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Solar dump load after batteries charged

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  • #16
    Originally posted by tahir afd View Post
    How many solar panels of 150w and inverter require to run an ac refrigrater of approx 170watt
    How many hours of sun will you have? Assuming the fridge runs 30% of the time @ 170 watt (ouch, this is not going to be good)
    Starting surge of the fridge motor is going to need a 1Kw pure sine wave inverter, and it "should" work most of the time.

    8hrs x 170w = 1360 watt hours consumed by fridge
    Assume 4 usable solar hours summertime, and 2 hours winter time ?
    rule of thumb is array has to harvest 2x the daily use (this accounts for system losses of about 50% total)
    Winter - you need a 1400 watts of array (will vary if you have more or less solar hours) (10 panels)
    Summer - you need a 700 watts of array, but will have dead batteries in winter with less sun (6 panels - can't use a odd number like 5)

    Battery requirement is 1360 x 4 = 5440 watt hours of storage, gives you 1 cloudy day before battery dies.
    24V battery would be 226ah, or 4ea, 6V Golf cart batteries would do the job (wired in series)
    Powerfab top of pole PV mount (2) | 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



    • #17
      Hi, I use a 24volt DC 900w element in my hot water cylinder. When the SOC reaches 100% the aux relay on my Midnite Classic turns on a 24 volt relay. This relay is also controlled by the cylinder thermostat. The relay switches a 80amp solid state relay which puts battery current onto the element. When SOC reaches 98% it turns off. I have on/off time delays programmed in too. Often with more than 26amps going to the batteries, the element just stays on alot of the day.It works very well. I just need to fit a timer to turn off the relay an hour or two before sunset to go into the night with 100% SOC. the panels are 2kW. The cylinder 44 gal and it takes about 9hrs to heat the water from cold.