A newbie, a beautiful old off grid cabin, COLD wintertime temps and needing some SOLAR power

Greetings, I’m brand new to the forum; I’m very electrically challenged, but I’m learning…. I’ve really enjoyed watching videos from Will and others, and appreciate the education I’m getting.

In 2018 I purchased an old cabin that was about to be destroyed to make way for a new hotel in Island Park, Idaho, not far from Yellowstone National Park. I had it moved and put on a new foundation on my property about 8 miles from where it was born. I’ve been slowly working its rehab ever since. Summer temps are warm and wonderful but winters are COLD. -20F is typical, -40F is not uncommon and -60F (coldest in Idaho history) was recorded less than 6 miles from my cabin on 1/18/1943. Access is limited to snowmobile or tracked vehicles 6 months a year.

Cabin Details: 17’x36’ sitting on a 9ft tall basement, will be wood fireplace warmed, will never be insulated.
Off grid - no power to the property.
The cabin is not presently wired. I hope to wire it soon and am now leaning toward conventional 120VAC.
I have a shallow sand point well that I installed myself. To pump water I just graduated from a hand pump to a rebuilt 1926 Duro Piston Pump that I have been powering with either the original 120VAC motor (generator) or a 12V/24V DC motor (battery). I built and permitted an outhouse. The wife and her lady friends like it. When I have solar power, I will get internet access.

Use: Summertime could be 3-4 days at a time with a week of recharging in between. Winter will be several overnights a season, typically a single overnight, but never more than 2.

The important details: My first cut at a stingy energy need calc was 2350W (summer) and 1500 (winter). With 5 & 3 summer & winter peak sun hours respectively, I got a 540W summer and 350W needs (minimum). Because of the decreasing cost of panels, I’m thinking I’de like 1000-1200 Watts +/- of panels.

By far the best place to site my solar array will be 115’ south of the cabin. So the distance from the solar panels to my basement battery and power management location will be 130ft.

Because of the distance to panels, I’m leaning toward a 24V system (48V scares me).

I’m also leaning toward an “All-in-one” Charger/Inverter system, and am open to any battery type, but I know the extreme cold may be a controlling factor for both the power management system and batteries.

My basement is 9 ft tall, but only about 5.5 ft below grade. I know I get warmth from the ground and a insulation from the surrounding snow, but I’m making an assumption that I could get as cold as -5F down there at times (at present cabin is more than drafty and the floor is not insulated between the basement). If anyone had data that could refine my hopefully conservative temp guesstimate, I’d appreciate it as this really seems to exclude most all-in-one charger/inverter systems.

For the charger/inverters I like the cost and good reviews and large following of the MPP and Growatt systems but their lower operating temp is listed as 0C (32F) and this just won’t cut it (as I understand it - though I suspect I could build some kind of insulated box around it for wintertime only installation). Midnight Solar’s MN3024DIY has a better lower operating temperature limit (-15C/5F), but reviews don’t appear as good and that temp limit may not cut it. The Victron EasySolar 24/1600/40 is rated at -20C (-4F) which would probably work and seems well sized for my needs, though it’s big brother, Victron EasySolar 24/3000/70-50, is rated to -40C / -40F which is the best I’ve seen for lower temps.

Apologies about my long diatribe. Any help on selecting the charger/inverter, the battery types/size or anything including design help would be greatly appreciated. I also included a few pictures of my diamond in the rough in case you were interested, Cheers and thanks in advance,

Hopitrout

"Never will be insulated"....well if it is a fishing cabin used on a few weekends of the year, good for you. If it is a new permanent dwelling, I hope you cut firewood every day of your life. Batteries and cold just don't work. Below freezing is your enemy and will be the game changer for you. Solar is not your solution. I recommend looking at something like Geothermal, water, steam engine, or wind.
There currently are heating pad systems that keep your batteries above freezing but the consume lots of battery juice. You freeze solar stuff and you throw money into the wood stove as kindling.

MPRanger, its a get away only. Will spend a lot of summer and fall time there with little heating needed. Firewood is very close, not a problem. Winter use will just be rare overnights and I’ll stage firewood for that. The reason I’m not insulating is to keep the beautiful ceilings and roof structure as it is. Though my neighbor‘s places are insulated, most are very successful with off grid solar. I assume if I can keep lead acid batteries charged, I can use them successfully?

A fully charged lead acid battery will freeze at -70°C, which makes it one of the best batteries for low temperature operation. Unfortunately, as a lead acid battery discharges, the electrolyte acid grows weaker until at full discharge the electrolyte becomes pure water. Here's a very cool way to power stuff from your stove chimney: . I'm all about the rustic stuff.
Like tents? Try a yurt? Like farms? Try a grain bin conversion. I'm the Daniel Boone off grid type so I admire your bringing technology into the woods.

MPRanger thanks for the encouragement. I spend a lot of time sleeping outside, so love it as I’m sure you do. I hope to learn a lot bringing Solar to my cabin. I’m starting to think that when I build my final home, it will be solar as well, though grid tied, so this is all important to me. I need to focus on more conventional. Temperature is an issue. Hoping to get insight on the stuff from my original post, especially the All-in-one inverter/charger systems applicable for cold environments, etc. Cheers.

You have a few issues here that require more attention.

24V is no more or less dangerous than 48V, it's after 48V where rules & regs change along with Gear Considerations.
Systems should be designed not to exceed 250A draw from batteries, 12V@250A=3000W (120V/25A AC), 24V@250A=6000W (120V/50A AC), 48V@250A=12,000W (120V/100A AC) Divide by 2 for 240VAC Split Phase (North America).

120V / 240V. 240VAC is simply two legs of 120V. By using a double breaker you get to take from the 2 legs to output 240V otherwise any single breaker only uses one leg, in the box. I went 120V Only and I regret that choice because I imposed a limitation on myself, fortunately, I am wired to be able to use either or because I foresaw the possibility of an upgrade being required.

Solar Panels 110' distance. The size of DC Cable to run that distance would require a Mortgage ! because DC is not good for distance & would be seriously problematic. (This is why the world is AC and not DC) Thomas Eddison's DC vs Nikola Tesla's AC war, was the deciding factor.

A Common solution is to build a "Powerhouse" shed near the panels with Inverter, Batteries etc, then to run AC from there to the structure. This does not have to be big, my own Powerhouse is combined with my Pumphouse and the two sides are a total of 14'x6' (7x6 each side). Because this is dual purpose & also holds my water pressure tank, I heat it with a recovered RV Direct Vent 12V/LPG furnace and the building is hyper insulated, temp is kept at 10C/50F.

Second Common Solution is to use Microinverters that output AC Power which can be combined and sent to a central Inverter with batteries. This is NOT my area and so I cannot make appropriate suggestions. @Hedges knows this sort of stuff pretty well, so I just pinged him and hopefully he can chime in.

I am 24V with 4000W/12,000W Low Frequency Inverter, 1190AH of LFP & 428AH of Heavy Lead in two separate banks. 2kw of Solar Panel with an average of 3.5-4kwh of usage a day. (Hyper Efficient house & appliances/devices) and 100% offgrid, rural & remote, near Algonquin Park Ontario Canada. See the First Link in my Signature "About my System" for much more detail, diagrams, photo's & more.

Hope it helps, Good Luck

Steve_S said:

Solar Panels 110' distance. The size of DC Cable to run that distance would require a Mortgage ! because DC is not good for distance & would be seriously problematic. (This is why the world is AC and not DC) Thomas Eddison's DC vs Nikola Tesla's AC war, was the deciding factor.

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...it all depends on your PV series voltage and amps.. high enough PV volts (that is within your MPPT controller) you could go hundreds of feet fine (under 3% loss) with smaller wire.

In short a voltage calculator is your friend.


@Hopitrout using the link above I ran an example calculation based on 1200w array in series (4*300w panels with a open voltage of 48) for 150’ distance with a 10a supply and it calculates you would need only 10-12awg.. supporting up to 192v. Note 192v is open circuit where as when there is a ‘load’ your amps increase and volts decrease so for a more realistic Volt value on wire needs I use the reg. Volt. Value which is 40 or so which equals 160v and calls for 10awg wire. Either way not bad. All of this assumes you have a MPPT controller in the inverter that can handle this voltage like a MPP LV6548 or Growatt version.

Good luck

Hopitrout said:

Temperature is an issue. Hoping to get insight on the stuff from my original post, especially the All-in-one inverter/charger systems applicable for cold environments, etc. Cheers.

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Research seed warming mats as a battery warmer. Not sold on lead personally, my luck with longevity was crap when compared to my current system, lifepo4. Of course I am setup in a controlled environment. I have read and know of two people that have cabins in cold climates that can get down to -10f to -15f and use lifepo4 successfully.

Battery box with proper insulation and shelter (aka out of wind and moisture risk) with proper backup, if inverter fails then another mat that is DC powered in addition to a BMS that has a cold disconnect WiTH a MPPT Charger that monitors temp. And if below a certain temp via relay turns off charging. In short it can be done but you have to pay particular attention to your setup. All of the above is now standard functionality for most devices - low temp. Disconnect.

Edit - forgot since your basement is 9’ earth is your friend. I know another setup where they leveraged two sides of the walls for their battery box given it was below the frost line so roughly 40f even though the outside temp was well below zero.

Good luck

solardad said:

Research seed warming mats as a battery warmer. Not sold on lead personally, my luck with longevity was crap when compared to my current system, lifepo4. Of course I am setup in a controlled environment. I have read and know of two people that have cabins in cold climates that can get down to -10f to -15f and use lifepo4 successfully.

Battery box with proper insulation and shelter (aka out of wind and moisture risk) with proper backup, if inverter fails then another mat that is DC powered in addition to a BMS that has a cold disconnect WiTH a MPPT Charger that monitors temp. And if below a certain temp via relay turns off charging. In short it can be done but you have to pay particular attention to your setup. All of the above is now standard functionality for most devices - low temp. Disconnect.

Edit - forgot since your basement is 9’ earth is your friend. I know another setup where they leveraged two sides of the walls for their battery box given it was below the frost line so roughly 40f even though the outside temp was well below zero.

Good luck

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Solardad thanks so much for the thoughtful reply. Apologies for not replying earlier as I’ve been traveling. I know my foundation depth is a big positive to capture the heat from the earth and think you’re spot on for me to use a foundation corner. I’ll research the seed warming mats as well. Finally thanks for the calc on wire gauge - I really want to take advantage of my basement for locating my power control and battery storage areas. Having them in a separate enclosure close to the solar panels would be expensive, and would get buried in snow, likely inaaccessible all winter long.

I don’t know much about the Chinese all in one inverter systems .
I think every one makes a all in one inverter system I went with tier 1 equipment , I use out back equipment
I have a fp1 36 48volt all in one system it bolts to the wall and you hook your battery and solar panel to it and your done . 20%
Snyder makes good equipment allso .
I use 4500 watts of solar and 16 sams club 6v golf cart battery’s.
My battery sit in my garage and sees below zero every year .
I use 10% of my bank over night now , and will use 20% in 5 week

Hopitrout said:

assume if I can keep lead acid batteries charged, I can use them successfully?

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Yes. Some people view things black snd white and think everything’s an absolute

all-in-ones aren’t usually lead acid do not cold weather friendly

below grade check,
battery box heavily insulated, check out the below for insulation:


R value of 60..... it is however something you need to be careful with while using as a single puncture renders its insulating value to R10 or R11. measure you battery pack size, make a box to hold the batteries with the following items figured in.... 2" hard blue foam, the above mentioned panasonic vacuum insulated panel (1" thick model) and then roughly a 1/2" neoprene foam insulation. lay the thick blue foam as the first layer in the box, then a a layer of neoprene, then the panasonic VIP panels, then a last layer of the neoprene. The neoprene is there to protect the panasonic panels from damage, though they will add some R value as well. do this for all sides and an airtight (or as close as you can get) top cover. for the bottom you will have to rely on the 2" bule insulating foam, I would double it up, and then put an aluminum plate on top of the foam.

with the above, you could put a couple of 10-25 watt 12 volt silicone heating pads on the bottom of the aluminum and it would only take a few watts to keep the battery bank at a safe temp. Wire them in series initially till you determine the actual heat output if its insufficient then wire them in parallel. a cheap temp controller with a temp sensor can turn the heating pads off and on and/or a board that can set duty cycle can be used to cycle the heating pads off and on so they do not heat up to fast and cook the bottom of the batteries (use small enough heating pads and this is not a concern.)

a million and one ways to skin this particular goat, so don't get to worried, plenty of info on this forum to assist. I recommend reading this thread for battery heating. other links will appear in the similar threads box that will be good reading as well. while it is LFP centric, the battery heating portions will be the same.


good luck.

just my two cents, flooded lead acid need a lot of care and feeding, chances are you will destroy them in 12-18 months if lucky. There are members on this forum, and several others that have had flooded lead acid packs last them 5, 8, even 10 years in a couple of cases, but they were not their first FLA pack (they lost several and learned the tricks) and they actually lived with them either full time, or damn close to it, which allows you to mother hen the batteries. AGM's while expensive are probably your best bet initially if you choose not to go the lithium route. lithium if kept warm, or if kept in a 40-60% charge range and not charged or discharged when colder than the makers recommendation's (typically -10 to -15°C for discharge, and 5°C for charging) then they can sit in a semi discharged state in cold weather without too much issue. once again the data is staged all over this forum so with the battery box I suggested, you could easily run LiFePo4's with no issues.

once again

good luck.

LiFePO4 may be an option if disconnected and not charged in cold weather.
They can be a fire hazard if something goes wrong; rare, but we hear of it.

AGM can charge in freezing weather, or if fully charged can sit disconnected all winter.

110' to panels should be no big deal, with series connected PV panels for higher voltage. Most MPPT charge controllers are for < 150Voc, some as high as <600Voc. You do need to apply temperature adjustments for your cold location. Usually, Voc is increased above PV panel spec no more than 16%, but with your extreme cold could be a bit more.

Here's an expensive, quality inverter which is spec'd down to -25 degrees C. (That's only -13F) I'm not finding a separate storage/shipping temperature.
It can be used with either AC or DC coupling. AC coupling means using a grid-tie PV inverter.



Your place looks nice.
Maybe insulation can go on the outside when re-roofed.

ken morgan said:

just my two cents, flooded lead acid need a lot of care and feeding, chances are you will destroy them in 12-18 months if lucky. There are members on this forum, and several others that have had flooded lead acid packs last them 5, 8, even 10 years in a couple of cases, but they were not their first FLA pack (they lost several and learned the tricks) and they actually lived with them either full time, or damn close to it, which allows you to mother hen the batteries. AGM's while expensive are probably your best bet initially if you choose not to go the lithium route. lithium if kept warm, or if kept in a 40-60% charge range and not charged or discharged when colder than the makers recommendation's (typically -10 to -15°C for discharge, and 5°C for charging) then they can sit in a semi discharged state in cold weather without too much issue. once again the data is staged all over this forum so with the battery box I suggested, you could easily run LiFePo4's with no issues.

once again

good luck.

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Ken thanks for your insight and information on the battery warm box. I’m starting to lean toward a small AGM system. Then, after I gain some experience, and after winter snowmobile visits verifying my panels remain snow free and the system is working - graduating to a bigger LiFePO4 system. I’m still struggling to find the charger /controller (ideally an all-in-one) that could run in my COLD temps, and have 1) remote monitoring capability, 2) make the future inspector happy (e.g., UL listed), and 3) not break the bank.

Hopitrout said:

Ken thanks for your insight and information on the battery warm box. I’m starting to lean toward a small AGM system. Then, after I gain some experience, and after winter snowmobile visits verifying my panels remain snow free and the system is working - graduating to a bigger LiFePO4 system. I’m still struggling to find the charger /controller (ideally an all-in-one) that could run in my COLD temps, and have 1) remote monitoring capability, 2) make the future inspector happy (e.g., UL listed), and 3) not break the bank.

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Its tough making those decisions. the only thing is that every last one of us has our own preferences, so you gotta take that into account.

I prefer a decentralized system where I pick and choose from what I consider to be the best or at least top tier equipment in the different categories.

For instance, I am a big fan of the morningstar solar charge controllers. most people on this forum are not quite so fond of them. Morningstar are well known in the remote location telecom industry where the ultimate requirement is proper function (setting wise) and reliability. can't have it going down, can't have it not meeting the correct charge settings. Problem is they are expensive. As in 3-4 times the price of the cheaper tier two items, and it is at least 30% more expensive than several of the other top tier brands. To top it off it does not talk directly to any inverter, or BMS system. Not that it cannot, it is just nobody has made the effort to unravel it in that area.

I don't care, I want to buy things one time they only have to last me 15-20 years as at my current age anything past that and i will probably be wetting my bed at night and playing with myself in public spaces at the old folks home.

Inverters I am at a crossroads at the moment, I have used Magnums for years but am now investigating several other makers for my own reasons.

but once again this forum is full of info, you just need to filter through it to find out what you need. asking questions is always welcome as well though you will then have to sort through all of our prejudices in regards to equipment.

FWIW I have a 800 sq ft cabin, and a 40 x 50 shop I power all of the single phase items off of solar and while not a beginner still have loads that I can and will learn, and I am learning as I go at the moment with the lithium chemistries.

I agree with building a small insulated box for the equipment. Perhaps a basement room in its entirety.

I don't entirely agree with using the vacuum insulated panels though as they eventually leak and then become useless over several years. They're very very useful in certain applications where you need really good insulation with limited space available but it seems like you have that space to use.

You would be better served by just putting several inches of good old foam board in.

Short_Shot said:

I agree with building a small insulated box for the equipment. Perhaps a basement room in its entirety.

I don't entirely agree with using the vacuum insulated panels though as they eventually leak and then become useless over several years. They're very very useful in certain applications where you need really good insulation with limited space available but it seems like you have that space to use.

You would be better served by just putting several inches of good old foam board in.

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yeah if you are not careful it would definitely leak. but this is coming from panasonic, not china so I am sure its life span if used in its proper environment will be just as long as any other insulation panel.

Straight foam insulation board will work just need more of it... that's what I did for my battery box.

Off topic:
I just think the new insulating tech is cool as beans. Wish I could afford enough to do the entire inside of my overhead in the cabin. Standard foam panels will not fit through the overhead access without cutting them down, and the panels that panasonic is offering just will fit. The price compares when you realize that you would need to double or triple the standard foam insulation panels to get the same R rating. being you can use spray foam to install them with I was thinking about making my overhead totally air tight in the area above my drop ceiling which would save energy all around both summer and winter. I just do not have the cash ATM for the panels and the foam spray to seal them with.

ken morgan said:

yeah if you are not careful it would definitely leak. but this is coming from panasonic, not china so I am sure its life span if used in its proper environment will be just as long as any other insulation panel.

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The only reason I bring this up is not to discredit the vacuum panels. They're phenomenal and definitely work better than any other comparable weight or volume material aside from perhaps aerogel insulations. If the application calls for it absolutely use them. They're incredible for a refrigerator for example.

But the cost is much higher.

Just to make folks aware of the concerns, including handling and installation issues with may cause problems as you've stated.

Panasonic's R66 stuff claims R12 center rating after 6 decades but effective starts at R22. If the degradation is linear then effective R value may drop to R17 or less within 15 years. Still pretty damn good, honestly, but that's best case.

If you can afford 4 inches of R5 xps foam (and you can) it'll still be R20 after 10 years, or 20, or more.

At the end of the day the cost is more important in a situation like this where 1 inch of insulation vs 4 inches is almost irrelevant.

Panasonic panels are almost 8 bucks a square foot, (30 dollars for a roughly 23x22 panel on digikey right now) plus slightly higher instalation cost needing more backing studs and tape. The xps foam is 50 cents a square foot for R20 4" panels (plus tape and stuff) or about 65 dollars for a 4x8 foot sheet.

There are cheaper vacuum panels out there but of course the service life isn't as good.

Cool beans, I am just always curious about new tech and its always easier to reduce power consumption then it is to make power so I was digging around looking into these after coming across them (god knows where).