New off-grid cabin for a newbie!

medic149medic149 Registered Users Posts: 4

Hello everyone,

I’ve been looking through a lot of past posts on many of the topics I am looking for help on, but figured I would start another discussion since many of the things I found were several years old. 

We just purchased a 320 sq. ft., with loft bedroom area, totally off-grid cabin in Camden, NY.  We plan on using it probably 3-4 full weeks and 5 – 10 weekends a year, mostly spring, summer, and fall.  Probably more in 5-6 years when we retire. 

No power available.  There is a dug well which has plenty of non-drinking water (haven’t tested it yet to see if drinkable).  It has a new propane stove and wood stove, so heat and cooking won’t be a problem.  No fridge yet.  No bathroom/running water, but has an outhouse.  No wiring.

We will be placing our 29’ Jayco trailer on the property to use as well, especially until we get some power system going.  I have Honda EU2200i and EU2200ic generators to work in tandem or individually.  Been using these when camping. 

I would love to do solar, but may need to wait until we construct a pole barn type roofed structure to place the trailer under.  Thinking of placing solar panels on that roof instead of the cabin roof or on the ground. 

So, now I am thinking of maybe getting a battery bank  to store power for the cabin and use the generators to charge them until I get solar panels on the roof or even a couple on the ground to charge the battery bank when we’re not there. 

I’ve been working on my electric load analysis and have come up with the following:

Device

AC or DC

Quantity

Wattage

Hours Per Day

Days Per Week

Average Watt-hours Per Day

Maximum Watt-hours Per Day

Refrigerator

DC

1

40

24

7

960.0

960.0

Cell Booster

DC

 

 

 

 

 

 

AJ Laptop

AC

1

60

12

7

720.0

720.0

DJ Laptop

AC

1

45

6

7

270.0

270.0

Tablets

AC

2

10

12

7

240.0

240.0

Microwave

AC

1

1000

0.5

7

500.0

500.0

LED TV

AC

1

120

16

7

1920.0

1920.0

Clock Radio

AC

1

10

24

7

240.0

240.0

RV Water Pump

DC

1

100

1

7

100.0

100.0

AC

AC

1

1500

16

7

24000.0

24000.0

RV Furnace Blower

DC

1

100

2

4

114.3

200.0

LED Lights

AC

3

15

16

7

720.0

720.0

LED Lights

AC

1

9

12

7

108.0

108.0

Toaster

AC

1

1100

0.25

7

275.0

275.0

Window Fan

AC

1

150

16

7

2400.0

2400.0

Sub Totals

AVERAGE

MAXIMUM

32653.0

32653.0

 

The AC of course takes the most energy and hopefully would not be used much, if at all the first year, but have to add it in.  We could even just run that off of the generator on its own when needed until such time we have a large enough battery bank and solar system in-place.  Also would look at eventually using an outdoor tank less hot water heater using propane. 

So, knowing this information, is it feasible to start building my battery bank now and use the generator to charge it and for times of high demand power?  If so, what batteries should I aim to purchase?  What inverter? And, what else?    I am a newbie!!

Thanks in advance for your help!

AJ


Comments

  • littleharbor2littleharbor2 Solar Expert Posts: 1,694 ✭✭✭✭
    edited November 2020 #2
    Not recommended to let flooded batteries sit without some form of maintenance charging source. They have fairly rapid self discharge. AGM batteries would work better there but are pretty costly.  Maybe a small battery bank which you could take with you at least in the winter till you get solar installed.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭
    It looks like your numbers are very high to me .
     My cabin is 2800 sq feet and it will run on 2/300 watts with every thing running all day and 200 watts at night 
     I don’t even try to conserve power . 
     My place stays at 67o all summer  you probably won’t need much AC 
     you really need some solar or you will need to run the genarator a lot . 
     11/2 to 2 hours a day and maybe 6 hours once or twice a week . 
     A charge controller and 900 watts of solar panel is a game changer . 
      If you have any sun 😜. 
      At my place the sun gets turned off the day after thanks giving and it gets very dark till mid January . 
      Plus it snows every day till may .
     Im just south of   Oneonta down rout 28  . So about 2 hours away . 
       You can’t really start buying stuff because you need a complete system designed to power your loads 
      Your battery’s should be all the same age size and lot number . 
      Your inverter need to be sized to the loads the battery’s feed the loads the solar panels charge the battery’s . 
      It’s winter now and you will be buried in snow soon so I would not buy battery’s now . 
       You could just run off one of your little Honda’s for now . 
        I use a flex power one  36/48 out back system  16 sams club golf cart battery’s 230 amp hour and 15 295watt solar panels .  I have a second fm80 solar charger and 15 more 295watt panels to mount next year 
     The panels are mounted on my roof  and starting DEC 1 I will be cleaning snow off the panels as my coffee cooks  every morning . 
     Ground mount your panels so you don’t need a 35’ pole to sweep snow . 
      I tried to plan a system that would be inexpensive and the guys on this site where very helpful,  but in the end I called AWS and the guys hook me up. 
      They  Gave me a Design in 2 hours , they took my visa over the phone and it showed up in a few days . 
      I’m in to it for 10 k or a little more . 
      You should buy your panels locally with racking so you can pic them up green mount ion electric
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭

    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭
    Few pic for you . 
     My battery’s are in the garage to the right on the other side of the wall .
      I’m sure a bunch of guys will be by to help you out with lots more Experience then I 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • PhotowhitPhotowhit Solar Expert Posts: 5,806 ✭✭✭✭✭
    It will be somewhat difficult to determine actual usage for some things... Like the Air conditioning, which will run off a thermostat and won't be a steady usage. Also look into what type of air conditioning you will use. Some are much more efficent than others. If it's an open design and mini split might be your best bet and a couple of big window units have come out in recent years that would handle an open floor plan big area, 1200 watt unit by Midea was the "first window AC to obtain the ENERGY STAR Most Efficient 2020 Certification" In the past they have made units for other manufactures that have been imported to the US. If it's too 'different' for you. LG also makes a dual inverter air conditioner in the 10,000-14,000 btu that are likely to work for you. They were the former leaders in Energy Star numbers;

    https://www.amazon.com/dp/B0867GMW9X/ref=twister_B086VZGZDM

    Some items won't overlap, you aren't likely too use a window fan and a air conditioner at the same time....

    I'd personally just use a standard fridge. Look for an efficient,  one and you should be around the same 1kWh a day (work backwards from the energy start numbers. 365 kWhs a year would be 1 per day...

    For now perhaps figure on a small inexpensive 24 volt system with 4 golf cart batteries for over night use. Measure your daily energy use with a house system measuring tool to figure out your common usage. 

    I wouldn't worry about flooded batteries too much if left fully charged. We had a moderator who would leave his batteries unattended over the winter in Canada. I think he completely disconnected them, but would have to go back and check.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    It's extremely difficult to justify a complete off grid  solar system for such a short annual useage, >15% of the year, maximum useage stated. To gain knowledge, power everything with a generator using a power recording device to record exactly what is needed, from this it will be possible to get relitivly accurate consumption figures for when it's time to retire.

    There is of course the noise of the generator to consider, it's possible to have the generator a distance away as higher voltage results in lower current, thus less losses but nothing beats the silence of solar power, these are known as tradeoffs. Work slowly, don't jump into anything prematurely, the cost of batteries along with their life expectancy  will offset the cost of fuel the generator will need for such short useage windows, I'm referring to lead acid batteries, other chemistries could be longer but have temperature restraints in sub freezing conditions that have to be taken into consideration.

    Don't take this as discouragement, most here who are full time off grid do so because there is no option relying on power generation 365 days of the year, subserdized by generator when needed, not the other way around, just have to be realistic.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭
    edited November 2020 #8
    Mike is very rite , you little Honda will power your place for years . 
     I ran a cheep champion 1800 watt genarator for 2 years 16 hours a day for just lights radio tv small power tools .
      I start it a 800 am turn it off at 1100 pm fri sat Sunday .
     I was only there on weekends  working on the place .
    I would use about 5 gallons every 3 days about 10 gallons a week so I’m sure you would get by with 100gallons of fuel easy ,plus oil changes , spark plugs per year . 
       I built a new house and had to have power for my CO in my area . 
     I use my place 10 days a month April to oct and every other weekend in the winter unless I’m planing on working on it . 
        My system just works with very little help from me . 
      We are around the same age and I hope to retire up there .  John
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • medic149medic149 Registered Users Posts: 4
    wellbuilt said:
    It looks like your numbers are very high to me .
     My cabin is 2800 sq feet and it will run on 2/300 watts with every thing running all day and 200 watts at night 
     I don’t even try to conserve power . 
     My place stays at 67o all summer  you probably won’t need much AC 
     you really need some solar or you will need to run the genarator a lot . 
     11/2 to 2 hours a day and maybe 6 hours once or twice a week . 
     A charge controller and 900 watts of solar panel is a game changer . 
      If you have any sun 😜. 
      At my place the sun gets turned off the day after thanks giving and it gets very dark till mid January . 
      Plus it snows every day till may .
     Im just south of   Oneonta down rout 28  . So about 2 hours away . 
       You can’t really start buying stuff because you need a complete system designed to power your loads 
      Your battery’s should be all the same age size and lot number . 
      Your inverter need to be sized to the loads the battery’s feed the loads the solar panels charge the battery’s . 
      It’s winter now and you will be buried in snow soon so I would not buy battery’s now . 
       You could just run off one of your little Honda’s for now . 
        I use a flex power one  36/48 out back system  16 sams club golf cart battery’s 230 amp hour and 15 295watt solar panels .  I have a second fm80 solar charger and 15 more 295watt panels to mount next year 
     The panels are mounted on my roof  and starting DEC 1 I will be cleaning snow off the panels as my coffee cooks  every morning . 
     Ground mount your panels so you don’t need a 35’ pole to sweep snow . 
      I tried to plan a system that would be inexpensive and the guys on this site where very helpful,  but in the end I called AWS and the guys hook me up. 
      They  Gave me a Design in 2 hours , they took my visa over the phone and it showed up in a few days . 
      I’m in to it for 10 k or a little more . 
      You should buy your panels locally with racking so you can pic them up green mount ion electric
    Thank you!!  This was a lot of great information for me to think about.  Especially since you're familiar with how little sun there is where we are  lol.
  • BB.BB. Super Moderators, Administrators Posts: 32,608 admin
    edited November 2020 #10
    A good start--Plan on 1,000 WH per day... Run LED lights, RV water pump, laptop computer, cell phone charger... Say you run the "stuff" for 5 hours in the evening (assume a 8 amps @ 12 volt or 4 amp @ 24 volt RV water pump--Not really much energy for 20 minutes of water per day)... Then the average available watt*hour or amp*hours per day would be (even 500 Watt*Hour per day system might even be fine if just lighting and cell phone charging plus some other random stuff):
    • 1,000 WH per day / 5 hours per day usage = 200 Watts average load (for 5 hours)
    • 1,000 WH per day * 1/12 VDC * 1/5 hours = 16.7 Amps average load (for 5 hours)
    Just taking a basic rule of thumb design... 2 days of storage, 50% max discharge:
    • 1,000 WH per day * 1/0.85 AC inverter eff * 2 days storage * 1/0.50 max planned discharge * 1/12 volt battery bus = 392 AH @ 12 volt battery bank
    That would be 2x 200 AH @ 6 volt Golf Cart batteries in series * 2 parallel strings for 4x GC batteries total (around $400 worth).

    To charge that--5% rate of charge for sunny weather use (possible genset backup charging). 10% suggested minimum for full time off grid--And 13% typical "cost effective maximum charging rate:
    • 392 AH * 14.5 VDC charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 369 Watt array minimum
    • 392 AH * 14.5 VDC charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 738 Watt array nominal
    • 392 AH * 14.5 VDC charging * 1/0.77 panel+controller deratings * 0.13 rate of charge = 960 Watt array "typical" cost effective maximum
    And then there is the array based on your daily loads and average sun. Fixed array facing south for Candem NY (zip 13316 seems to work better:
    (Wrong link--good/simple solar calculator) http://www.solarelectricityhandbook.com/solar-irradiance.html
    (Correct link for data below--more complicated but similar results): https://pvwatts.nrel.gov/

    This is based on a 1,000 Watt array (minimum for PV Watts), 43 degree tilt from horizontal, and 48% losses (52% off grid AC battery system overall efficiency):

    737 kWh/Year*

    RESULTS

    Print Results

    System output may range from 706 to 746 kWh per year near this location.
    Click HERE for more information.

    MonthSolar Radiation
    ( kWh / m2 / day )
    AC Energy
    ( kWh ave per month )
    Value
    ( $ )
    January2.84455
    February3.72546
    March4.66708
    April5.24728
    May5.41749
    June5.33708
    July5.82779
    August5.62769
    September5.31718
    October3.80546
    November2.86415
    December2.09334
    Annual4.39737$ 85

    Say you use the system from February through October--Or a minimum of 3.72 hours of sun average (Feb):
    • 1,000 WH per day * 1/0.52 off grid AC system eff * 1/3.72 hours of sun = 517 Watt array February "break even" size
    Just to give you a quick way to figure out what size MPPT solar charge controller (Amps @ XX volts)--Here is "minimum" Ampere rated MPPT solar charge controller suggested (assuming a 77% panel and controller derating):
    • 738 Watt array (10% rate of charge) * 0.77 array+controller derating * 1/14.5 volts charging = 39 Amp minimum rated MPPT solar charge controller
    So--That gives you enough power to run stuff in the evening (quiet time, some 12 VDC or 120 VAC lighting for late night usage)... And use the genset(s) when you need more power during the day.

    A 300 Watt 120 VAC TSW/PSW inverter @ 12 VDC input--This is a good one to take a look at. Includes "sleep mode" and remote on/off:

    https://www.solar-electric.com/morningstar-si-300-115v-ul-inverter.html

    Inverters "waste power" just being turned on (Tare Losses)... It is 6 Watts for this one, and in sleep mode less--And a remote on/off switch to save even more power...

    You have the choice of taking the batteries home during the winter--Or (for example) get 1% to 2% array to float charge the battery bank over winter (with a simple/small charge controller and the panel(s) mounted on a vertical surface to limit snow sticking to panel through winter).
    • 392 AH * 14.5 volts * 1/0.77 panel+controller losses * 0.01 rate of charge = 44 Watt minimum suggested float panel
    • 392 AH * 14.5 volts * 1/0.77 panel+controller losses * 0.02 rate of charge = 88 Watt max needed float panel
    Fully charged FLA batteries are pretty "happy" at freezing and well below temperatures--As long as they are kept charged. And sub freezing batteries have much slower self discharge--So a small "float array" is usually "good enough" to keep the batteries fully charged (even if panel is covered with snow for a month or two). Make sure all other loads are turned off (including a larger MPPT type charge controller--If you have enough sticky snow to cover the panels for weeks/months at a time otherwise--Even a few Watts of loads can slowly discharge the battery bank if no charging current is available).

    Nothing above is written in stone... But it does give you a good target for your initial paper design. And a very capable solar power system.

    There are lots of chargers, inverters, inverter-chargers, AC chargers, etc. available... You can look through our host's website, and other places, and see what prices/performance/options look good for you.

    Do not plan on taking a small system and adding too it... Most of the hardware will need changing (AC inverters are dedicated to one bus voltage--Larger solar arrays need larger charge controllers, and a simple GC Battery bank will last around 3-5 years of normal usage with good maintenance and charging regime. Some people move the "small system" to a guest building or shed--Or you may be able to reuse the solar panels (it can be difficult to even mix/match solar panels into a larger array).

    And there is always the chance that things will "walk" when you are not there... You probably don't want to leave a very expensive system onsite when you are not there.

    Your appliance energy usage chart is around 33,000 WH per day or 1,0000,000 WH per month (or 1,000 kWH per month on your utility bill)... While that is certainly "doable" for off grid power--That is a pretty big system. A standard North American home uses around 500 to 1,000 kWH.

    For a first power system that is of "reasonable" size... Try to live in the 3,300 WH (3.3 kWH) per day or ~100,000 WH (100 kWH) per month usage... That is about enough power to have a "near normal" electrical off grid life (albeit with lots of conservation, using alternative fuels like wood, propane, etc. for heating/cooking/hot water).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • medic149medic149 Registered Users Posts: 4
    Thank you so much, everyone!!  You've really helped me.  We hope to close on our off-grid cabin in a week or two.  Can't wait to start working on this project.  I may start off slowly with the solar and use generator most of the time.  Probably a small setup to charge the RV batteries and batteries for the DC fridge.   

    Thanks again!  I will be reading and learning a lot from this site.

    Andy
  • BB.BB. Super Moderators, Administrators Posts: 32,608 admin
    edited November 2020 #12
    Boy, my post #3 had lots of typos and such... Fixed typos and put in correct link for data posted below... Again, here is the PV Watts link:
    And highly suggested--Do some paper designs first--Before you purchase the first panel or battery... If you get stuff "on sale", it can be a real pain to mix in equipment that doesn't quite fit your system needs.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭
    I have bills small 300 watt inverter in a old trailer we stayed in it when we where building the cabin..
    I have 2 6volt battery’s, charge controller 500 watts of solar mounted on a deck roof in front of the trailer.
     I had plenty of power until the middle of November , the system is in its 6th year and still putting out power . 
     A couple solar panels would allow you to run your trailer 9 months out of the year with out even thinking about it .
    ‘I just ran the inverter 24/7 and used a ac radio / Samsung tv and real ac led lights c pac over night 
      I would get more compliments about the light bulb hanging on a wire over the picnic table on the porch. 
     A little power is a real plus
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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