Help me pick parts for a off grid cabin.

I live in Alberta, Canada, and I'm planning off the grid cabin. I need help picking a system that will be powerful all year round. I would be a water pump, refrigerator, tv, computer and some low wattage lighting. In the winter I would need enough power for (2) 500w vehicle block heaters for 4hours, before the sun rises. I could be their for weeks at a time throughout the year.

Would this be enough?

(10) Trojan L16HC 2100AH @ 20hr or Trojan T-105 equivalent?
(6) 180w-200w Solar Panels Need help with brand and size?
(1) Outback FM80
(1) 2000W-3000W Power inverter hopefully pure sine wave, but doesn't have to be?

What else do I need? I would downgrade if anything is overkill.


  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: Help me pick parts for a off grid cabin.

    Well for solar panels , check out and the Sun branded Evergreen seconds modules

    As for your amount of panels off the top of my head your off by more than 2x ( need more panels ) , I'm sure the more verbose posters will take the time to show you why
  • BB.
    BB. Super Moderators, Administrators Posts: 33,502 admin
    Re: Help me pick parts for a off grid cabin.

    Well, using this site which calculates Grid Tie solar installation power generation by month/year.

    1,200 watts of solar panels for Edmonton Alberta (?) would give you deep in January and average of 91 kWhrs per month or about 3 kWhrs per day with a fixed array and default settings.

    Since you will be using batteries and inverter(s), assuming 80% efficient battery and 85% efficient inverter (losses over and above those of a Grid Tie only system):

    3 kWhrs per day * 0.8 * 0.85 = 2 kWhrs per day (average over January).

    December is even worse... 52kWhr/month:

    52/30 * 0.8 * 0.85 = 1.2 kWhrs per day (average over December).

    Your request for 4 hours * 500 watts * 2 cars = 4 kWhrs per day (not including TV/Lights/etc.)...

    It is going to be a series of trade-offs... How much solar power you want in the winter vs possible "more power than you need in the summer" vs the fuel costs for generator/heaters in the winter.

    Solar trackers, reflections from snow, tilting more vertical for better sun collection in the winter, etc. can all help... But Solar Power for electrical heating is normally not the best use of solar $$$. Are there other options that might work for you???

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: Help me pick parts for a off grid cabin.

    So If I run the block heaters off a generator, the rest of the setup will be okay?
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Help me pick parts for a off grid cabin.


    This exercise will likely entail several steps. We need to start by defining your projected average daily energy requirement (Watt-hours per day, or Wh/day).

    For example, the two 500 W block heater operating for four hours each will require the following amount of net energy: 2 heaters x 500 W/heater x 4 hours/day = 4,000 Wh/day.

    We need to continue this exercise for your other loads:

    (a) One energy-efficient fridge in the winter = 1,000 Wh/day
    (b) One TV @ 150 W x 6 hours per day = 900 Wh/day
    (c) Five CFL lights @14 W x 5 hours per day = 350 Wh/day
    (d) One computer (laptop?) @85 W x 10 hours/day = 850 W/day
    (e) One water pump @100 W x 1 hour/day = 100 Wh/day

    So far, we’re at 7,200 Wh/day, or 7.2 kWh/day. Anything else? Microwave? Fan(s)? modem for satellite? Printer? DVD player? Kitchen appliances?

    More later,
    Jim / crewzer
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Help me pick parts for a off grid cabin.

    Look to reduce your loads overall first.

    I would look at the possibility of using a Propane fridge first. There are several threads on this forum regarding the pros and cons of propane vs pv powered fridge. Consider a different water pumping system, perhaps a low voltage submersible like the shurfo. You could also consider a gas powered pump that pumps high volume for a short time, or a high volume ac pump run off your generator while you are in a charge cycle. It would be cheaper to install a bigger pressure tank(s) and run the pump less often than have a 24/7 demand pump. I pump into my P-tanks when the sun is good and the batteries are full and that gives me enough water for several days. (Use water efficiently)

    I agree with Jim about using a generator for the block heaters. A Honda eu 1000 or 2000 would run the block heaters much cheaper than Pv. Also consider adding insulating blankets in the engine compartment to reduce heat loss.

    Remember to avoid the ready, fire, aim syndrome. Look every seriously at your loads, and try to come up with ways to reduce them without reducing your desired standard of living. It is amazing how small your loads can become if you are fastidious about using them carefully. It is much cheaper to conserve and plan carefully, than it is to build a system for every perceived need. Also, a well designed system can always be added on to as the needs arise.

    We live quite comfortably on ~300 watt/hours/day. This includes lighting, water pumping, lap top charging, satellite modem, phone , stereo etc. We have no TV, and have an outhouse so our water use is quite small. We run some small tools off the system, sewing machine, drills, grinders etc. but I use the generator for any large draw shop tools, saws etc.

    Good luck,


    PS Crewzer and Bill et al, are terrific fountains of technical knowlege. Others of us (myself included) are full of opinions, some are even good ones. Read all you can through the threads here and you will learn more every day.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Help me pick parts for a off grid cabin.

    Look into propane fired block heaters, or a hot water loop to heat the blocks.

    Vehicles are in a garage right ? what about an engine blanket to keep them warm?

    last bet is Solar hot water w/propane backup for blocks

    PV electric is wayyy toooo expensive

    Block heaters can be run off mod sine inverters, they don't need pure sine inverters

    Consider a small diesel co-gen (hot water & electric) for the cloudy days.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    gen: ,

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Help me pick parts for a off grid cabin.

    I don't know why I didn't think of this before,,,, (Thanks again Mike!) Webasto makes a gas (or diesel) fired coolant heater for most vehicles. Set the timer, the heater fires up using fuel from the vehicle, and a small pump, heating the coolant throughout the system much more efficiently than any block heater, and presto, you've got a warm vehicle. Not too cheap to buy, but great and very fuel efficient. Available through Clow/Darling in Canada. Also available used on e-bay.