Hybrid Car – More Fun with Less Gas

How many panels ? ( to run 230 volt sprinkler pump 30 minutes a day?) - Page 24

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Posted by bealiba on July 22, 2008, 12:49 pm

No, you suggested the T105s and failed to provide the fill specs for
the sizing.

The 180 Ah is the minimum battery capacity required, not a battery
recommendation. At the required half hour discharge rate the minimum
battery capacity is still 180AH.

Ya gotta laugh. User information required, the user supplies the specs
for the panel. You pick a panel and put its specs into the formula. if
you prefer I at 17V at NOCT 2.94A. Use it.

What I did show is the correct formula for sizing a stand alone solar
PV system. That was my only intent. You have failed to supply true and
correct specs.This is not surprising in the least. You have no concept
of what is actually required for the correct sizing of a system.

The information supplied by the OP was just enough to calculate the
minimum battery capacity. Nothing more.

To seriously try to size a system to supply 2500 W for a half hour is
a waste of time. To attempt to build said system is a waste of money.

The formula is correct, you can't prove otherwise.

Posted by Ron Rosenfeld on July 22, 2008, 1:33 pm
On Tue, 22 Jul 2008 05:49:47 -0700 (PDT), bealiba@gmail.com wrote:

It is sad that, after all so many people have been trying to teach you, you
can still spout the same old drivel.

And you couldn't even do that correctly.

Certainly your widely disparate results have proven that that is the case,
for you.

Since it gives incorrect results, there's no need.  And since you can't
even understand your errors, there's no point.


Posted by bealiba on July 23, 2008, 11:43 pm
The correct minimum battery capacity is 180Ahs. IF you feel that this
is not correct you can try to prove it wrong.

Ah, a point, yes indeed. The point is that the formula is correct. The
minimum battery capacity is correct. You have yet to prove otherwise.

The problem here is that unless you have someone to hold your hand
throughout the process of system sizing you are simply unable to do
it. You need to be led by the hand through each step. Every little
piece if information spoon fed to you. Between you, Tweedledee, and
your bunk mate Tweedledum, who thinks that increasing the load will
reduce voltage drop, it is hard to tell which of you is the more

To those that have been watching this bit of street theater, the
formula is correct. BUT be aware, you need to supply an amount of
actual equipment specifications to use the formula. If you are
unwilling to provide this information then you would be better off to
hire someone to design your system.

Lets look at what Tweedledeed cant manage. i.e. User Input

Daily Load - 4250AH
System Voltage - 48V

A2      Daily load = 4250Wh - User Input
A4      Inverter Efficiency = 90% - User Input
A5      Account for inverter inefficiency - Load (A2/A4) = 4722Wh
A7      System Voltage = 48 - User Input
A8      Total A-hr demand per day (A5 / A7) = 122.55

B1      Number of days of autonomy = 5 - User Input
B2      Maximum allowable depth of discharge = 70% - User Input
B3      Battery capacity (A8 x B1 / B2) = 702.71Ah
B4      Lowest 24 hour average temperature =10c - User Input
B5      Temperature correction factor =.96 - User Input
B6      Adjusted battery capacity (B3 / B5) = 731.99
B7      Selected Battery - AS770 - User Input
B8      Selected battery discharge rate 120 - User Input
B9      A-hr capacity of selected battery = 840Ah - User Input
B10     Number of batteries in parallel (B6 / B9, rounded off) = 1
B11     Number of batteries in series (A7 / battery voltage) =24
B12     Check Capacity of selected battery at l20 Hr rate = 840 - User
B13     Capacity of battery bank at 120 hr rate (B12 x B10) = 840
B14     Daily depth of discharge (100 x A8 / B13) = 11.71%

C1      Design tilt -  45 degrees - User Input
C2      Design month  - June - User Input
C3      Total energy demand per day (A8) =98.38Ah
C4      Battery efficiency = 90% - User Input
C5      Array output required per day (C3 / C4) = 109.31
C6      Peak sun hours at design tilt for design month = 5 - User
C7      Selected module - BP 4175 - User Input
C8      Selected module I at 35.4 volts at NOCT 4.9A - User Input
C9      Selected module nominal operating voltage. = 24V - User Input
C10     Guaranteed current (C8 x 0.9) = 4.41A
C11     Number of modules in series (A7 / C9) = 2
C12     Output per module (C10 x C6) = 22.05Ah
C13     Number of parallel strings of modules (C5 / C12) = 5.51

I have marked all the points of user input. In all, there are 18
points where Tweedledee is out of his depth.

This formula does not take I have an average house as an argument.
The user must be prepared to supply the required information. If the
user is not prepared to do this work, then he or she should find a
designer in the phone book, say yes to everything the designer
suggests and hope that when something breaks the designer will show up
to fix it.

Posted by Ron Rosenfeld on July 24, 2008, 2:01 am
 On Wed, 23 Jul 2008 16:43:15 -0700 (PDT), bealiba@gmail.com wrote:

You wouldn't understand the proof.  Your ignoring previous postings as well
as your ongoing piffle is evidence enough of that.

Again George demonstrates his lack of knowledge of battery chemistry, and
cannot even quote what he wrote correctly!

What George wrote in his specifications:

And George expects a battery bank with these specifications to power a 2500
watt pump for 30 minutes daily in the real world.

He will not provide complete specifications for his magic battery.  Nor can
he find a manufactured battery that even comes close to his specification.

When a battery was suggested that seems pretty close to *HIS*
specifications, he ridiculed it as being inadequate.

    Maximum allowable depth of discharge = 70%
    Round Trip efficiency   = 85%
    Capacity at 100 hr rate = 240Ah  

I guess maybe he thinks the 85% efficiency round-trip efficiency vs. his
90% efficiency will somehow make this battery a LOT worse than his

Maybe he thinks that the T105 has a HIGHER capacity than what he quoted is
also a cause for alarm.

But the fact remains that he continues to claim that HIS battery
specifications are adequate, and that those of the T105 are inadequate.
George would only use T105's in a golf cart.  But he cannot tell us what
battery he would use in this system that would work and also match his

For panels, George's input is equally baffling:

He can provide neither the test standard that requires 14 volts, nor a
commercially produced panel that meets these specifications which HE input.
The values also do not match those that the OP provided.

But he somehow expects this panel with these specifications to work in the
proposed system.

Nick Pine had it correct years ago when he wrote about you:  "Who would
hire this nitwit?"

Posted by bealiba on July 24, 2008, 5:14 am
Which is to say Tweedledee can't prove that the minimum battery
capacity of 180Ahs is wrong. Nothing new there.

Almost all deep cycle batteries will stand up to a 80% Maximum Depth
of Discharge. You really do need to learn the difference between
"Maximum DOD" and "Daily DOD". A world of difference between the two.

The 180Ah is the minimum capacity required to do the job.

And the Battery Efficiency, Surprise, surprise it works.

George never specified a battery. You specified T105s.

George never specified a battery. You specified T105s.

Crap battery. Barely up to the job of running a golf cart. Certainly
worthless for a rate of C0.5

Not likely.

George never specified a battery. You specified T105s.

George never specified a panels.

George never specified a panels.

George never specified a panels.

Nick Pine, mmm, The man with the solar garage. Still laughing over
that one.

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