Complete Newbie-Looking For Help

mf12345mf12345 Registered Users Posts: 1
edited July 13 in Solar Beginners Corner #1
I am a complete newbie to solar. Been dealing with power outages lately and tired of storing gas and lugging out generator. 
Is there a solar kit I can buy that would have everything needed to run a fridge or chest freezer during power outage? Thanks. 


  • BB.BB. Super Moderators, Administrators Posts: 32,019 admin
    edited July 13 #2
    Welcome to the forum MF12345,

    You will find lots of people that will sell you kits... And some of them may actually work fine at a decent cost.

    However you need to better quantify your loads/energy needs and at least do some paper system designs to figure out your basic hardware needs. Then looking for solutions (and there are companies that will build custom "kit" solutions too).

    First statement--Off grid solar is "not cheap". And using off grid solar as a "backup system" is even "more not cheap". Running a refrigerator or freezer from solar--That pushes from a small to a mid size solar system (which is not cheap either).

    I will "do the math" here for a system design based on lots of guess work here... My SWAGs are you are around Allentown PA, and you are losing power from Ice Storms? So you may lose power a few days to a week at a time? And, at the very least, run your standard home fridge OR freezer from solar with a few LED lights and cell phone charging (no water pump, heater/central heat/etc.).

    An very good energy star rated refrigerator/freezer may run around 500 kWH per year +/- (energy star hang tag):
    • 500,000 WH per year / 365 days per year = 1,370 WH per day fridge
    So lets call your load a refrigerator (~120 Watts running, 500+ Watts defrosting) and a few LED lights/cell phone chargers or 1,500 WH per day.

    First sizing the AC inverter... That would be ~1,500 to 1,800 Watts suggested. Keep to 12 volt system (simple/cheap). An 1,800 Watt 24 vdc inverter would want around a minimum of 360 AH @ 12 volt battery bank. Or 4x 6 volt @ 200 AH Flooded Cell Lead Acid Deep Cycle batteries in series (24 volts) * 2 parallel strings (for 400 AH). To charge that battery bank:
    • 400 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 940 Watt array minimum (emergency backup)
    • 400 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 1,879 Watt array nominal (possible full time off grid)
    • 400 AH * 29.0 volts charging * 1/0.77 panel+controller deratings * 0.13 rate of charge = 2,443 Watt array "Typical" cost effective maximum
    And looking a fixed array facing south in Allenton PA:

    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 49° angle:
    (For best year-round performance)

    Choosing December average per day hours of sun:
    • 1,500 WH per day * 1/0.52 off grid system eff * 1/2.81 hours of sun per day (Dec) = 1,027 Watt array "Dec" Break even
    If you don't want to run a genset hardly ever--Then you will want to assume that the system will produce and overage worst case harvest of 65% to 50% of predicted harvest:
    • 1,027 Watt array * 1/0.65 base load fudge factor = 1,580 Watt array @ 65%
    • 1,027 Watt array * 1/0.50 base load fudge factor = 2,054 Watt array @ 50%
    So a 940 to 2,054 Watt array is certainly justifiable (some genset runtime to keep batteries up during winter outage) to almost never running the genest.

    Typical golf cart batteries will last ~3-5 years under use/standby to ~7 years in standby and kept cool (room temperature or lower--FLA batteries like to be 75F or less).

    Or there is looking at a standby genset that runs from propane or natural gas (which do you have)?

    I have Grid Tied solar for my home--In the last 65 years, I have had a week or two outage (I was not even in school yet) to a few days last year do to "stupid" California forestry practices, poor/almost nill utility maintenance, and over abundance of caution with utility shutdowns.

    I cannot (at least to date) justify a battery based system... Just a smallish Honda EU2x00i genset and 2-3 gallons of gasoline per day per home was enough to keep several fridge/freezers running, lights, and even a fish pond happy (my home and in-laws' home). And the inverter-generators were so quiet, could hardly even hear them in the house.

    A good place to start--Get a Kill-a-Watt type energy meter and see how much power you need per day...

    Gensets need almost no maintenance when not running (I "pickle" my gensets after use--Hardly ever need--Drain fuel, teaspoon of oil spark plug hole, etc.). Batteries "age" from the moment they are manufactured and are just as consumable as fuel and oil for genset.

    Your thoughts?

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SurfpathSurfpath Solar Expert Posts: 439 ✭✭✭
    The Maestro Bill gives lots of good advice. 

    I hear you about the power outages, but there is no cheap easy “solar” solution. If you are sizing for a regular non inverter fridge you might as well be planning a modest solar system for a small house. All Batteries age, and need babying. I second what Bill talked about in regards to a small portable generator. I have the same one as he does and it’s no trouble.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
  • SurfpathSurfpath Solar Expert Posts: 439 ✭✭✭
    If you do choose to go solar….
    What kind of fridge/freezer are you looking at? I have a 3300watt inverter that burns 25 watts on idle without any loads. However I now have a full sized inverter fridge that runs all day between40 and 280 watts. I could probably run it plus my house 24/7 with just a Morningstar Suresine 300 inverter (peak 600watts, idle 450 milliamps). So you don’t need to have a massive system, it’s just that I am not aware of any small Pre wired kits that are able to run a decent amount of panels, enough to charge a battery bank big enough to run a regular fridge.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
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