Can I use the same battery that I am charging?

[thaddeus333]

I am trying to set up my dad with a system to run his fridge, tv and a few random lights. I have a 140 watt 12v panel. Apparently I need roughly 150 Amp hours per day to run his needs(fridge is 6.5 amp at max load, tv and other items acount for roughly another 25-40Amps. My question is: If I purchase a 225 Amp hour battery and I only need 100 of those amps daily, can I use the battery while it is being charged by the solar panel? If so what size Amp hour battery would be the most efficient and cost effective? I am new at this and any help is greatly appreciated.

[Sunking]

Well to answer your title question, yes you can use a battery that is being charged as that is what a properly designed system does.

However what you are doing is not a properly designed system. Assuming you intend to use 150 AH out of a 12 volt battery (1800 watt hours) neither your solar panel, charge controller. or battery is large enough. If you tried on the second day your battery would be completely discharged and pretty much destroyed.

You would need at least a minimum 750 amp hour battery at 12 volts, and depending on location would need a 1500 to 700 watt solar panel with two 60 amp charge controllers. About $6000 worth of equipment.

Back to the ole drawing board.

[russ]

Hi Thaddeus - Welcome to Solar Panel Talk!

Russ

[jockellis]

Amps, AC DC

Sunking, if he inverts from his panel, and here I have to assume his Dad's fridge, tv and assorted lights are AC, he will be upping the voltage by a factor of about 10 which would drop his amperage by the same factor, would it not, or down to about 22 amps without factoring in the heat loss at the inverter?

[Sunking]

Sunking, if he inverts from his panel, and here I have to assume his Dad's fridge, tv and assorted lights are AC, he will be upping the voltage by a factor of about 10 which would drop his amperage by the same factor, would it not, or down to about 22 amps without factoring in the heat loss at the inverter?

Forget amps, think energy. a 12 volt 225 AH battery has 12 volts x 225 AH = 2700 watt hours. He wants to use 1800 + conversion losses which add up to 2700 wh per day.

With a 140 watt panel at best in winter all he can generate is 500 watt hours per day and he needs 2700 wh per day. Does Bankrupt ring a bell.

[thaddeus333]

Thanks for your informative replies

Thank you for the info. I think my dad will have to re think his options at that price. From what I can deduce from you replies. I need to be able to produce at least 2700 whours per day in order to run the appliances. Which in winter time lighting would require at least 800 watt panels to be on the safe side. Correct?? So if I wanted to set him up with an emergency solar 180 watt solar panel that runs into a charge controller and then down into a battery bank and then out to an invertor in turn to my needed appliances. The panel I am planning to build contains 60-6x6 cells. Their specs are:

Efficiency Eff (%) 16.7-17.9

Power Ppm (W) 3.99-4.27

Max. Power Current Ipm (A) 7.89 - 8.16

Short Circuit Current Isc (A) 8.49 - 8.73

Max Power Voltage Vpm (V) 0.510 - 0.521

Open Circuit Voltage Voc (V) 0.623 - 0.625

I am told they are 3w cells with an 8 amp rating. Does the charger have to be exactly 8 amps, can it be higher? What size of deep cycle battery would be best suited for this arrangement? Is there a way to figure out how long that battery will run a 1500 watt invertor at full usage? What is the best I can hope for on a sunny day on the california coast? I understand that this is a lot of questions, but I am a quick learner and appreciate all of your inputs. Thank you again.