Best time for opportunity loads?

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stmoloud
stmoloud Registered Users Posts: 111 ✭✭
edited August 2019 in Solar Beginners Corner #1
I estimate about 25A to bring my Samsung inverter fridge/freezer back to life after a rest of a day or two. This represents a little more than 10% of my usable 20 hr capacity. That's acceptable, especially when I'm confident that the day of resurrection and the following  day will be sunny. 
My question is if it is better to switch on the fridge during the bulk or wait until absorb charge is reached?  Forget about float as I hardly ever get there. This is also relevant to other opportunity loads of which I might want to take advantage.
Another related question is that as the aforementioned 25A is read off an inverter meter will that in fact be a true reading or should I add to the 25A some more since the source is AC?  I am on 240 VAC.
760W panel array, 4 x 6v 220 ah Crown batteries, Tristar TS-45 PWM controller,  no name 600 PSW inverter. 
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
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    Assuming the 25A is 25Ah, 
    A refrigerator would probably use less energy if it were on all the time as opposed to being used as an opportunity load, below is some logged data of my inverter refrigerator for February. This is real life use without attempting to conserve in any way, the average ambient temperature would be ~ 30°C. Using 25Ah would be approximately 600Wh on you system, if average ambient temperature were lower say ~20°C, Im sure my data would be somewhere close to 600Wh. The unit is a medium sized refrigerator freezer all settings on medium.

    If the 25A is the DC running current at 24VDC, that would be ~2.5A at 240VAC each hour of use would be 300Wh continuous running, it would probably take an hour to get down to temperature.

    Opportunity loads are best run when the battery is fully charged, utilizing energy that would otherwise go unused, doing it before will almost gaurentee the clouds to roll in :#

    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • stmoloud
    stmoloud Registered Users Posts: 111 ✭✭
    #3
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    Yes you are right on counts, my ambient is 16C to 12C depending on if the wind originates from the Antarctic.  Real solution is to add more PV, will do so when the funds come through. Thanks!
    760W panel array, 4 x 6v 220 ah Crown batteries, Tristar TS-45 PWM controller,  no name 600 PSW inverter. 
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