solar powered generator

EarlEarl Registered Users Posts: 1
hello iam a newbe and looking for a solar power generator to run my refrigerator, fans, tv ,and to charge my cell phone any advised is much appreciated i thank you advance.


  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Hi Earl, and welcome!

    In general, off grid solar will be more expensive that the grid, so long as saving money isn't your goal if you have the grid near by, let's talk!

    Lots of old threads to read through with good advice.

    An off grid solar system involves several parts, a solar array of panels that change the sun's rays to electrical energy, a battery to store the energy, a charge controller to regulate the battery charging, and usually an inverter to make the DC energy in the battery into AC energy for home use.

    Without knowing exactly how much energy you will be using, and where you live and your willingness to use alternate means to charge the batteries during periods of cloudy days. It's hard to give a good idea of needs and costs. So anything would be a crapshoot. 

    A new modern fridge will use about 1 - 1.5 Kwh's of energy each day and will likely use more energy than anything else you have specified. Calculations on a system just to run the fridge, might look like this; 1.5 Kwhs of electric needed each day, 2 days autonomy (days with no solar charging before you run a generator) charging when the battery reaches 50% to lengthen the battery life. 1.5 Kwhs x 2 = 3 Kwhs x 2 (50% charging) = 6 Kwh battery bank.  Something like 4 Trojan T105golf cart batteries at 230 amp hours at 6 volts = 1380 watts or 1.38 kwhs will get you close.

    A single string of 4 batteries to lessen voltage drop, and you have a 24 volt system. To charge a 230 amp battery bank you will want an array that will provide 10-13% of the battery bank capacity if used on a daily basis (you can use 5-6% of this would be a weekend cabin without loads during the week) So 23-30 amps delivered to the battery bank in bulk charging at 24 volt nominal system voltage. This would seem to indicate 28 volts (charging voltage for a 24 volts system) at 30 amps or 28x30=840 watt array. but solar panels are rated in ideal conditions, they usually only produce 75% of their rated value so it works out to be around 1120 watts needed. 

    If you went with 72 cell panels you could use a cheaper PWM charge controller, They produce about 35 volts VMP which is high enough to effectively charge a 24 volt bank with some minimal losses. If you go with 60 cell panels you would need a MPPT type charge controller to use them effectively to charge a 24 volt battery bank, you would also receive about 10% more charging current if used with 72 cell panels but the cost difference is substantial between the 2 different types of charge controllers.

    Lastly an inverter, Something large enough to kick off a fridge which has a compressor. While the fridge will only use 100- 160 watts running (generally) it might take 5-10 times that wattage to start. Usually the minimal inverter I would recommend to run a fridge would be around a 1000 watts.

    Throw in some fuses/breakers, a combiner box perhaps for the panels...

    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.
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