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Please check calculations in Excel for system sizing please? - Small System Sizing Calculator.xls (0/1) - Small System Sizing Calculator.xls (0/1)

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Posted by Anti-Spam on August 23, 2007, 6:15 pm
Nearly new to this topic, just need a couple of points of view on my
calculations for a small system design. Thanking you in anticipation.

Posted by Anti-Spam on August 23, 2007, 6:39 pm
Sorry could not post the file, try this instead please. Took me a
while, but I got there in the end.


Posted by bealiba on August 26, 2007, 12:15 am
By way of further explanation,

The first thing you need is the energy audit which you have.

So if this load is to run from an inverter you need to calculate the
inverters loss at this point;

Load 720Whs X .9 = 800Whs / 12V = 66.67 Ahs

This is the actual load of your system including the inverter

Now you can calculate the battery requirement. You need to know the
days of autonomy (1) and the maximum allowable depth of discharge (%
recommended by manufacturer, say 70%) 66.67Ahs X 1day autonomy /
70%MaxDOD = 95.24 Ahs capacity.

This is then adjusted for 24 hour average daily temperature (say
10C);  95.24 / .96 = 99.21Ahs.

Now you can calculate the panel requirement. 66.67Ahs / battery
efficiency .9 = 74.07Ahs of panel output.

If you would like to have the complete spreadsheet drop me an email
and I can send it to you.  The formula is progressive and should be
calculated in the correct order for best results.

Posted by wmbjkREMOVE on August 26, 2007, 3:00 pm
 On Sun, 26 Aug 2007 00:15:34 -0000, bealiba@gmail.com wrote:

Previously you wrote that he needed 102Ah. You should make up your
mind which wrong number to use. You might also finally learn about
Peukert's equation and the effect it would have on discharging a
battery at ~ C/5 rate. http://www.amplepower.com/pwrnews/beer/  A
reasonable exponent of 1.1 would make your numbers another 30%

Why are the charger specs from B30 and B31 of his spreadsheet still
MIA from your calculations? Does it have anything to do with
"unexpected babies"?

Why would he start correspondence with a quack when spreadsheets are
readily downloadable from reputable sources?

http://www.citlink.net/~wmbjk/tbfduwisdumb.htm  (just updated with
Ghio's spreadsheet)


Posted by bealiba on August 26, 2007, 10:19 pm
 On Aug 27, 1:00 am, wmbjkREM...@citlink.net wrote:

http://www.lowexpecations.com/http://www.citlink.net/~wmbjk/tbfduwisdumb.htm (just
updated with

Gee wayne, I forgot that you can reduce your load by using a charger.
How is that done wayne? Do you plug your charger into the inverter to
charge the batteries as you run your loads?

Is this the secret of the magical load reduction that gives you your
two days autonomy?

No numbers, no design, no hope.

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