Northern Canadian Solar

Sun DogSun Dog Solar Expert Posts: 115 ✭✭
I need some help trying to determine the appropriate size of solar array for an off-grid home in northern Canada. I don't know how to size it because the difference between our good months and bad months is so extreme. According to the inforomation from NASA we average 6.17 kWh/m2 for June, but only 0.49 kWh/m2 in December :cry:

Our winter use will be 10,000 watt hours/day with ~3000 watts being the max load at any given time

thanks,
Steve

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Northern Canadian Solar

    Let's ask the loaded question: why do you want solar?
    Frankly, trying to supply solar electric at your latitude in Winter is daunting. Even in the Cariboo it's unreasonably difficult. Six hour days don't produce a lot of usable solar. Maybe two hours on a good day. Now try recharging a significantly sized battery bank when you have less than half the typical number of "equivalent good sun" hours.

    That 10 kW hours per day figure is working against you too. As always, the first step is reducing consumption as much as possible. Frankly, trying to supply that many AC Watt hours per day in Winter up North adds up to a ten kilowatt array. :cry:
  • Sun DogSun Dog Solar Expert Posts: 115 ✭✭
    Re: Northern Canadian Solar

    Well because I think (or want to think) that it can be cost effiective in the long run. I don't believe wind is a viable option here so I am trying to find the right blance of solar and diesel. We could likely trim that 10 kWh figure some but I work from home and need to have my computer going 10 to 12 hours a day from Mon-Fri. That, plus our composting toilet amount to 3000 watt hours each day. Clearly we are going to have to run the generator a lot from November to February but I hope that we could incorporate solar to help a great deal for the rest of the year. Positioned at the optimal angle we have the following numbers according to NASA in kWh/m2

    Jan 1.01
    Feb 2.30
    Mar 4.16
    Apr 5.45
    May 5.79
    Jun 6.17
    Jul 6.11
    Aug 4.85
    Sep 3.40
    Oct 2.28
    Nov 1.32
    Dec 0.49

    That is my dilema, a ~10 kilowatt array is what I would need if I based it on December but during June and July it would be total overkill. How does one calculate the happy medium? (assuming it does exist)
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Northern Canadian Solar

    You might want to look at this thread on composting toilets: http://forum.solar-electric.com/showthread.php?t=5999&highlight=composting+toilet
    Maybe there's some power saving to be had there.
    Desktop computer? Switch to a laptop. We ran the desktop unit and dropped more than 100 Watts by changing. If you run a desktop 10-12 hours that could be 2 kW hours right there. Another big power user in office equipment is a laser printer.

    Just for reference, we run an electric refrigerator (16 cu. ft.), computer/satellite modem/phone set-up, lights, radio, water pump (1/3 HP), digester pump (1 HP), and microwave off the minimal system in my sig. It needs to be bigger, because much of the usability comes from load shifting. Still, in the neighborhood of less than 3 kW hours per day.

    If you can run PV Watts http://www.nrel.gov/rredc/pvwatts/ you can get some idea for the power you might expect. It doesn't run on my Linux netbook, or else I'd do it for you.

    In terms of lessening diesel usage, I'd suggest shooting for 100% of your Summer or Spring/Fall power supplied from solar, and let the Winter needs be supplemented by generator. Off the top of my head, you'd be looking at more like a 4 kW array for your 10 kW hours daily.

    Your days must be in the 16-18 hour range in Summer. If the panels were on a tracker you could yield significant amounts of power from whatever size array. It's a shame it's not practical to store Summer "harvest" for six months. With AGM's, maybe. But I wouldn't want to count on it.
  • Sun DogSun Dog Solar Expert Posts: 115 ✭✭
    Re: Northern Canadian Solar

    Marc, thanks for the links. I would agree 100% that without power to the heating element that the composting units can not deal with the liquid. We are too close to a lake and on exposed bedrock so just having it overflow is not an option. I have tried running a lower powered fan but at continual temps of -40C and below the exhuast vent freezes over. Other than building something myself, the Natureshead unit looks to be the best option for us.

    Much of my computer consumption is in the three 20" LCD monitors that I use for work. I'm experimenting with only using two, will see how it goes. Not sure how much those LED lit LCD monitors might save, should help a little. Don't use the printer that much so that isn't an issue.

    I have tried PVWatts but also like the format of this one https://glfc.cfsnet.nfis.org/mapserver/pv/index.php?lang=e I think June 21 is pretty close to 19 hours from sunrise to sunset but of course it never really gets dark at that time of year. There is a 6 week period that it never gets dark enough to see the stars. Those trackers look to increase the summer potential by +50% but of course summer isn't my problem and as they seem rather pricey. I think my money would be better spent elsewhere. Of course if I came up with some kind of cost of effective geothermal system then I could pump all that energy into the ground during the summer and then retreive it come winter, but that is a pretty big "if".

    Forgot to add that 10000 watt hours is our winter usage. Summer usage will drop as no cars to plug in etc.
  • BB.BB. Super Moderators Posts: 26,666 admin
    Re: Northern Canadian Solar

    Other ways of heating? Small propane/diesel heater or heat exchanger for the composter? (problems with methane and flames?).

    Properly insulated (i.e., heat goes into evap. liquids instead of going through walls to heat basement/outdoors?

    Work with others to create a sanitary liquids dump away from shoreline?

    Computers and monitors do use the electricity... Hard to get good numbers on configurations that will work for you other than going into the computer store with a kill-a-watt meter and test systems as would have them configured.

    Putting computer/monitors to sleep when not there--Not very useful if you sit in front of them 8-12 hours per day.

    -Bill

    PS: You can setup a more fuel efficient Winter configuration in one of two ways:

    1) Size your genset to run at ~50%+ load your "base loads" during the day (computers, composter, battery bank, etc.) for 12 hours per day... Then "at night", turn everything off you can and run from AC inverter + Battery bank... You might be able to take some waste heat (hot water, hot air) to use for composter keeping workspace warm (using waste genset heat in winter may actually not be practical for many reasons--I really don't know the answer).

    2) Size your battery banks to run 10 kWH per day (2 days no sun, 50% maximum discharge = 4x your daily loads). Size genset to efficiently recharge the battery bank:
    • Battery AH capacity * ~0.13 Rate of Charge = AC to DC charger capacity.
    • Size larger Genset ~2x AC to DC battery charger input power requirements. Run genset every 1-2 days and "quickly" and efficiently "bulk charge" the battery bank back to 80-90%+ state of charge in winter.
    Your goal (in winter) would be to use the genset at 50% or more of rated power to supply power (either lower daily loads, or larger recharging every couple days). Running a genset at way below 50% loads guzzles fuel and can be very hard on diesel.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Northern Canadian Solar

    Aside from the usual admonitions about doing everything to conserve power, (your 10KWh/day is huge. Try to get it down to ~ 3-5 and you would be well served.

    As for the composting toilet, I have some experience in a similar sub-arctic environment. (personally we gave up on the composting toilet for exactly the reasons that you are having trouble and reverted to a well dug outhouse, far from the lake shore, even though we are on the shield, we found a vein of gravel ~ 6' deep!)

    What I did was build a propane heater for the compost heater to replace the electric heater. A small burner, burning ~ 1000 BTUs or so should be enough to keep the compost warm. If memory serves I used a regulated LP line, but coupled to a high pressure camp stove for the burner, so that it burned just barely. I used a thermo couple in the flame so that it was safe. I then used the fan system from the toilet to bring the heat into the compost chamber.

    It worked quite well, and composted very well, but I found that it fundamentally wasn't worth the effort. If memory serves, (and it was ~10 years ago) it burned 20# of propane per month.

    It is certainly an idea that might be worth reviving if your composting toilet is in the house. As you have discovered, the composter will just plain not work without external heat.

    Tony

    PS I still have the guts of the thing in the summer shop. Perhaps I will dig my way into it today through the snow and look at it in detail again.
  • Ralph DayRalph Day Solar Expert Posts: 871 ✭✭✭
    Re: Northern Canadian Solar

    Tony,
    Was it an earlier incarnation of that compost heater that removed your eyebrows (temporarily)?

    I could never get my Sunmar to properly compost, even with the heater on...it just dried things out to cannon ball consistency. Maybe more liquid would have helped, but I gave up after the fungus gnats that wouldn't die!

    Ralph
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Northern Canadian Solar

    Ralph,

    Your memory is sort of correct. Actually, I quite literally nearly cut off my nose as a result of a brain fart. The very sharp edged vent pipe blew off during ignition with my face in the way, catching and taking my nose with it!. (Can't hardly see the scar any more!)

    As for composting toilets "working" properly. I found, after working with a number of them over the years, the quantity of the water was critical. Too dry, and it didn't compost, to wet and it wouldn't compost. The compost pile needed to be the consistency of a well wrung sponge. The addition of popped popcorn to add carbon and airspace made a huge difference.

    Bottom line however, it was way too much work, (some every day!) to be worth the while, when a good outhouse works just fine.

    Tony
  • mike95490mike95490 Solar Expert Posts: 7,225 ✭✭✭✭
    Re: Northern Canadian Solar
    icarus wrote: »
    .....
    It is certainly an idea that might be worth reviving if your composting toilet is in the house. As you have discovered, the composter will just plain not work without external heat. ....

    Compost toilets can't evaporate the gallons of fluid without heat. In cold, the process slows down, but drowning the microbes does not help.

    It's a tough situation.
    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

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • SchmidtSchmidt Registered Users Posts: 12
    Re: Northern Canadian Solar
    I need some help trying to determine the appropriate size of solar array for an off-grid home in northern Canada. I don't know how to size it because the difference between our good months and bad months is so extreme. According to the inforomation from NASA we average 6.17 kWh/m2 for June, but only 0.49 kWh/m2 in December :cry:

    Our winter use will be 10,000 watt hours/day with ~3000 watts being the max load at any given time

    thanks,
    Steve

    Hello Steve,

    Yes, the drastic swing in available sun-hours in our northern country does require a reliance on a generator. I have had the opportunity to design and supply several systems to Northern Canada and in your location, around 60% of your yearly power consumption can be provide by PV, with the rest of course provided via generator.

    A off grid solar system can be a cost effective solution if this is a new build and you're looking at the high cost of installing the utility's infrastructure.

    I can provide you with a complete system cost and performance analysis as well as system design and supply. I PM'd my contact info, so feel free to contact me if you wish.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Northern Canadian Solar
    mike90045 wrote: »
    Compost toilets can't evaporate the gallons of fluid without heat. In cold, the process slows down, but drowning the microbes does not help.

    It's a tough situation.

    The problem is that the water content is critical. Too much, and you kill the microbes, too little, and you kill the microbes. I found that I had to test the material every day. The heat tends to dry it out too much depending on use patterns, so adding water may become necessary from time to time.

    Tony
  • Sun DogSun Dog Solar Expert Posts: 115 ✭✭
    Re: Northern Canadian Solar

    Thanks for all the comments and suggestions guys. We have been running our Sunmar for ~15 years (it is in the house) and with the heating element running have been pretty happy with it. I would be very interested in hearing more about your heater Tony, when you have a chance. I suppose we are too soft, but an outhouse at -45C is a hard sell. Factor in that I will have to go twice as often (with my 4 year old) and I don't see it happening.

    I'm fairly confident we can get our 10KWh winter usage down to 9 but after that it is going to get tough. I am going to head out to the local Staples and see if they will indulge me to test a fulling running laptop with a 17" screen that is simultaneously driving another 20" LED lit LCD monitor. Our fridge is another <1KWh/day but a propane fridge just doesn't seem like the answer to me. $4000 upfront cost (for a 15cu/ft) and $300 to $400 a year in propane. That sounds like money better invested in solar panels to me and in the winter it is no problem for us to be freezing containers of water outside to be put back into the fridge. That said, am I missing something in the propane vs electric fridge comparison?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Northern Canadian Solar

    Let's check the perspective here:

    You're already running off-grid on full diesel power? No grid?
    In that case any solar is going to be an improvement. In fact, just adding batteries/inverter would probably save fuel because the gen isn't loaded to 50% capacity all the time. So a few hours of gen time to recharge batteries that will supply the power the rest of the time saves fuel. Add solar, even if Winter harvest is terrible, and you save even more fuel.

    I don't think a propane refrigerator is a good idea either. Not for full-time use with a family.
  • Sun DogSun Dog Solar Expert Posts: 115 ✭✭
    Re: Northern Canadian Solar

    Currently on-grid but will be cut off at the end of this summer. Too complicated to explain but suffice it to say if we could stay on I would.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Northern Canadian Solar

    If it has anything to do with money,,, it aint gonna be cheaper to go off grid!

    Tony
  • Ralph DayRalph Day Solar Expert Posts: 871 ✭✭✭
    Re: Northern Canadian Solar

    Just to back Tony's statement...I charged with utility power last week. 10kwhrs x 14cents/kwhr (roughly) $1.50. The equivilant charge done with my 10kw diesel genset...6hrs x 2.5litres/hr x $1.00/litre = $15.00 All figures are rough, but you get the picture.

    Ralph
  • Sun DogSun Dog Solar Expert Posts: 115 ✭✭
    Re: Northern Canadian Solar

    It's not about money. I would pay a lot to stay on, but it is out of my control.
  • stephendvstephendv Solar Expert Posts: 1,571
    Re: Northern Canadian Solar
    I suppose we are too soft, but an outhouse at -45C is a hard sell. Factor in that I will have to go twice as often (with my 4 year old) and I don't see it happening.

    I'm planning on using the Separette composting toilet in our new cabin: http://www.separett.com/, it has 2 clear advantages over the in-toilet composters:
    1. The composting is done outside away from the home, and it doesn't have to be controlled or heated. You just leave it there for more than 1 year until all potential pathogens are dead.
    2. It separates urine and solids right at the source you don't have to spend money/energy drying the stuff out after the fact. Also means you now have a good source of fertilizer :)

    The downside is that it requires emptying every month or so which may not be everyone's cup of tea.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Northern Canadian Solar

    It's minus 36 this morning,, and I am soon out to the out house. I understand how that is a non starter for most people!

    Tony
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Northern Canadian Solar

    Actually, not a bad experience this morning,, except for the 35 km wind!

    T
  • SchmidtSchmidt Registered Users Posts: 12
    Re: Northern Canadian Solar

    Hello Steve,

    As many others of said, it is important to be as efficient as possible. Loads, especailly "phantom Loads" that are typically ignored and run 24/7 can add up very quickly. Your goal of 9-10kW / day during the winter months is typical for a full time off grid home.

    Cheers.
  • Sun DogSun Dog Solar Expert Posts: 115 ✭✭
    Re: Northern Canadian Solar

    Tony, you need to move north! It is only -2C up here :cool:
  • Ralph DayRalph Day Solar Expert Posts: 871 ✭✭✭
    Re: Northern Canadian Solar

    Or south...-2C sitting in Lake Ontario,

    Ralph
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Northern Canadian Solar

    Warming up, only supposed to be -26 tonight, although we are usually ~ 5-8 degrees cooler.

    Won't see freezing until sometime late next week, so they say.

    T.
  • Sun DogSun Dog Solar Expert Posts: 115 ✭✭
    Re: Northern Canadian Solar

    I thought I was doing a good job of getting our power consumption down but it turns out I was picking up pennies and leaving dollars on the ground. Using some of the suggestions posted here have helped a great deal. I finally got over to Staples and checked on the consumption of a laptop with a 17.3" screen. It ran between 22-42 watts. I wasn't able to determine how much more it would use while driving another monitor but I doubt it will be that much. For now I am going to use 70 watts for it with a 20watt LED backlit LCD monitor. If I can get my usage down to 10 hours/day that knocks 2300 watt hours off of my daily load compared to using my current computer/monitor setup.

    I also found a 16.5cuft fridge that is rated at 300kWh/year. Unfortunately a wood stove isn't practical for us and I had given up on pellet stoves because of their high power consumption. I just found out about some from Thelin that are rated at only 27 watts. I'm looking into confirming that number, but if true it will be half of the power that I was expecting to use in a Toyotomi oil space heater.

    All that, some LED lights and a few other things and I believe I have gone from 10kWh/day down to 6. I have been spending some time on PVWatts and the NASA site. While their numbers are close, there are some fairly large differences in the kWh/m2 for the winter months. In general, is one site considered more accurate than the other?

    Steve
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