Posted by *bealiba* on July 10, 2008, 3:53 am

*> On Tue, 8 Jul 2008 23:24:21 -0700 (PDT), beal...@gmail.com wrote:*

*> >> On Sun, 6 Jul 2008 19:07:12 -0700 (PDT), beal...@gmail.com wrote:*

*> >> >Prove it. You claim a very precise 23% short fall. All you have to do*

*> >> >is show the numbers.*

*> >> That was for a hypothetical battery, which was proposed only because *you**

*> >> kept blathering on about battery recommendations, and misquoting (a kind*

*> >> way of saying "lying" about) my panel array recommendation size.*

*> >> With a hypothetical Trojan T105 battery (modified to 90% efficiency) in a*

*> >> 50 watt/panel, 11 panel system, that shortfall is predictable. I did not*

*> >> propose that it be used in the system; it was proposed only because you did*

*> >> not quote any particular battery or specifications other than the 180Ah*

*> >> battery figure, which you use for the 100 hr rating.*

*> >> >> B9 A-hr capacity of selected battery = 180Ah*

*> >> >> B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180*

*> >> That would mean that that your proposed battery can output a current of*

*> >> 1.8A for 100 hrs.*

*> >> You also claim that your battery has a*

*> >> >> C4 Battery efficiency = 90%*

*> >> and a*

*> >> >> B2 Maximum allowable depth of discharge = 70%*

*> >> I don't have a battery in my database that matches those specifications of*

*> >> yours. The closest is the Trojan T105 which has a capacity at the 20 hr*

*> >> rate of 225Ah, and so would obviously be better than 180Ah at the 100 hr*

*> >> rate. But its round trip efficiency is only 85%, vs the 90% in the battery*

*> >> you are quoting.*

*> >> Changing the efficiency to 90% in the specifications for the T105 and*

*> >> leaving everything else the same results in the simulation showing a 23%*

*> >> shortfall.*

*> >> But I thought you would want to specify your own battery, to get a more*

*> >> realistic result of your proposed 11 panel system with a 180Ah battery (at*

*> >> the 100 hr rate).*

*> >> If you are really interested in the simulation results of your proposed*

*> >> system with a hypothetical T105 modified to 90% efficiency, I could post*

*> >> that. But to what end -- that battery does not exist.*

*> >> I think the simulation would be of more value with a "real" battery that*

*> >> comes close to the parameters you are using. I could use the unmodified*

*> >> T105, which has a 27% shortfall (if I recall correctly, or any other real*

*> >> battery for which you can provide the specifications I mentioned.*

*> >> --ron*

*> >The battery size given in the calculation is the minimum capacity*

*> >required to run the stated pump for 30 minutes. The calculation allows*

*> >you the choose a battery.*

*> It seems you will not (or cannot) specify a practical battery to use in*

*> this application that matches the inputs you used in your spreadsheet.*

*> I must say that doesn't surprise me, although I was hopeful of finding a*

*> battery with a 90% efficiency, a flat current vs capacity curve in the 30*

*> min to 100 hr range, along with an acceptable life when limited to 70%*

*> maximum DOD.*

*> If your system is going to work, your 180Ah capacity battery at the 100 hr*

*> rate -- 1.8A, must also have the *same* capacity when putting out 245A for*

*> the 1/2 hour that the pump will be running!*

*> C'mon George, what kind of a battery is this? If you can't supply the*

*> battery you specified, your system is pretty worthless.*

*> --ron*

As I have already pointed out it is a recommendation for minimum

battery capacity and not a recommendation for a particular battery.

But as you asked, the total removed from the battery would be 122.5Ah

from 180Ah storage in half an hour. Which is as close as you can get

with only the recommendation for minimum battery capacity.

On the other hand "YOU" have recommended a very definite 28 Amps of 12

Volt panels to run a 230 Volt, 2500 Watt pump and specified no

batteries and no spreadsheet. As you do not want the batteries or the

spreadsheet why do you keep harping back to them?

This is your second post in a day where you have failed to answer the

question of how 10 panels at 28 Amps total will run 2500 Watts of pump

without batteries.

Why is no one surprised?

Posted by *Ron Rosenfeld* on July 11, 2008, 10:47 pm

On Wed, 9 Jul 2008 20:53:42 -0700 (PDT), bealiba@gmail.com wrote:

*>This is your second post in a day where you have failed to answer the*

*>question of how 10 panels at 28 Amps total will run 2500 Watts of pump*

*>without batteries.*

*I* never claimed that it would. Your "straw-man" technique of debating is

pretty transparent, George.

You, on the other hand, have posed at least three systems which you claim

would work -- but none of them will work reliably 24/7.

--ron

Posted by *Ron Rosenfeld* on July 11, 2008, 11:17 pm

On Wed, 9 Jul 2008 20:53:42 -0700 (PDT), bealiba@gmail.com wrote:

*>As I have already pointed out it is a recommendation for minimum*

*>battery capacity and not a recommendation for a particular battery.*

*>But as you asked, the total removed from the battery would be 122.5Ah*

*>from 180Ah storage in half an hour. Which is as close as you can get*

*>with only the recommendation for minimum battery capacity.*

Yes, but you have failed to recommend a battery that meets the

specifications that you put into your useless spreadsheet.

In your useless spreadsheet, you specified a minimum battery capacity of

180Ah at the 100 hr rate. Now you are writing that this battery will also

have a capacity of 180Ah at the 30 minute rate.

But you remain unwilling to specify a real world battery that would have

those characteristics, along with the 90% efficiency and 30% maximum DOD

that you also specified in your useless spreadsheet.

Did you just make up some imaginary battery specifications, George, or do

you really know of a battery that has the same capacity at its 100hr rate

as it does at its 30 minute rate, along with a 90% efficiency and a 30%

maximum DOD?

For those who might be following along but not cognizant of battery

characteristics, the problem here is that the usual lead-acid battery may

have a capacity, at its 30 minute rate, of maybe 20% of the capacity at the

100 hr rate. Since George is specifying a battery in his spreadsheet that

has a capacity of 180Ah at the 100 hr rate, its capacity at the rate that

must be used in this system is only going to be maybe 35Ah.

*Unless* there is something special about the battery which George is

unwilling to disclose.

Clearly, George, your knowledge of battery current vs capacity curves is

fairly limited. But you could probably research Peukert for some

information about this factor.

Here's what you entered into your useless spreadsheet, with regard to the

battery you are recommending for this system:

B1 Number of days of autonomy = 1

B2 Maximum allowable depth of discharge = 70%

B6 Adjusted battery capacity (B3 / B5) = 180.5

B7 Selected Battery

B8 Selected battery discharge rate 100

B9 A-hr capacity of selected battery = 180Ah

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 = 180

B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180

B14 Daily depth of discharge (100 x A8 / B13) = 68%

C4 Battery efficiency = 90%

So far, you've made a number of errors in trying to design for the OP's

system, even with your last attempt.

1. You specified your battery incorrectly, specifying a 100 hr rate to

determine the capacity instead of the 30 minute rate which you should have

been using.

Although your message above seems to indicate that you finally understand

that, you show no evidence of understanding that a battery with a 180Ah

capacity at the 30 minute rate might have as much as a 1200 Ah

capacity at the 100 hr rate you entered into your useless spreadsheet.

And you have been unable to specify a real battery that does have the

characteristics of the one you entered.

2. You have assumed that 1 day of autonomy will be sufficient at the OP's

location.

3. You have assumed that the OP requires battery storage.

4. You have accused me of oversizing the array, when, even your last

attempt, is for a system that includes 11 panels vs the 10 panels I

recommended.

5. You have attempted to shoehorn my recommnedation for array sizing into

your useless spreadsheet in an attempt to convince yourself that my panel

array size recommendation somehow means an inappropriate battery size. And

even there, you still used the same, incorrect, 100 hr capacity figure.

6. You have used an inappropriate daily temperature figure for the

OP's location.

*> B4 Lowest 24 hour average temperature c*

7. You seem to have specified the OP's panel incorrectly

OP: Assume for instance the panels are 50 watt, 17 vdc, 2.94 amp

So GG enters into his spreadsheet:

C8 Selected module I at 14 volts at NOCT 2.94A

which equates to about a 41 watt panel. You then apply various corrections

to this number, to further reduce its output.

You've been at this game long enough that you should have learned how not

to make these simple errors, or to correct them promptly if you do.

It is sad, but clearly you have not advanced since 1999 when Nick Pine

wrote about you: "Who would hire this PV nitwit?"

--ron

--ron

Posted by *bealiba* on July 12, 2008, 12:33 am

*> On Wed, 9 Jul 2008 20:53:42 -0700 (PDT), beal...@gmail.com wrote:*

*> >As I have already pointed out it is a recommendation for minimum*

*> >battery capacity and not a recommendation for a particular battery.*

*> >But as you asked, the total removed from the battery would be 122.5Ah*

*> >from 180Ah storage in half an hour. Which is as close as you can get*

*> >with only the recommendation for minimum battery capacity.*

*> Yes, but you have failed to recommend a battery that meets the*

*> specifications that you put into your useless spreadsheet.*

No, not failed. 180Ah is the correct minimum required. The actual

battery to be chosen. You clearly stated that you didn't want a

battery included so why are you crying now?

*> In your useless spreadsheet, you specified a minimum battery capacity of*

*> 180Ah at the 100 hr rate. Now you are writing that this battery will also*

*> have a capacity of 180Ah at the 30 minute rate.*

No. 180AH is the correct minimum required. This minimum must be met or

exceeded by the actual battery chosen with the chosen batteries

parameters entered.

*> But you remain unwilling to specify a real world battery that would have*

*> those characteristics, along with the 90% efficiency and 30% maximum DOD*

*> that you also specified in your useless spreadsheet.*

Lying about the numbers is the hallmark of a shyster. The Maximum DOD

is clearly stated as 70%. This leaves 30% remaining in the battery.

*> Did you just make up some imaginary battery specifications, George, or do*

*> you really know of a battery that has the same capacity at its 100hr rate*

*> as it does at its 30 minute rate, along with a 90% efficiency and a 30%*

*> maximum DOD?*

Lying about the numbers is the hallmark of a shyster. The Maximum DOD

is clearly stated as 70%. This leaves 30% remaining in the battery.

*> For those who might be following along but not cognizant of battery*

*> characteristics, the problem here is that the usual lead-acid battery may*

*> have a capacity, at its 30 minute rate, of maybe 20% of the capacity at the*

*> 100 hr rate. Since George is specifying a battery in his spreadsheet that*

*> has a capacity of 180Ah at the 100 hr rate, its capacity at the rate that*

*> must be used in this system is only going to be maybe 35Ah.*

George did not at any point recommend a battery. In fact Tweedledee is

the only one to recommend a battery, T105 Trojan.

*> *Unless* there is something special about the battery which George is*

*> unwilling to disclose.*

*> Clearly, George, your knowledge of battery current vs capacity curves is*

*> fairly limited. But you could probably research Peukert for some*

*> information about this factor.*

*> Here's what you entered into your useless spreadsheet, with regard to the*

*> battery you are recommending for this system:*

*> B1 Number of days of autonomy = 1*

*> B2 Maximum allowable depth of discharge = 70%*

*> B6 Adjusted battery capacity (B3 / B5) = 180.5*

*> B7 Selected Battery*

It will be noted that B7 is blank. This is because I have not

recommended a battery.

*> B8 Selected battery discharge rate 100*

B8 requires information from user about chosen battery

*> B9 A-hr capacity of selected battery = 180Ah*

B8 requires information from user about chosen battery

*> 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 = 180*

*> B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180*

*> B14 Daily depth of discharge (100 x A8 / B13) = 68%*

*> C4 Battery efficiency = 90%*

*> So far, you've made a number of errors in trying to design for the OP's*

*> system, even with your last attempt.*

This is the correct formula for the sizing of standalone PV systems.

It requires user input.

*> 1. You specified your battery incorrectly, specifying a 100 hr rate to*

*> determine the capacity instead of the 30 minute rate which you should have*

*> been using.*

User input required.

*> Although your message above seems to indicate that you finally understand*

*> that, you show no evidence of understanding that a battery with a 180Ah*

*> capacity at the 30 minute rate might have as much as a 1200 Ah*

*> capacity at the 100 hr rate you entered into your useless spreadsheet.*

180 Ah is the minimum required.

*> And you have been unable to specify a real battery that does have the*

*> characteristics of the one you entered.*

I have not specified a battery.

*> 2. You have assumed that 1 day of autonomy will be sufficient at the OP's*

*> location.*

Oh dear. you need to learn that when you are up to your ass in shit

and sinking fast you should not put your foot in your mouth.

I in fact am on record as saying:

Of course there is still the problem of designing for an autonomy of

only one day. It is more common to design for several days autonomy.

So let's up the ante and change the system for 5 days autonomy. We

will keep the Trojans so we can clearly see the change;

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 = 5

B2 Maximum allowable depth of discharge = 70%

B3 Battery capacity (A8 x B1 / B2) = 875.35Ah

B4 Lowest 24 hour average temperature c

B5 Temperature correction factor =.97

B6 Adjusted battery capacity (B3 / B5) = 902.42

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) = 4

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) = 900

B14 Daily depth of discharge (100 x A8 / B13) = 13.62%

C1 Design tilt

C2 Design month

C3 Total energy demand per day (A8) 2.55Ah

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

*> 3. You have assumed that the OP requires battery storage.*

Ah yes. 28 Amps of panels at 12 volts to run a 2500 Watt pump at

230Volts without batteries. Why don't you explain how this works.

*> 4. You have accused me of oversizing the array, when, even your last*

*> attempt, is for a system that includes 11 panels vs the 10 panels I*

*> recommended.*

*> 5. You have attempted to shoehorn my recommnedation for array sizing into*

*> your useless spreadsheet in an attempt to convince yourself that my panel*

*> array size recommendation somehow means an inappropriate battery size. And*

*> even there, you still used the same, incorrect, 100 hr capacity figure.*

*> 6. You have used an inappropriate daily temperature figure for the*

*> OP's location.*

*> > B4 Lowest 24 hour average temperature c*

*> 7. You seem to have specified the OP's panel incorrectly*

*> OP: Assume for instance the panels are 50 watt, 17 vdc, 2.94 amp*

*> So GG enters into his spreadsheet:*

*> C8 Selected module I at 14 volts at NOCT 2.94A*

Which is the correct information.

*> which equates to about a 41 watt panel. You then apply various corrections*

*> to this number, to further reduce its output.*

*> You've been at this game long enough that you should have learned how not*

*> to make these simple errors, or to correct them promptly if you do.*

*> It is sad, but clearly you have not advanced since 1999 when Nick Pine*

*> wrote about you: "Who would hire this PV nitwit?"*

Ah yes, good old nick. The man who can barly get his porch light to

work on solar, the inventor of the solar garage. How many of those do

you think he has sold?

*> --ron*

*> --ron*

Tweedledee said:

*> AC Load 2500W x 0.5hrs/day --> 1250 watt-hrs/day*

*> Inverter Efficiency 85%*

*> Adjusted AC Load 1471 Watt-hrs/day*

*> Nominal system voltage 12V (This is appropriate for your panels)*

*> Total load in AH 123 amp-hrs per day*

*> System Losses, etc 20%*

*> Total Required 147 amp-hrs per day*

*> Worst month insolation 5.08 kWh/m^2 per day (effective full sun hours)*

*> Required array current 28.95A (total/insolation)*

*> Numbe of panels 28.95/2.94 --> 9.85 --> 10 panels*

-----------------------------------

And he is very adamant about;

*> Nothing in there about batteries.*

*> Nothing in there about using your spreadsheet or any of your calculations.*

So no batteries, no spreadsheet. And 28 Amps of panels at 12 Volts

will not run a 2500 Watt - 230 Volt pump.

All of a sudden Tweedledee wants to talk about Batteries and

Spreadsheets, funny that.

Posted by *Ron Rosenfeld* on July 12, 2008, 3:35 am

On Fri, 11 Jul 2008 17:33:53 -0700 (PDT), bealiba@gmail.com wrote:

*>> But you remain unwilling to specify a real world battery that would have*

*>> those characteristics, along with the 90% efficiency and 30% maximum DOD*

*>> that you also specified in your useless spreadsheet.*

*>Lying about the numbers is the hallmark of a shyster. The Maximum DOD*

*>is clearly stated as 70%. This leaves 30% remaining in the battery.*

You're correct George. I made a typo in quoting your data. I wrote 30%

maximum DOD when I should have written 30% SOC or 70% DOD.

But you still can't specify a battery that meets *your* specifications of

180Ah at 100 hr rate

90% efficiency

70% maximum DOD

and will also have a capacity of 180Ah at its 30 minute rate.

You can make up imaginary specifications all you want, but if you can't

produce a battery that meets them, or even comes close, your specifications

are useless.

You probably don't realize that a battery with a 180Ah capacity at its 100

hr rate, as you specify in your useless spreadsheet, will have a *much*

lower capacity at its 30 minute rate.

And you can't even read, comprehend, or debate intelligently. Your tactic

of taking phrases out of context, deliberately misunderstanding what was

written, name-calling, false attributions, and the like, of which you are

guilty, are the true signs of a shyster: "A person who gets along by

petty, sharp practices".

Thanks for the entertainment, George. But I'm tired of dealing with your

name-calling and childish techniques.

By the way, I think your final attempt of 11 panels and 8 T105 batteries

should work at the OP's location. (The T105 is a 6V battery, so I adjusted

your calculation accordingly).

Of course, a system of 10 panels and 4 T105's would also work, with a

minimum SOC of 40% during the winter months, and no less than 50% the rest

of the year. So your system would have 10% more panels and twice as many

batteries as is necessary to run this system using battery storage with a

goal of no energy shortfall.

One could use more expensive batteries to reduce the number of strings from

your 4 or my 2 to just one, but you'd have to look closely at the

trade-offs, both economic and in maintenance.

--ron

> On Tue, 8 Jul 2008 23:24:21 -0700 (PDT), beal...@gmail.com wrote:> >> On Sun, 6 Jul 2008 19:07:12 -0700 (PDT), beal...@gmail.com wrote:> >> >Prove it. You claim a very precise 23% short fall. All you have to do> >> >is show the numbers.> >> That was for a hypothetical battery, which was proposed only because *you*> >> kept blathering on about battery recommendations, and misquoting (a kind> >> way of saying "lying" about) my panel array recommendation size.> >> With a hypothetical Trojan T105 battery (modified to 90% efficiency) in a> >> 50 watt/panel, 11 panel system, that shortfall is predictable. I did not> >> propose that it be used in the system; it was proposed only because you did> >> not quote any particular battery or specifications other than the 180Ah> >> battery figure, which you use for the 100 hr rating.> >> >> B9 A-hr capacity of selected battery = 180Ah> >> >> B13 Capacity of battery bank at 100 hr rate (B12 x B10) = 180> >> That would mean that that your proposed battery can output a current of> >> 1.8A for 100 hrs.> >> You also claim that your battery has a> >> >> C4 Battery efficiency = 90%> >> and a> >> >> B2 Maximum allowable depth of discharge = 70%> >> I don't have a battery in my database that matches those specifications of> >> yours. The closest is the Trojan T105 which has a capacity at the 20 hr> >> rate of 225Ah, and so would obviously be better than 180Ah at the 100 hr> >> rate. But its round trip efficiency is only 85%, vs the 90% in the battery> >> you are quoting.> >> Changing the efficiency to 90% in the specifications for the T105 and> >> leaving everything else the same results in the simulation showing a 23%> >> shortfall.> >> But I thought you would want to specify your own battery, to get a more> >> realistic result of your proposed 11 panel system with a 180Ah battery (at> >> the 100 hr rate).> >> If you are really interested in the simulation results of your proposed> >> system with a hypothetical T105 modified to 90% efficiency, I could post> >> that. But to what end -- that battery does not exist.> >> I think the simulation would be of more value with a "real" battery that> >> comes close to the parameters you are using. I could use the unmodified> >> T105, which has a 27% shortfall (if I recall correctly, or any other real> >> battery for which you can provide the specifications I mentioned.> >> --ron> >The battery size given in the calculation is the minimum capacity> >required to run the stated pump for 30 minutes. The calculation allows> >you the choose a battery.> It seems you will not (or cannot) specify a practical battery to use in> this application that matches the inputs you used in your spreadsheet.> I must say that doesn't surprise me, although I was hopeful of finding a> battery with a 90% efficiency, a flat current vs capacity curve in the 30> min to 100 hr range, along with an acceptable life when limited to 70%> maximum DOD.> If your system is going to work, your 180Ah capacity battery at the 100 hr> rate -- 1.8A, must also have the *same* capacity when putting out 245A for> the 1/2 hour that the pump will be running!> C'mon George, what kind of a battery is this? If you can't supply the> battery you specified, your system is pretty worthless.> --ron