Minimum Wattage Portable Solar Generator / Power Station To Run 2021 LG 27 Cu FT Frig

PaulInTexasPaulInTexas Registered Users, Users Awaiting Email Confirmation Posts: 1
Hello. Newbie here. Doing my research to purchase some portable solar, perhaps Ecoflow. Looking forward to it. What is minimum comfortable wattage system to purchase for portable solar generator. My frig is a 27cuft LG, rating 3.5A, defrosting wattage 350w. I tried calling LG customer service and was given very high number for surge wattage, 2,500W, which seems high for new frig. Any guidance?


  • 706jim706jim Solar Expert Posts: 495 ✭✭✭✭
    Well a lot depends on how often this fridge is going to be operating. If 24/7 then my estimate would be at least 1000 watts of solar and a 1500 watt inverter preferably true sine wave. A fridge is a relentless draw once running and many have a fairly high starting surge.

    But you can forget about running that beast on a couple of 100 watt panels.
    Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 29th year.
  • PhotowhitPhotowhit Solar Expert Posts: 5,976 ✭✭✭✭✭
    Yes that's a pretty high surge. My 20 year old 13 cuft fridge will work on an 1100 watt Exeltech, though it's a gifted inverter and will clip wave a bit to maintain some functionality with higher demands.

    In general, you've done well in giving us some numbers, but the one we really need would be the average daily load of the fridge. This is easiest to look at it's energy start numbers and figure out the average daily load. Additional info we would need is the fridge going to be in the suggested average temps when you are running it. I think they use 74-75 degrees for energy star testing. Will it be used, open and shut, more often. I think they use 6-8 times opened if kids will be around this will be a silly small number.

    Here is 1 LG 27 cuft fridge energy star label;
    LG Side by Side Refrigerator LRSXS2706V  RC Willey
    Looks to be about middle of the road, for similar models. Low end for the features it has. 

    726 kWhs / 365 days each year would be a load of about 2 kWhs per day.

    You could also plug the fridge into a Kill-A-Watt type meter and measure the energy use for a couple days or weeks.

    International Kill A Watt P4400 P4400 - 4895  WF Computer

    Once you establish the load, you will want to know where you are setting this up.

    Systems will be very different if you are where daily sun is the norm vs where there is very little sun during times of the year. Some places have less than 2 hours of direct sun light on average during the short days of winter, some average over 4 hours perday.

    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, 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.
  • BB.BB. Super Moderators, Administrators Posts: 32,925 admin
    Typically, the inverter needed to power a "standard" fridge is around 1,200 to 1,500 Watts. And most inverters will surge around 2x their nameplate wattage...

    The "integrated" all-in-one inverter/charger/battery bank units--They tend to blur the numbers and make it difficult to compare with standard component based systems.

    How many years will a solar generator last?

    Depending on the brand and the quality of the battery, you can expect a solar generator to last years. For example, the EcoFlow DELTA Pro uses a state-of-the-art LFP battery, which will last for 6500 cycles before reaching 50% of its original capacity. A battery management system helps prolong the device's lifespan for a lasting, cost-effective solution.

    For example, the Ecoflow units seem to be rated for 6,500 cycles to 50% battery bank capacity (many "off grid" systems/battery bank are rated to 80% or maybe 70% of remaining battery capacity. Rating to 50% is a significantly impaired capacity ~17.8 years of daily use. And few (if any) talk about how to replace the battery bank after they cells have cycled out (issue of how to access/repair the bank, and could you even get new replacement cells 5-10 let alone 20 years down the road???). (Photo of internal battery bank+BMS for one Ecoflow model).

    If you assume linear battery degradation, say ~9 year battery life to 75% capacity. That is actually better than most of the other units out there (from what little I have seen).

    For RV, dry camping, and emergency backup power use where you may use 30 days a year--That is 10+ years of usage.

    Compared to the popular Jackery which (I think) is a 500 Cycle to 80% battery bank life:

    And with the "all in ones", they seem to have much less surge rating than standard inverters... For example a 1,500 Watt Jackery will surge to 1,800 Watts (my eyes start glazing over trying to find straight forward specifications).

    And battery capacity (Echoflow does allow you to connect external battery bank modules to many of their products) it usually around 1 hour of operation at 100% rated capacity... I.e., a 1,500 Watt Jackery will run about 1 hour or 1,500 Watt*Hours of useful battery capacity.

    The Ecoflow seems to flow that marketing guide:

    I.e., a 3,600 Watt unit will have 3,600 Watts of (internal) battery capacity.... And I would guess that most units are output limited to roughly 1x bank capacity... I.e., if you have a 2,000 watt unit, the (internal) battery bank will be rated to ~2,000 WH too.

    For battery cycle life--The Ecoflow is really nice. Even if you assume 3,250 to 75% remaining battery life--That is much better than almost all the others out there.

    However--Without knowing your loads and amount of solar (if you are going with off grid solar), we really need to go back to the basics. What is your daily power needs (peak watts, and Watt*Hours per day of energy needed). For example, using Photowhit's Energy Star tag number of 726 kWH per year... Working the math:
    • 726 kWH per year / 365 days a year = 1.989 kWH per day = 1,989 WH per day (usually the yellow tags are fairly conservative)
    If you were to pick a 1,500 Watt all-in-one unit, that would be around 1,500 WH of battery capacity:
    • 1,500 Watt*hour / 1,989 WH per day fridge = 0.75 days = 18 hours of running
    While I would suspect that a 1,500 Watt unit will probably run your refrigerator, it would (on a warm day with average number of door openings per day) would only run the fridge for 18 hours per charge. Typically, suggest a minimum of 2 days of battery capacity (say using 70% of battery capacity) for a full time off grid situation:
    • 1,989 WH per day fridge * 2 days of stored energy * 1/0.85 AC inverter eff * 1/0.70 battery capacity derating over time = 6,686 WH suggested (minimum full time off grid) battery rating
    And then there is the solar array... Lets guess you are around Houston, fixed array, and you adjust the array tilt once a month for best seasonal harvest. Note that solar panels only work in full sun... Pretty much any shadows (tree, overhead power lines, etc.) will cut harvest by 50% to 100%. The pretty pictures of Jackery and Ecoflow systems in deep forest cover and/or not even facing sun--The solar panels are pretty much useless. Some numbers:

    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel where the angle is adjusted each month to get optimum sunlight.

    Lets say that you will use a backup genset when needed for the 3 months of winter... And use November 4.10 hours of (long term) average sun per day. The solar array needed for this would be around:
    • 1,989 WH per day fridge * 1/0.61 off grid AC Lithium system eff * 1/4.10 hours of sun per day (Nov) = 599 Watt solar array for November "break even"
    If you want to minimize the genset use--Usually only suggest that you plan on using 50% to 65% of planned solar harvest for "base loads" that need to run 24x7 (like refrigerators, home lighting, etc.). Don't run optional loads (washer/dryer, TV, computer, vacuum cleaner) on the days when the sun is not shining.

    Don't get me wrong, the Ecoflow seem to be a relatively nice unit with >9 year of battery bank cycle life (one of my local Costco stores has an Ecoflow sales counter there now). There are few (if any) all in one systems that match that spec.

    HOWEVER, you are matching a portable solar power system with a fixed home load (a refrigerator). The high expense and compactness of a portable system with a (typically) fixed home power need (emergency backup)?

    I am kicking myself a bit--I just purchased a Jackery a month before and--possibly--I would have got a smaller Ecoflow instead (longer battery cycle life)... But in reality, I would be using the all-in-one for portable/small emergecy power--Not to power my fridge.

    I keep an old Honda eu2000i (2,000 Watt surge, 1,600 Watt run) around to run a couple fridges/freezer for my home. More or less--One genset + 2 gallons of stored fuel per day--And I am all set for backup power (and extra fuel for the car if needed to bug out). 10 gallons of gasoline (with fuel stabilizer, transfer "old fuel" to car once a year) and I am set to go for the next wild fire/earthquake. Worked great for my inlaw's home (used an external fuel tank adapter that works with smaller Honda eu gensets) when they had power shutdown a couple years ago for wildfire concerns.

    As Jim and Photowhit say--It is all about your personal energy needs. A simple Kill-a-Watt type meter is a great way to start.

    Measure your loads for a few days to get an average... And for emergency power, you may want to power some other loads... Such as lights, laptop computer, cell phone, radio... placing some solar panels out for a few days of emergency use is OK. For a "fixed installation", a fixed array (bolted to roof, free standing racking, etc.) is going to be more permanent and not get blown around the back yard (or stolen) if left outside for weeks/years on end.

    Solar "Generators"--I think they are over sold/marketed for powering home refrigerators. Leave a fridge/freezer closed during a power outage--And you can coast through a 24 hour power outage. The last Texas wide power outage (snow/ice/clouds/no wind)--Home heating was a big issue (frozen/broken water pipes). The ideal plan addresses your "black swan" event. For me it is earthquakes and utilty shutdowns due to wild fires (poor/differed utility maintenance, hand in hand with California public utility commission--The utility was setting some of these wildfires in windy/dry weather).

    A genset is many times a better solution (gasoline storage--Always an issue. You can get smaller gensets that run off of propane these days--Easier to store and great if you have propane).

    There are larger genset that run from natural gas/propane/gasoline too--You can even get one from Costco at the moment. Note that large 10 kWatt gensets will suck the fuel like no tomorrow vs a small 2 kWatt inverter-generator (something like 12 hours on 8 gallons of fuel on 10 kWatt unit vs 9 hours on 1 gallon of fuel with small inverter-genset)... Again, the kill-a-watt type meter is your friend. And figuring out your loads/enegy needs is the place to start. "tri-fuel" "gasoline"

    Granted if you need 3,500 Watts to run your home (50% of 7,500 Watt genset)--Then that makes sense for your needs. Also, very nice if you have natural gas or propane on property already... Much easier, usually cheaper (and safer) than storing gasoline.

    If you only need 1/4 of 1,600 Watts (400 Watt) to run your fridge (fridge is typically 120 Watts and 350-600 Watts defrosting once a day)--Then the small genset may be a better choice.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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