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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) - Page 2

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Posted by bealiba on August 23, 2007, 9:55 pm

Your sizing is out.

Your total use taking into account inverter inefficiency will be

Battery Ah requirement will be 102Ah

Daily Depth of Discharge will be 88.89%, resulting in short battery
life (@ your battery capacity of 75Ah)

360 Watts of panel input required for 4 PSH

Posted by wmbjkREMOVE on August 23, 2007, 11:17 pm
On Thu, 23 Aug 2007 21:55:30 -0000, bealiba@gmail.com wrote:

No, it's your reading comprehension that's out.

No. His spreadsheet indicates that he's planning to supplement with a
charger. So start by deducting the 264Wh charger output from the total
energy needed to calculate the solar portion required, ~450Wh.

No. The loads total 180W, and the charger supplies 132W. So if the
loads are run concurrent with the charger and/or simultaneously, then
none of that energy need make a trip through the batteries. If not,
adjust calculations accordingly. Also depends how much, (if any) of
the loads will be concurrent with the solar production. Say, 600Wh,
probably less, which makes the DOD perhaps <65% with his planned

No. His planned 200W should be about right. His numbers are well in
the ballpark, yours are stuck in traffic.... again. See here for
previous examples.  http://www.citlink.net/~wmbjk/tbfduwisdumb.htm


Posted by bealiba on August 24, 2007, 7:23 am
 On Aug 24, 9:17 am, wmbjkREM...@citlink.net wrote:


Posted by bealiba on August 24, 2007, 7:46 am
 On Aug 24, 9:17 am, wmbjkREM...@citlink.net wrote:

Oh my god, it really is just too funny to pass up. His spreadsheet
says that:

"Total Wattage per day 720W." I assume that he means Whs. With the
inverters inefficiency taken into account this is 833 Whs. Remember,
an inverter is a load as it uses energy from the batteries to run,
hence the need to take into account its efficiency. This is the load
that must be made up for by charging. Using a charger or panels or
wind or even a bicycle driven charger will not reduce the load one

Given the level of "expertise" shown in your first point there really
is no point in continuing.

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