Posted by *Ron Rosenfeld* on July 5, 2008, 11:55 am

On Thu, 3 Jul 2008 17:33:58 -0700 (PDT), bealiba@gmail.com wrote:

*>"so it's hard to speculate regarding storage"*

*>There is no speculation involved. If you know the daily load, which we*

*>do (122.55Ah), the battery is sized to meet this load.*

George is now adding mind-reading to his so-called talents.

He "knows" the OP will want *battery* storage, even though the OP did not

mention anything about the kind of storage that might be appropriate for

his application. And also that he will want only 1 day of autonomy to run

his pump daily.

But even with regard to this assumption of his, note that GG writes the

following:

GG: There is no speculation involved. If you know the daily load, which we

do (122.55Ah), the battery is sized to meet this load.

GG: it remains a straight forward calculation.

In a previous post, he figured one day of autonomy.

GG:

12V system

2250 Wh/day

1 Day autonomy

300Ah Battery

66% Daily DOD

5 PSH/Day

17- 50W Panels

In another post, he is also recommending one day of autonomy, but comes up

with a different sized battery:

GG:

B1 Number of days of autonomy = 1

B6 Adjusted battery capacity (B3 / B5) = 180.5

B9 A-hr capacity of selected battery = 180Ah

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

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

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

It seems GG's "straight forward calculation" can give different results

depending on ... whimsy?

Same pump; same number of days of autonomy; two very different sized

batteries?

--ron

Posted by *bealiba* on July 5, 2008, 1:35 pm

*> On Thu, 3 Jul 2008 17:33:58 -0700 (PDT), beal...@gmail.com wrote:*

*> >"so it's hard to speculate regarding storage"*

*> >There is no speculation involved. If you know the daily load, which we*

*> >do (122.55Ah), the battery is sized to meet this load.*

*> George is now adding mind-reading to his so-called talents.*

*> He "knows" the OP will want *battery* storage, even though the OP did not*

*> mention anything about the kind of storage that might be appropriate for*

*> his application. And also that he will want only 1 day of autonomy to run*

*> his pump daily.*

*> But even with regard to this assumption of his, note that GG writes the*

*> following:*

*> GG: There is no speculation involved. If you know the daily load, which we*

*> do (122.55Ah), the battery is sized to meet this load.*

*> GG: it remains a straight forward calculation.*

*> In a previous post, he figured one day of autonomy.*

*> GG:*

*> 12V system*

*> 2250 Wh/day*

*> 1 Day autonomy*

*> 300Ah Battery*

*> 66% Daily DOD*

*> 5 PSH/Day*

*> 17- 50W Panels*

*> In another post, he is also recommending one day of autonomy, but comes up*

*> with a different sized battery:*

*> GG:*

*> B1 Number of days of autonomy = 1*

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

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

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

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

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

*> It seems GG's "straight forward calculation" can give different results*

*> depending on ... whimsy?*

*> Same pump; same number of days of autonomy; two very different sized*

*> batteries?*

*> --ron*

Ron, you are telling a lie. Yes Same pump; same number of days of

autonomy;

Different number of Ahs. It seems that wayne is not the only one who

misquotes.

This is what was said;

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 c

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 = 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%

This is correct and everyone can follow the calculation step by step.

There is nothing hidden.

You're not fooling anybody.

Posted by *Ron Rosenfeld* on July 6, 2008, 2:48 am

On Sat, 5 Jul 2008 06:35:05 -0700 (PDT), bealiba@gmail.com wrote:

*>Ron, you are telling a lie. Yes Same pump; same number of days of*

*>autonomy;*

*>Different number of Ahs. It seems that wayne is not the only one who*

*>misquotes.*

George,

Since it was you who specified different battery sizes given the same

question by the OP, it is clear who is being disingenuous.

You know, if you spent a fraction of the time educating yourself and

researching your stuff as you do trying to cover up your errors, you might

actually learn something worthwhile.

What data source did you use to get your values for what seems to be your

most recent guess at an acceptable system (11 - 50Watt panels and a 180Ah

battery)?

The data I have for Kilauea show that for 50 watt panels with a NOCT of

45.2°C, temperature coeff of power of -0.5%/°C, and an efficiency of 13% at

STC, that your recommendation of 11 panels and 180AH of battery storage

will result in a shortened battery life and a significant capacity

shortage.

I didn't have the figures for your 180Ah battery, so I used Trojan T-105

which have a 225 Ah capacity, a minimum state of charge of 30% and an 85%

efficiency. However, to make it more compatible with your 180Ah battery, I

changed the efficiency to 90%.

With 11 panels and 2 "Ghio-modifed" T-105's in series, there is a capacity

shortage of 23% over the course of a year, and battery life is 42% of what

it would be with an optimal system. It is also more expensive than the

optimal system.

I suppose you will now try to explain how your 180Ah battery will prevent

the shortfall and have an improved battery life compared with a 225Ah

battery, that has the same allowable depth of discharge and efficiency. Or

maybe you'll just revert to type and continue with your insults <sigh>.

--ron

Posted by *bealiba* on July 6, 2008, 3:01 am

*> On Sat, 5 Jul 2008 06:35:05 -0700 (PDT), beal...@gmail.com wrote:*

*> >Ron, you are telling a lie. Yes Same pump; same number of days of*

*> >autonomy;*

*> >Different number of Ahs. It seems that wayne is not the only one who*

*> >misquotes.*

*> George,*

*> Since it was you who specified different battery sizes given the same*

*> question by the OP, it is clear who is being disingenuous.*

You told a lie and got caught.

*> You know, if you spent a fraction of the time educating yourself and*

*> researching your stuff as you do trying to cover up your errors, you might*

*> actually learn something worthwhile.*

I learned that you will misquote, quote out of context and tell

outright lies.

*> What data source did you use to get your values for what seems to be your*

*> most recent guess at an acceptable system (11 - 50Watt panels and a 180Ah*

*> battery)?*

Watts and panels from OP.

*> The data I have for Kilauea show that for 50 watt panels with a NOCT of*

*> 45.2C, temperature coeff of power of -0.5%/C, and an efficiency of 13% at*

*> STC, that your recommendation of 11 panels and 180AH of battery storage*

*> will result in a shortened battery life and a significant capacity*

*> shortage.*

Show us the numbers. OH, sorry, I forgot, you're an idiot and can't

prove any claim you might make

*> I didn't have the figures for your 180Ah battery, so I used Trojan T-105*

*> which have a 225 Ah capacity, a minimum state of charge of 30% and an 85%*

*> efficiency. However, to make it more compatible with your 180Ah battery, I*

*> changed the efficiency to 90%.*

Ah yes. The T105 Trojan, Trojan make condoms, don't they? Your amateur

status is showing.

*> With 11 panels and 2 "Ghio-modifed" T-105's in series, there is a capacity*

*> shortage of 23% over the course of a year, and battery life is 42% of what*

*> it would be with an optimal system. It is also more expensive than the*

*> optimal system.*

Show us the numbers. OH, sorry, I forgot, you're an idiot and can't

prove any claim you might make. Damn, I did it again.

*> I suppose you will now try to explain how your 180Ah battery will prevent*

*> the shortfall and have an improved battery life compared with a 225Ah*

*> battery, that has the same allowable depth of discharge and efficiency. Or*

*> maybe you'll just revert to type and continue with your insults <sigh>.*

180Ah is the correct capacity for the job. You have yet to prove it

wrong.

Posted by *bealiba* on July 6, 2008, 6:11 am

While we wait for ron's next tirade of nonsense let's see what happens

when we change the battery capacity to 225 Ahs.

Same formula, same data with the battery capacity changed to 225Ahs at

B9, which funnily enough is labeled "A-hr capacity of selected

battery". The reason for this label is that this is where "YOU" get to

specify the battery you choose to use. You see, while ron whinges

about the calculated minimum battery size, "YOU" get to specify "YOUR"

requirements within the formula. The only proviso is thet you do not

change any of the actual calculations.

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 c

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%

And there you have it, the Daily depth of discharge has dropped to

54.47%

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

This formula is correct and will correctly size a stand alone PV

system. Neither Tweedledee nor Tweedledum can prove otherwise. Of

course they will keep saying it is incorrect, but never a shred of

mathematical proof will ever be forthcoming.

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

>"so it's hard to speculate regarding storage">There is no speculation involved. If you know the daily load, which we>do (122.55Ah), the battery is sized to meet this load.