I HAVE A 2,400 WATTS INVERTER, 8 BATTERIES AT 12 VOLTS EACH.I
CURRENTLY USE A GENERATOR TO RECHARGE THE BATTERIES. I LIVE IN THE
COUNTRYSIDE IN HAITI WHERE WE HAVE AT LEAST 9 HOURS OF SUN. GASOLINE
IS EXPENSIVE AND RARE. WHAT TYPE OF INVERTER SHOULD I USE TO KEEP A
REFRIGERATOR (600 WATTS), 2 FANS AND SOME BULBS RUNNING AT LEAST 6
HOURS A DAY.
ANTICIPATED THANKS, 
ANDRE MANIGAT

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Request for Question Clarification by redhoss-ga on 19 Nov 2003 07:27 PST

Are you looking for a solar panel that would fully charge 8 deep cycle
12v batteries in a day having 9 hours of full sun. Also, would you
require a device to keep the panel positioned for full exposure to the
sun or would you do this by hand.

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Clarification of Question by doudou58-ga on 20 Nov 2003 13:41 PST

The question  was  what type of solar panel should I use.

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Clarification of Question by doudou58-ga on 21 Nov 2003 14:24 PST

Thanks for your help. Let me try to be clearer. In Haiti which is a
tropical country, we have at least 9 hours of sun per day. I already
have a 2,400 watts inverter and 8 deep cycle batteries to use your
technical jargon(ask me what it means , I would be very embarassed to
answer)at 12 volts each. I use a generator ro recharge the batteries
because i have a 600 watts refrigerator that seem to drain all the
power from the batteries. I know, or I assume that fans(2) do not
really use too much power though I let them run all night . The
question now is: What type of solar panel should I use to keep all of
the above appliances mentioned running  especially the refrigerator
the minimum 4 hours a day. Or Let's eliminate the refrigerator from
the picture to make things easier. Do I really all these batteries,
provided that many folks in my neighborhood use 40, 50 watts solar
panel 2 batteries and it seems to work okay.
I hope to hear from you soon,
thanks again,
andre manigat

Hello Andre,
I think that I now fully understand your problem. First we will
calculate your total power requirement.
This is easily done by totaling your amperage used with all your
appliances connected using this formula.

Watts=volts x amps 
OR
Amps=watts/volts

Refridgerator: 600 watts/120 volts= 5 amps
Fans (2): 4 amps (I used an average box fan)
Lights (3): 1 amp (I assumed 100 watt bulbs)

So, when you are using all at the same time (4+5+1) 10 amps are required.

An average 12v battery (in good condition) has a capacity of about 100 amp hours.
Therefore, you could draw 10 amps for 10 hours from a "fully charged" battery.
This explains how your neighbors get by with only 2 batteries.

What we really need to look at is how long it takes to charge a
battery with a given
supply of current (amps). A commonly used formula is:

Charge time = 1.2 x Amp hours (of the battery being charged) / charge
current (amps)

A standard 80 watt solar panel provides 4.58 amps at 17.5 volts. To
fully charge one 12v battery:

Charge time = 1.2 x 100 / 4.58 = 26.2 hours

If you are only running your appliances for 6 hours per day, then you
would not be fully
discharging your battery. You might estimate that the actual charging
time would be about
0.6 (6/10) x 26.2 = 15 hours. If you had two 80 watt solar panels, you
could cut the charging time
in half or 7.5 hours which would allow you to recharge your battery in
your 9 hour day.

If your neighbors are only using 40 watt panels, I will bet that they
are using fewer appliances than you.

I would say that you will need two 80 watt solar panels (or 4 40
watt). You have plenty of 12v batteries which is good for
additional storage capacity and your generator gives you back up for
extended cloudy periods. All of these
calculations are based on full sunlight on your solar panels.

I have tried to make all this as simple as possible. I would not
normally spend this much time answering a
$5.00 question, but I admire people who are self sustaining and even
though we have cheap electric power
where I live (Idaho, USA) it may not always be that way. Please do not
hesitate to ask for more information
if this does not solve your problem.

Good luck, Redhoss