Hybrid Car – More Fun with Less Gas

How many panels ? ( to run 230 volt sprinkler pump 30 minutes a day?) - Page 3

register ::  Login Password  :: Lost Password?
Posted by wmbjkREMOVE on July 6, 2008, 3:01 pm
On Sat, 5 Jul 2008 23:11:27 -0700 (PDT), bealiba@gmail.com wrote:

Who is "we"? Do you imagine that your cargo cult has more than a
single member?


Posted by Ron Rosenfeld on July 6, 2008, 10:14 pm
On Sat, 5 Jul 2008 23:11:27 -0700 (PDT), bealiba@gmail.com wrote:


YOU are the only one who has been lying.  And all you have been spewing is

YOU have falsely claimed that I recommended some battery size to the OP.

YOU have done this by taking my recommendation for a *panel array size*,
and running it through your useless (in your hands) spreadsheet, using
inputs that you have made up.  And YOUR spreadsheet provides for the same
20% factor in panel array sizing, which YOU obviously are unable to

YOU cannot even copy the OP's panel specifications to your spreadsheet

YOU have recommended multiple systems that won't meet the requirement of
daily running of the OP's system.

YOUr last recommendation will NOT run the OP's system 24/7 at his location.
Simple simulations show a 23% shortfall using a larger battery!  Of course,
you have never provided full specifications for your 180Ah battery which
was the last one you recommended, so a more precise shortfall of your last
proposed system cannot be predicted.

YOUR lowest recommendation for panels (amongst your many recommendations)
is 10% MORE than my recommendation, yet you persist in claiming that mine
is oversized!

YOU really are a piece of work.  


Posted by bealiba on July 6, 2008, 11:23 pm
As I have already predicted, lots of claims from Tweedledee and
Tweedledum and no maths to back up their claims.

Posted by Ron Rosenfeld on July 7, 2008, 2:44 am
 On Sun, 6 Jul 2008 16:23:39 -0700 (PDT), bealiba@gmail.com wrote:

The math to calculate the panel array size was provided in my first post,
but it seems that you've not been able to understand it.  All you can do is
rant about a 20% overestimate for a battery about which I wrote nothing.

And you keep claiming that my 10 panel array is oversized by 20%; whereas
your 11 panel array (or maybe your 17 panel or 154 panel recommendations)
is OK.

You can't even enter the OP's data correctly into your spreadsheet.

But if you want more real data, all you need to do is provide the specs on
your 180Ah battery, and the simulation is simple to do.

Give me the specs on your 180 Ah battery, and I'll give you the numbers for
a simulation of your 11 panel, 180 Ah battery system for Kilauea, HI.

George's Battery:

Nominal Capacity:    180Ah
Nominal Voltage:    ???
Round Trip Efficiency    ??
Min state of charge:    ??
Float life:        ?? yrs
Max charge rate:    ? A/Ah
Max charge current:    ? A
Lifetime throughput:    ? kWh

Also a Capacity curve (A vs Ah) and a Lifetime curve (DOD vs Cycles to

Because of the location, there's probably no need for you to supply a Temp
vs capacity curve or coefficient.  The temperatures don't vary that much
from the annual mean of 24C.

Posted by bealiba on July 7, 2008, 6:37 am
My, my, Tweedledee is busy today.

Trojan 225Ah T105s

It is not ten panels , it is 11. You added 20% on top of the daily
load right after you adjusted the load for inverter losses.

2.94A adjusted to 2.65A for losses.

The 180 Ah capacity is the minimum required for the system as
calculated from OPs data.  At B9 actual battery can be specified. you
are the only person so far to suggest a particular battery i.e. Trojan
T105s. As you feel that this battery is suitable for the application I
included it in the formula. The following is the result

A2      Daily load = 1250Wh
A4      Inverter Efficiency = 85%
A5      Account for inverter inefficiency - Load (A2/A4) = 1470.5
A7      System Voltage = 12
A8      Total A-hr demand per day (A5 / A7) = 122.55

B1      Number of days of autonomy = 1
B2      Maximum allowable depth of discharge = 70%
B3      Battery capacity (A8 x B1 / B2) = 175Ah
B4      Lowest 24 hour average temperature =15c
B5      Temperature correction factor =.97
B6      Adjusted battery capacity (B3 / B5) = 180.5
B7      Selected Battery
B8      Selected battery discharge rate 100
B9      A-hr capacity of selected battery = 225Ah
B10     Number of batteries in parallel (B6 / B9, rounded off) = 1
B11     Number of batteries in series (A7 / battery voltage) =1
B12     Check Capacity of selected battery at l00 Hr rate = 225
B13     Capacity of battery bank at 100 hr rate (B12 x B10) = 225
B14     Daily depth of discharge (100 x A8 / B13) = 54.47%

C1      Design tilt
C2      Design month
C3      Total energy demand per day (A8) =122.55Ah
C4      Battery efficiency = 90%
C5      Array output required per day (C3 / C4) = 136.2
C6      Peak sun hours at design tilt for design month = 5
C7      Selected module
C8      Selected module I at 14 volts at NOCT 2.94A
C9      Selected module nominal operating voltage. = 12V
C10     Guaranteed current (C8 x 0.9) = 2.65A
C11     Number of modules in series (A7 / C9) = 1
C12     Output per module (C10 x C6) = 13.2Ah
C13     Number of parallel strings of modules (C5 / C12) = 10.3

The battery capacity is, as has been already stated, the minimum
required to do the job.


It didn't go anywhere. Perhaps you mean the battery efficiency.
Already in the formula (C4)

0%. Actually I think that you mean Maximum allowable depth of
discharge (B2)

C10 is the correct charge rate.

See above

All of them

You talk a lot of nonsense Tweedledee.

None of your questions mean anything in relation to the minimum
battery capacity as stated. At (B9) you enter the battery capacity of
the battery you choose. You chose Trojan T105s at 225 ah. I put that
in the formula. The only thing that changed was the daily DoD. It fell
from 68% to 54%.

If there are any other parameters you wish to change, you know, like
removing the 20% to the daily load you insist should happen just after
you have adjusted the daily load to account for the inverter's
inefficiency, I will be happy to change the sample sizing.

This Thread
Bookmark this thread:
  • Subject
  • Author
  • Date
please rate this thread