Wind Power Logic ?

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Wind Power Logic ?

Postby daveO on Tue Mar 09, 2010 4:20 pm

Thought I would ask for some guidance here.

After the latest (expected) shock from Eskom, I have started to think about alternate energy for some basic things around the house.

Now not being an expert electrical person, can anyone tell me if I have the right logic here .... ?

Am looking at wind powered generators but not too sure about the maths.

A wind turbine ( yes, I am on a very 'breezy' hill ) generates ( it's specs say ) 1 kW. ( I assume this is per hour, and at optimum speed ? )

So that 1000w at 12 volts = 83 amps.

So I connect this to a deep cell battery ( 105 Ah ) and it will take 1.27 hours to charge.

The system requires a charge controller, so when the battery is fully charged and registers 14 volts, it switches the input from the turbine to a heating element, say, feeding my pool ( I know : minute amount of heating, but protecting the battery ).

On the other side of the battery, I have a 1000W inverter. So this takes the 105 Ah 12 volt from the battery and converts to 220 volt ( 105Ah x 12v ) to 1260 Watts, and assuming there must be some loss in the process, say 15%, I get out 1071 Watts. ( and 1071 W / 220 V = 4.86 Amps )

Now I have 10 energy saving bulbs ( 11 w each ) = 110 watts total per hour, and the battery and inverter should run these for 1071 / 110 = 9.7 hours.

I have used ( Eskom-less power ) of just over 1Kw. I have saved a grand total of just R 1 ?? Well, today at least. for the month R30, for the year R365, and for as long as my system doesn't require any costly maintenance.

Is my logic here correct ?
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Re: Wind Power Logic ?

Postby windgat on Wed Mar 10, 2010 11:50 pm

Hi Dave. Some problems in there. Firstly, 83 amps is a lot - you would need very thick wire, or would lose a lot of power to heating of the wire.

Secondly, you are confusing watts and watt hours, when you convert amp hours to watts. Any measure over time is watt hours or amp hours. Watts and amps by themselves are instantaneous measures. Using water as an analogy, watt hours (or amp hours) is like volume, and amps or watts is like a flow rate.
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