev owner/builder left gaps about everywhere. We have mice and pine squirrel issues.... Ive been pulling siding boards off and blocking holes 
The sawmill roughcut board siding is fine, no finish at all.
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Brettny
Member
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# Posted: 11 Dec 2021 08:01am
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I have t111 siding on a garage built about 20yrs ago. The horizontal joint had been rotted about 8in for 10yrs(when I bought it). It had Z flashing. The carpenter bees and the wood packers love it. The paint on it has looked like crap the 10yrs I have owned it.
With that being said I'm going to use wood (real wood) siding in my covered porch. It's well protected and shouldnt see much sun. The rest will most likely be vinyl or metal siding. I want to enjoy our cabin, not have to do much of any maintenance just for a look.
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Nobadays
Member
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# Posted: 11 Dec 2021 11:30am
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Quoting: BigBoyKy Oldest son suggested metal siding but I like the appearance of wood siding,
You might check with a local metal company, a cabin built in our area last year used metal siding... similar to metal roofing but rolled to look kind of like lap siding and it had a wood grain print on it.... no idea of the cost.
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