Advice on off grid cabin setup.

[Johnnysunrise]

I recently bought a small remote cabin with another family and have been working on replacing the aging solar power system. Initially it had a Xantrex inverter that was very much failing and I could no longer get parts for, a 1kW wind turbine system that also was the solar charge controller but the bearings on the turbine were shot and it would no longer work at low wind speeds, 2x 250W panels in one string and 4x 80W panels in a second string, as well two AC-DC shop power adapters being used to charge the batteries from generator, all tied into 3 strings of 4x6V 225aH lead acid batteries.

I have since replaced the inverter, wind power, and panels with

• Growatt SPF 3000LVM 24V - Max 2000W solar panels
• 4x 395W Q.Cell panels in two strings of two - Total 1580W, I believe it works out to roughly 74W @ 21a
• Raspberry Pi running Solar-Assistant connected to the batteries via 24V-5V buck converter pulling data from the Growatt
• In the process of swapping out the battery banks with a single Volthium 24V 200aH self heating lithium battery

Basically I believe my power needs are fairly small. Low power fridge (60W), compost toilet fan (30W), Raspberry Pi (5W), and the inverter drawing about 30W are the only things we would be running overnight, with RV water pump, laptops, and phone charging being used intermittently during the day. For the most part it is a weekend only cabin, so during the week in theory it would have a steady 100W draw, but charging as long as the sun it shining.

Basically, think it makes sense, but I will be honest until last year I didn't know anything about solar and I am second guessing everything.

Is there anything that jumps out as glaringly wrong about my setup? Do I have enough solar panels to charge my battery? Would I be better off wiring my panels different?

I attached the data sheets for all the bits for additional info.

Any feedback would be appreciated. Thanks.

 

[E. Cho]

From reading your description on my phone it all sounds pretty good. You will have enough solar for battery charging in the right full sun, correct panel angle and warm enough conditions. But solar panel output can drop to only 5-10% on overcast days, in which case your panels might only produce 50-150 watts during that time. Same if you get shading or a poor panel angle.

Next, I did not see how many watts the self heating batteries use or when and for how long they will heat. Is the battery in a well insulated box during cold periods. How warm will they keep the batteries at different temperatures? Could the battery heating drain the battery in poor solar, short daylight periods and cold conditions requiring long periods of battery heating? How long would you be away?

So maybe increase the # of panels if you can to help a bit on short winter overcast days, as at present, you are only paneled close enough for the present 24 hour loads but maybe not including the battery heating?

 

[Johnnysunrise]

From reading your description on my phone it all sounds pretty good. You will have enough solar for battery charging in the right full sun, correct panel angle and warm enough conditions. But solar panel output can drop to only 5-10% on overcast days, in which case your panels might only produce 50-150 watts during that time. Same if you get shading or a poor panel angle.

Next, I did not see how many watts the self heating batteries use or when and for how long they will heat. Is the battery in a well insulated box during cold periods. How warm will they keep the batteries at different temperatures? Could the battery heating drain the battery in poor solar, short daylight periods and cold conditions requiring long periods of battery heating? How long would you be away?

So maybe increase the # of panels if you can to help a bit on short winter overcast days, as at present, you are only paneled close enough for the present 24 hour loads but maybe not including the battery heating?

Thanks, good to know I am on the right track. I could reuse the 2 old 270W panels in a seperate string, bringing the overall efficiency of the system down a bit, but total power up to about 1800W instead of 1560W.

The battery heating is an extra feature that we probably won't actually need, since we can't really get to the cottage in the winter and will likely bring the battery out in the fall and store at home.

 

[Madcodger]

If you have 100W running continuously, that's 2400 Wh/day, or just about what your 1 battery can store. I'd put in a couple of additional batteries.

 

[efficientPV]

I think camps are a special category and people want to turn them into a full blown system. Run everything you can on 12V. lighting is all you need at night. Why are you running an inverter at night? My inverter only turns on when the fridge is needed. Like someone said, that takes a whole battery just for idle. Here is an example of what could be done. I live at my camp for 5 months. It has hot water, refrigeration, dishwasher, clothes washer, TV, lighting and some medical equipment to keep me alive at night. The clothes washer even has its own 40 gallon hot water tank. All that ran on a car battery till the end of last year when it was starting to fail, I added a 50AH lithium battery to the mix till I got home. I'm high in hog heaven now. Far cheaper than trying to get my wife to turn things off. And I probably spent a third of what you are going to spend. Spend money on panels, not batteries. I run things which can be put off for when the sun shines.

 

[RV8R]

If it were me, I would create a load energy spreadsheet “estimate” to get an idea of the different scenarios assumed energy consumption (If you do not already have that data).

We have a small cabin & typically power it by Solar almost 100% of the time. Our typical energy consumption is 500Wh to 1000Wh per 24 hr period.




All 12vdc; Fridge, Propane Furnace, LED Lights, water pump, composting toilet ( 80Wh per day ), phone & tablet chargers

Pretty light loads. 250Ah AGMs

 

[Nan_wpg]

First of all (not Solar related)…. Do not own a cabin with anyone other than yourself. Ever. Seriously. Just don’t.

how “remote” are you? How accessible is the property?

switch fridge to propane.
get a “better” inverter (idle consumption)
ditch the compost toilet. They don’t work in Canada. They are a pain. Dig an outhouse, or propane toilet.

did I mention not to own a cabin with anyone?

 

[Johnnysunrise]

Yeah, I went into it full well knowing that the biggest challenge will likely be the dynamics of co-owning the property.

Remote is relative. An hour drive from home, and then short boat ride to the cottage on an island. Because it is an island, the hope is to limit how much stuff we haul on and off the island, which is why we hope to use the low power fridge instead of hauling propane tanks. Although we mostly cook on propane. The island only has two cottages on it, with friends owning the other cottage and have had a composting toilet for about 8 years without a problem. We only use the cottage in the summer, Canadian winter isn't an issue for the composting toilets.

I bought the Growatt basically for simplicity and after reading a few good reviews, but if there are any suggestions on a better option I am all ears. The system ran all last summer without any problems, and was only this year that the old lead acid batteries started to fail and I am trying to swap out the big lead acid banks with the single 5kWh lithium.

I have been using Solar-Assistant to monitor my solar power generation and battery use, and on average my daily solar power produced is greater than my daily load, so other than the odd cloudy day I am running everything off solar, with excess charging the batteries during the day. The inverter is a relatively big draw to run all the time, but basically it comes down to keeping the fridge running 24/7. Between the two families we are pretty much up at the cottage at least very weekend, so pretty much from when we open up in the spring until shutdown in the fall we keep the fridge fairly stocked with stuff so we aren't taking a load of food in and out every time we go.

 

[RV8R]

Our current cabin fridge ARB 50Q is a 12vdc. They spec it @ an average of 0.87 amps ,,, so about 21Ah per 24 hour period.

We will be replacing it with another 12vdc fridge. That new fridge will probably use twice the energy as the ARB fridge.

If Inunderstand correctly, the only reason you need an inverter is for your 120vac fridge ?

I figure if I installed an inverter ( we do not have an inverter installed yet ), the standby & inefficiency will be about 500 Wh per day or about 200% of our ARB Fridge.

12vdc fridges are expensive, but if that allows you to turn off your inverter then it might be worth it.

 

[DIYrich]

Since you don't want to risk loosing power for the fridge, size the battery to power the fridge and inverter for 3 days (rule of thumb for off-grid).

Then panels to recharge the batteries in 1 or 2 days.

Then compare that to what you need to run everything when you are there.

Consider induction burner to reduce propane for cooking.

 

[RV8R]

I have a Van & a Cabin that both run on 12vdc, no inverter, & Propane.

A 20lb propane tank holds as much energy as 116 100 Ah lithium batteries.

So if Ya got Sun & no problems harvesting it then you can ditch the propane, but keep in mind that if you delete propane out of your system you need 116 full cycles of a 100Ah battery.

We get our 20lb size tanks filled for about $15 CAN.

What does 116 full cycles cost in “life” out of a 100Ah lithium ?

Batteries are just a “energy storage tank” that has to be replaced after a limited amount of use ,,, just like a $40 propane tank has to be replaced after 10 years.

We get by with minimal 12vdc use because we have propane. Look @ the RV Industry & how many are fully electric & no propane.

I don’t like propane fridges as I think the 12vdc are very efficient & can be generally be supplied energy by solar. Not cheap, but reduces the inverter need / energy required ,,, standby & efficiency.

All uses & situations are different, so the OP needs to sort that out & the best way to do that is via knowledge ,,, knowing a 20lb tank = 116 batteries might be a gem of info to help make the decision.

 

[E. Cho]

I have a Van & a Cabin that both run on 12vdc, no inverter, & Propane.

A 20lb propane tank holds as much energy as 116 100 Ah lithium batteries.

So if Ya got Sun & no problems harvesting it then you can ditch the propane, but keep in mind that if you delete propane out of your system you need 116 full cycles of a 100Ah battery.

We get our 20lb size tanks filled for about $15 CAN.

What does 116 full cycles cost in “life” out of a 100Ah lithium ?

Batteries are just a “energy storage tank” that has to be replaced after a limited amount of use ,,, just like a $40 propane tank has to be replaced after 10 years.

We get by with minimal 12vdc use because we have propane. Look @ the RV Industry & how many are fully electric & no propane.

I don’t like propane fridges as I think the 12vdc are very efficient & can be generally be supplied energy by solar. Not cheap, but reduces the inverter need / energy required ,,, standby & efficiency.

All uses & situations are different, so the OP needs to sort that out & the best way to do that is via knowledge ,,, knowing a 20lb tank = 116 batteries might be a gem of info to help make the decision.

I ditched propane 2 years ago. NEVER have I once missed it. Propane in my remote rural area was a HUGE F'ing PITA to get, expensive as hell to buy or to get delivered, to rent a tank, and to use. To get a "$15" bottle of propane I'd have to travel 300 miles round trip to the nearest city with a Costco. As a senior, I grew tired of filling, storing, lifting, moving, 30 and 100 lb bottles of propane on my trips to the city, which I tried to do as infrequently as possible. A propane fridge was the worst too expensive appliance that I have made and a PITA to maintain and disgusting to exhaust indoors.

With just 2.2 Kw of solar and a 100 Ahr/2.5Kw battery on a 24V system, my daily living is clean, EASY as F and have zero problems in the Canadian North. I don't have a need for immediate use of 116 full cycles of 100 Ah Lithium as you compare propane to, as to do 116 cycles would take me .... years? of solar. My battery "cycles" maybe once a month, as even in the dark days of winter I just need a few hours of sun to top up my battery. So your comparison is quite an exaggeration to at least my real world solar use and expense. It is not even remotely comparable, as so far, I at least, get daylight and or sunshine every 24 hours for 4-10 hours per day. If it were really dark for days, which it has, then I can "top up" my Lithium battery with a gasoline or diesel generator, and not 116 Ahrs worth.

Given your comparison, what happens when one runs out of propane and doesn't have easy or affordable access to that $15 CDN, 20 lb limiting bottle of toxic propane? (It would be $30+ dollars CDN for 20 lbs from the nearest propane outlet in rural BC).

Propane and or gasoline or diesel has it's place for some situations but if one can afford the initial outlay of solar, then propane is not needed. But some Off Gridders refuse to live simpler and want to simply waste energy too.

 

[RV8R]

I ditched propane 2 years ago. NEVER have I once missed it. Propane in my remote rural area was a HUGE F'ing PITA to get, expensive as hell to buy or to get delivered, to rent a tank, and to use. To get a "$15" bottle of propane I'd have to travel 300 miles round trip to the nearest city with a Costco. As a senior, I grew tired of filling, storing, lifting, moving, 30 and 100 lb bottles of propane on my trips to the city, which I tried to do as infrequently as possible. A propane fridge was the worst too expensive appliance that I have made and a PITA to maintain and disgusting to exhaust indoors.

With just 2.2 Kw of solar and a 100 Ahr/2.5Kw battery on a 24V system, my daily living is clean, EASY as F and have zero problems in the Canadian North. I don't have a need for immediate use of 116 full cycles of 100 Ah Lithium as you compare propane to, as to do 116 cycles would take me .... years? of solar. My battery "cycles" maybe once a month, as even in the dark days of winter I just need a few hours of sun to top up my battery. So your comparison is quite an exaggeration to at least my real world solar use and expense. It is not even remotely comparable, as so far, I at least, get daylight and or sunshine every 24 hours for 4-10 hours per day. If it were really dark for days, which it has, then I can "top up" my Lithium battery with a gasoline or diesel generator, and not 116 Ahrs worth.

Given your comparison, what happens when one runs out of propane and doesn't have easy or affordable access to that $15 CDN, 20 lb limiting bottle of toxic propane? (It would be $30+ dollars CDN for 20 lbs from the nearest propane outlet in rural BC).

Propane and or gasoline or diesel has it's place for some situations but if one can afford the initial outlay of solar, then propane is not needed. But some Off Gridders refuse to live simpler and want to simply waste energy too.

Knowledge is King & I understand why you made your choices ,,, well explained.




In my case, Propane is Easy & one trip (15 kms) to get my tanks filled lasts me more than a year in my cabin.

In my Van, propane is also very easy & allows us to boondock for days on a 250Ah AGM battery bank.


The OP has to figure it out for their situation/use. “All Things Heat” take a ton of energy & if that can be achieved by Solar ,,, Great ?. If the Sun ain’t shining then what ? It is my experience DIYers then turn to Propane / Gasoline / Diesel

 

[mvonw]

It ain't remote if you have cell service..

 

[RV8R]

It ain't remote if you have cell service..

I have cell service, but I had to clean out / “dredge” out my moat ,,, Do you then consider my Cabin

“ReMoat” ??

 

[E. Cho]

“ If the Sun ain’t shining then what ? It is my experience DIYers then turn to Propane / Gasoline / Diesel ."

If the sun ain't shining I use my 100 Ahr LiFePO4 battery to run my 24V to 120 AC small home until the sun / daylight starts again in the morning. Yes heating with anything is costly, but I don't always need to heat water unless the sun is shining, which it nearly always does around 11-13:00, even on overcast days. Or I just go without that day, or heat a kettle vs my hot water tank.

The exact same warning can be said about running out of Propane/Gasoline/Diesel, which I have done many many many times over the years and has often been a huge PITA to refill, unlike getting solar to effortlessly refill my LiFePO4 battery in the morning..

I quit propane before I had solar and knew of propane's toxicity, exactly because of one day running out of propane and a) to get propane delivered required a minimum of $450 purchase, 6 years ago, or b) do a 300 mile round trip to Costco to fill a 100 lb tank or c) pay double the cost of propane at nearest village supplier. I opted to cancel my propane contract and get the tank rental removed and to go to Costco but I also then started learning about and researching solar.

At least with solar, I know for sure that there will be daylight in the morning to top up / fill my Lithium fuel requirements. And solar is reliable, cheap, clean and safe, once it is set up. Propane also has costs as do fossil fuel generators, including machine purchase, maintenance, fuel, noise, smell, health, etc..

I have yet to run out of Solar and at night I use my 100 Ahr LiFePO4 battery, which also has not yet run out of energy unlike the propane/gasoline or diesel.

 

[Craig]

“ If the Sun ain’t shining then what ? It is my experience DIYers then turn to Propane / Gasoline / Diesel ."

If the sun ain't shining I use my 100 Ahr LiFePO4 battery to run my 24V to 120 AC small home until the sun / daylight starts again in the morning.

The exact same warning can be said about running out of Propane/Gasoline/Diesel, which I have done many many many times over the years and has often been a huge PITA to refill, unlike getting solar to effortlessly refill my LiFePO4 battery in the morning..

I quit propane before I ha solar and knew of propane's toxicity, exactly because of one day running out of propane and a) to get propane delivered required a minimum of $450 purchase, 6 years ago, or b) do a 300 mile round trip to Costco to fill a 100 lb tank or c) pay double the cost of propane at nearest village supplier. I opted to cancel my propane contract and get the tank rental removed and to go to Costco but I also then started learning about and researching solar.

At least with solar, I know for sure that there will be daylight in the morning to top up / fill my fuel requirements. And solar is reliable, cheap, clean and safe once it is set up. Propane also has costs as do fossil fuel generators, including machine purchase, maintenance, fuel, noise, smell, health, etc.. I have yet to run out of Solar and at night I use my 100 Ahr LiFePO4 battery, which also has not yet run out of energy unlike the propane/gasoline or diesel.

Agreed! Even though I sometimes need to augment with a generator. The thing is in a SHTF Mad Max situation propane and gas will probably be unavailable so having solar system is far superior to fossil fuels in the long run regardless of politics and environmental reasons. While using gasoline or propane is usually an easy button there is nothing wrong with striving to be completely independent even if it takes a few years and a few more dollars.

 

[mvonw]

I have cell service, but I had to clean out / “dredge” out my moat ,,, Do you then consider my Cabin

“ReMoat” ??

Bwahahaha … I wish I had a moat. And and drawbridge.

 

[RV8R]

“ If the Sun ain’t shining then what ? It is my experience DIYers then turn to Propane / Gasoline / Diesel ."

If the sun ain't shining I use my 100 Ahr LiFePO4 battery to run my 24V to 120 AC small home until the sun / daylight starts again in the morning. Yes heating with anything is costly, but I don't always need to heat water unless the sun is shining, which it nearly always does around 11-13:00, even on overcast days. Or I just go without that day, or heat a kettle vs my hot water tank.

The exact same warning can be said about running out of Propane/Gasoline/Diesel, which I have done many many many times over the years and has often been a huge PITA to refill, unlike getting solar to effortlessly refill my LiFePO4 battery in the morning..

I quit propane before I had solar and knew of propane's toxicity, exactly because of one day running out of propane and a) to get propane delivered required a minimum of $450 purchase, 6 years ago, or b) do a 300 mile round trip to Costco to fill a 100 lb tank or c) pay double the cost of propane at nearest village supplier. I opted to cancel my propane contract and get the tank rental removed and to go to Costco but I also then started learning about and researching solar.

At least with solar, I know for sure that there will be daylight in the morning to top up / fill my Lithium fuel requirements. And solar is reliable, cheap, clean and safe, once it is set up. Propane also has costs as do fossil fuel generators, including machine purchase, maintenance, fuel, noise, smell, health, etc..

I have yet to run out of Solar and at night I use my 100 Ahr LiFePO4 battery, which also has not yet run out of energy unlike the propane/gasoline or diesel.

Yup ,,, In Life you have to “Pick Your Poison”

I get it ,,, You do not like Propane & prefer to use diesel or gasoline to “top up” you Lithium.




BTW “energy is energy” & using it with efficiency in mind is using it.

So if 116 cycles would take you years ,,, wouldn’t 20lbs also take you years ,,, I do not understand your math.

I also live in BC & the sun does not shine daily guaranteed, so I supplement my 600W array with gasoline if need to ( I rarely need to as my 12vdc use is quite minimal - but that is due to my propane on hand ).

 

[RV8R]

Agreed! Even though I sometimes need to augment with a generator. The thing is in a SHTF Mad Max situation propane and gas will probably be unavailable so having solar system is far superior to fossil fuels in the long run regardless of politics and environmental reasons. While using gasoline or propane is usually an easy button there is nothing wrong with striving to be completely independent even if it takes a few years and a few more dollars.

No Man is an Island

SHTF Scenario & Humans ??

We Homo Sapiens have lived in society, industry, & science for so long we are not self sufficient & Solar won’t save your life long term. What I mean by that is unless you have the knowledge & ability to “produce” you own solar products (including mining the raw resources), you will not be “self sufficient” long term. To think otherwise is pandering to ego.

SHTF Times ,,, We need each other even more than the Good Times. Choose your “Wolf Pack” wisely.

Just my 2 cents worth opinion on SHTF.