What do i need to get started in this setup

swampcreek
swampcreek Registered Users Posts: 4 ✭
in Solar Beginners Corner #1
I just bought a shipping container 40’x8’x8’ and walled in 24’ of it.  I insulated the walls and ceiling with r30.  I installed a100 amp panel box to run a few things.  One light, two AC exhaust fans(fart fans 105 watts i think, not shipped yet) a small tv for weather updates and maybe dvd, and maybe a small heater/ac unit on wheels that i can plug into a wall.   Basically a storm shelter and maybe a guest house/drunkards overnight.  I want to run the two fans on a timer switch to come on and vent it a few hours a day.  

i can rig the panel up for a generator if i need to.  But i was hoping i can spend the same amount in solar.  I have access to a couple electrical  fork lift  batteries.  6volt i think.   I dont know anything about it really.  Im on the Florida Georgia line so it gets hot.  I just want it to vent every day mostly.  So any guidance would be greatly appreciated.  
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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    #2
    Get a 24v dc fan from a car and a 60 cell panel, sun hits it, it turns on sun goes down its off.
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    It is hard to justify a "real" off grid solar power system for random use... Solar is pretty expensive power (plus new batteries every ~5 years, etc.). Off Grid Solar works OK if you are using the power most every day (say 9+ months a year)--However, if it a random weekend thing, all the rest of the days, no power used/no energy harvested from the sun (a typical off grid power system only stores around 2+ days of "useful" energy... The rest is lost (and makes a poor return on investment).

    You really need to define the power you need (12 VDC or 120 VAC--For TV/DVR).

    As Just Starting says, a single mid size 60 cell (Vmp~30 volts) and an old car radiator fan will move air during the day. If you want power overnight, a 500 WH to 1,000 WH per day (run LED lighting, cell phone charger, small fan, laptop/tablet computer)...

    Just to give you an idea of what a 1,000 WH per day would look like (and the basic math). Using rules of thumb for a reliable daily use off grid system:
    • 1,000 WH per day * 1/0.85 AC inverter eff (if using inverter) * 2 days storage * 1/0.50 max discharge (longer battery life) * 1/12 volt bank = 392 AH @ 12 volt battery bank
    That is 2x 6 volt @ 200 AH golf cart batteries in series * 2 parallel strings for a 12 volt @ ~400 AH battery bank (4x golf cart batteries). You could get away with a 12 volt @ 200 AH (2x golf cart batteries) if did not need as much power.

    The solar panels would need to meet two requirements... Battery charging current, and to support your loads with hours of sun per day for your location...

    For charging current 5% rate of charge works for a weekend / sunny weather system. 10%+ works better for a full time off grid usage system:
    • 400 AH * 14.5 volt charging (four GC batteries) * 1/0.77 solar panel+controller derating * 0.05 rate of charge = 377 Watt array minimum
    • 400 AH * 14.5 volt (four GC batteries) * 1/0.77 solar panel+controller derating * 0.10 rate of charge = 753 Watt array nominal
    • 400 AH * 14.5 volt (four GC batteries) * 1/0.77 solar panel+controller derating * 0.13 rate of charge = 979 Watt array typical cost effective maximum
    And there is sizing the array for your daily loads and sun... Fixed array, near Tallahassee Florida:
    http://www.solarelectricityhandbook.com/solar-irradiance.html

    Tallahassee
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 63° angle from vertical:
    (For best year-round performance)

    JanFebMarAprMayJun
    4.66
         		5.39
         		5.80
         		6.11
         		5.98
         		5.38
     
    JulAugSepOctNovDec
    5.08
         		5.06
         		4.96
         		5.27
         		4.85
         		4.51
     

    Sunny area in winter, afternoon thunder storms in summer? Use 4.51 hours of sun for "December break even" (perhaps use a genset some, or nobody comes by in winter?
    • 1,000 WH per day * 1/0.52 off grid AC system eff * 1/4.51 hours of sun per day (December) = 426 Watt "break even December"
    Use a 300 Watt AC inverter (if you want AC power). Would work very nicely and reliably... More solar, less genset runtime, happier battery bank...

    A starting point for discussion....

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
    With a small or moderate size system, you will not get much winter time electrical heating. look for in-floor hydronic heating with a propane fired boiler tank.
    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 ,

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  • swampcreek
    swampcreek Registered Users Posts: 4 ✭
    #5
    Ok.  I think i will go with some dc fans on the panels and hook the panel up for a generator.  I think i can get a knock off honda generator from harbor freight to hook to my panel box as needed.   
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    As always, watch for prevailing winds and genset exhaust (or if the genset and building are in a "hollow"). You don't want Carbon Monoxide collecting in the building (a simple battery powered CO alarm would be highly recommended).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • swampcreek
    swampcreek Registered Users Posts: 4 ✭
    #7

    What good are these?  I have 4 laying around. 
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #8
    They are ~7 Watt fans... So two small "12 volt panels" in series, or even 1x 12 volt panel should work. 4x 7 watt fans, then probably ~30-60 Watt panel(s) total will work fine.

    http://www.farnell.com/datasheets/2343843.pdf

    You need a large enough panel (wattage) and volts to get the fans spinning. Higher voltage, they will spin faster. Depending on the specific fan model, the "high volume" fans at full speed can be pretty noisy. These fans seem to be on the low power/low RPM/low volume side--So should be quiet.

    The other option, a combination of low/high venting (low vents let cool air in, high vents let hot air out). Solar powered fans do not really move that much air--And some folks with solar powered roof fans found that just adding the new holes/venting in the roof was enough to move air through the structure (and they found, after a couple of years, the fans had failed, but the attics still did not get hot).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • swampcreek
    swampcreek Registered Users Posts: 4 ✭
    #9
    I have access to four of these batteries for $25 each.  Can i get 200 watt panels and a small inverter to run my fans?  I am ordering rafiator fans from amazon.  12v 6.6 amp. 80w

    I was thinking about making two 12 volt systems.  Would that be better than 24v ??

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    edited April 2020 #10
    You really need to define the type and amount of loads you want to run... Watts * Hours per Day = Watt*Hours per day... 
    Microwave, or a 10 Watt LED lamp, RV water pump, or 1.5 HP deep well pump, 10 minutes a day, or 24 hours per day (like a refrigerator).
    More or less, a "small system" is around 500-1,000 WH per day. Very capable systems for Non-Refrigerator/Non-Well pump loads.
    A mid size system is around 3,300 WH per day... A full time off grid, very conservation minded home/cabin. But not cheap--$10,000 to $20,000 (depending on your ability to find bargains, low cost vs name brand components, etc.).
    Anything that "moves stuff" (air, water, etc.) or "heats things" (water, cooking, house), uses a lot more energy.
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Wheelman55
    Wheelman55 Registered Users Posts: 244 ✭✭✭
    #11
    Invest in a metal roof above the level of the container letting air pass between roof and container. Give yourself a 10’ awning all around as well. The sun is just brutal. 
    Off-Grid in Terlingua, TX
    5,000 watt array - 14 CS 370 watt modules. HZLA horizontal tracker. Schneider: XW6048NA+, Mini PDP, MPPT 80-600, SCP. 390ah LiFeP04 battery bank - 3 Discover AES 42-48-6650 48 volt 130ah LiFePO4 batteries
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