Maker Pro
Maker Pro

Formula for PV Panels and Inverter

S

Steve Spence

Jan 1, 1970
0
SolarFlaire said:
What did I tell you about Wayne's alter ego?


LOLOLOLOL. Right on cue


You are confused. Wayne has no alter ego.
 
D

daestrom

Jan 1, 1970
0
SolarFlaire said:
Can't you send me your copy, Taz...oooops I mean Tazoar
or Gymmy Bob or whatever you use du jour.

Nice try Gymmy Bob, Solar Flare, Solar Flair, etc...

We can easily recognize the *real* 'Gymmy Bob', Bengi, Benji, Flare,
Flaire.....

Trying to accuse someone *else* of your past transgressions?? How lame!!!

daestrom
 
D

daestrom

Jan 1, 1970
0
SolarFlaire said:
What did I tell you about Wayne's alter ego?


LOLOLOLOL. Right on cue

Silly attempt to 'change reality'???

We all recognize your various re-incarnations very easily. And now you try
and make people think that those past identities that you've used (and
disgraced) weren't really you, but Wayne.

So transparent. So lame.

daestrom
 
W

wmbjk

Jan 1, 1970
0
Only one of george's sock puppets would consider this a victory for
george.

If George has ever used a sock puppet, I didn't notice it. Now Gymmy
Bob on the other hand uses so many names he can't keep them all
straight. But George did glom right onto Gymmy's troll list BS even
though it included the names of several regulars. That was low and
transparent even for him. They need to coordinate their stories a
little better - they've both claimed that I'm a roving phantom, and
that you and I and a bunch of others are all the same person. And yet
George claims to have actually been to my place. I wonder how he made
the decision to head for Arizona instead of New York? :) It's too
funny, even though they both think the other is an idiot (the one
thing they got right), they teamed up anyway, each hoping to take
advantage. And both lost further credibility because of the
partnership. It's a perfect example of nitwit karma.

Wayne
 
W

wmbjk

Jan 1, 1970
0
message


Poor troll Dick head.

4.8 out of 10

I'm thinkin' that Gymmy could tell us exactly how many seats are on a
short school bus...

Reminds me of a joke -

Gymmy's class is learning to count in school, and he finds he can
count to 100 even though all the other students can only get to 9.
When he tells his mom she says "that's because you're a Usenet troll".

Next day the kids are learning the alphabet, and Gymmy reports to mom
that he can recite the whole thing while the other students can't get
past C. Mom says it's because he's a Usenet troll.

Third day the students are comparing height, and Gymmy tells mom he's
the tallest. "Is that because I'm a Usenet troll mom?" Mom says, "no,
it's because you're 27."

Wayne
 
D

daestrom

Jan 1, 1970
0
SolarFlaire said:
Sounds like you have some intimate relationship with
this super troll also.

Oh come on, surely you can do better than that???

As for 'intimate relations', whats the matter, not 'getting any'??

daestrom
 
W

wmbjk

Jan 1, 1970
0
Oh come on, surely you can do better than that???

As for 'intimate relations', whats the matter, not 'getting any'??

daestrom

It's hard to imagine who'd be willing to give him any. But the name
Flaire at least suggests what he's looking for.... Now he's changed it
to Flair. My crystal ball says that the newest name will be in all the
same kill filters before long.

Wayne
 
G

George Ghio

Jan 1, 1970
0
The Formula

Yes Martha there is a formula for designing solar power systems.

There has been a lot of controversy in these groups about this formula
for system sizing so let’s take a close look at the formula.

Step 1) Is the system volts. Usually 12, 24, 48 volts. See note (A) below.

Step 2) Is the battery volts. Now to be perfectly clear you may be using
a battery (several cells in one container) or a series of individual
cells to make a battery. See note (A) below.

Step 3) Is your daily load for the AC side of your system. This is in
Watt hours. See note (B) below.

Step 4) Is the inverters efficiency. This is needed because the
inverter, as well as providing AC for your use also consumes DC energy.
This is expressed as 0.9 for 90% - 0.85 for 85% etc.. See note (C) below

Step 5) Is where you account for the inverters inefficiency. The
calculation is (step 3 / step 4)

Step 6) Is the daily load for the DC side of your use if any.

Step 7) Is the total Ah demand for the day. The calculation is (step 5
+ step 4 / step 1) What we have done here is to add the AC Watt hours
(adjusted for the inverters inefficiency) to the DC watt hours (if
any)divided by the system voltage to produce the Amp hours these loads
will consume from our batteries.

Step 8) Is where we enter the number of days of autonomy required from
our system. This is the numbers of days the system must run without
input. Five days is common. See note (D) below.

9) Is the maximum depth of discharge for our battery. This is
expressed as 0.7 for 70% - 0.8 for 80% etc.. See note (E) below.

Step 10) Is where the basic battery capacity is calculated. The formula
is (step 7 x step 8 / step 9). What we have done here is to multiply the
total Amp hour demand per day by the days of autonomy and dividing the
result by the maximum allowable depth of discharge. See note (C) below.

Step 11) Is the lowest 24 hour average temperature in degrees Celsius.

Step 12) Is the correction factor. See note (F) below.

Step 13) Is where we adjust the battery capacity for the lowest 24 hour
average temperature. The formula is (step 10 / step 12).

Step 14) Is the Amp hour capacity of the battery chosen. See note (G) below.

Step 15) Is the number of batteries in parallel. The formula is (step 13
/ step 14) This is rounded up or down to a whole number. See note (A) below

Step 16) Is the number of batteries in series. This is rounded up or
down to a whole number. The formula is (step 1 / step 2)

Step 17) Is our daily Depth of Discharge. The formula is (100 x {step 7
/ step 14}) This is expressed as a percentage. The daily DoD should not
be confused with the Maximum DOD used at step 9.

Step 18) Battery effciency. A battery in good condition will be close to
90% so we will use 0.9 here. If you know that your battery is more or
less efficient than 90%, adjust this number accordingly.

Step 19) Is where we work out the array output required to for the
system to operate correctly. The formula is (step 7 /step 18)

Step 20) Is the Peak Sun Hours for the tilt of your panels for the month
that corresponds to mid winter where you are. This is the worst case.

Step 21) Is where we select a PV module. We look at the spec sheet and
find the module's Amps at 14V NOCT (Normal Operating Cell Temperature)
See note (H) below.

Step 22) Is the selected module's nominal voltage. Usually 12 or 24 Volts.

Step 23) Is the guaranteed current. The formula for this is (step 22 x 0.9)

Step 24) Is the number of panels in series. The formula is (step 1 /
step 20)

Step 25) Is the output per module. The formula for this is (step 23 x
step 20)

Step 26) Is the number of panels in parallel. The formula for this is
(step 19 / step 25)


NOTES:

A. Given that you should avoid the use of parallel strings of batteries
if possible you might find it advisable to go to a higher battery
voltage. Example; if If you size your system at 12V and find that the
only way to achieve the required Amp hour capacity is to use parallel
strings of batteries you may find that opting for a 24V system will
allow you to use a single string of batteries in series. This would be
the better option.



B. Why not use an average of week/month/year? Because an average is
lower than what you could/might use in a day. Average numbers = average
systems and average performance. The formula was written for daily load.
You can average separate loads. i.e. Dishwasher used every second day,
this load could be divided by 2 for daily load.


C. Not all inverters are 90% efficient. Many of the cheaper brands can
be as low as 60% efficient. A lot of inverters may only be 90% efficient
for a narrow part of their output. Get the full specs when ever
possible. Query the manufacturer for the efficiency curve. Beware the
words, "This twenty-nine dollar inverter is just as good as the one
costing three times more". Do your homework.



D. If you want to use 50% of your batteries capacity in a single day, as
has been suggested by some in these groups, then you will need to put
"1" as your days of autonomy. You will also need to replace 50% of your
batteries capacity + at least 10% every day. This means lots of panels
or a generator. There are people here who have convinced themselves that
they have a generator as a back up for charging. What they really have
is a generator system with solar boost.

This is a good point to talk about reality.

People have the amazing ability to lie to themselves. They do this as an
ego boosting exercise. Take the person who wants what their neighbour
has, but is too much of a cheap ass to buy it. He goes to Wall Mart and
pays a tenth of the price for a copy made in China.
The product has a tenth of the quality of the product the neighbour
has but our wanker can only see that his sad copy is better than the
real item his neighbour owns. Beware of falling into this trap. If you
can't afford to buy the best quality, accept the fact. Buy the best you
can. But you have lost the plot when you build a system that is based on
a generator with solar backup and start telling people that you live on
solar energy.



E. Many people get confused about "Maximum Depth Of Discharge" and daily
"Depth of Discharge". These are not the same thing. The Maximum Depth Of
Discharge is the absolute minimum state of charge you will allow your
batteries to reach. Some here will tell you that 50% is the limit, they
claim that discharging below this point will shorten the life of your
batteries.

These people fail to take into account that even if you set the limit at
80% a properly designed system will only reach this point a couple of
times a year.

They will also have you believe that discharging your batteries 50%
daily will give a longer battery life or more energy storage or some
other miraculous benefit.

The thing is though, is that you are designing a system to provide a
daily load with a certain number of Days of Autonomy from batteries of a
defined capacity.

If you set the Max DOD to a limit of 50% then you will be drawing your
Days of Autonomy from only 50% of your batteries capacity.

What difference does that make?

Well if we start with 12V system and a 2 kWh daily load and use 70% as
the max DOD with 5 days autonomy you will need a battery bank with a
capacity of 1377 Amp hours.

The same system with a maximum DOD of 50% would require a battery bank
with a capacity of 1929 Amp hours. And if we take it to the extreme, as
one person has suggested, of 20% DOD the battery capacity jumps to 4822
Amp hours.

So what these people will say.

I say cash, your cash to be more precise. 1377 Amp hours in L16 Trojans
would cost $3300 here in OZ.

1929 Ah in L16 Trojans adds another $1000 to the cost,

4822 Ah in L16 Trojans would cost $12100.

The life time difference between a Maximum Depth Of Discharge of 70% and
a Maximum Depth Of Discharge of 50%, given that this level of discharge
will only happen a couple of times a year in a properly designed system,
just might be measured in a days if not in hours.

The question is "Is an extra couple days of battery life worth an extra
$1000 for batteries?"



F. TEMP. Conversion factors

-10 .85criteria
-5 .88
0 .91
5 .94
10 .96
15 .97
20 .99
25 1.00


G. Yes, you have to choose a battery at this point. This means doing
your home work. Battery specs vary a lot between manufacturers. The
advertising is not the same as a spec sheet. Collect as many spec sheets
as you can. Try all your batteries in the formula. Keep copies of all
your trial calculations for comparison. Cost all your copies.



H. Yes, you have to choose a solar panel at this point. This means doing
your home work. Panel specs vary a lot between manufacturers. The
advertising is not the same as a spec sheet. Collect as many spec sheets
as you can. Try all your panels in the formula. Keep copies of all
your trial calculations for comparison. Cost all your copies.




This formula has been around for at least 25 years and has been used to
design working, balanced solar power systems for all this time.

There are any number of people in these NGs that think that because they
have managed to get batteries to charge from a solar panel that they
have designed a system.

The truth is that it is almost impossible to fail. But true design means
that the system will fulfill a set of criteria. Anything else is just
playing with solar.

Some just resort to copying a system. Then brag about their "Design".

Some just guess. Then brag about their "Design".

Some will buy some batteries and panels, but don't believe solar works
so they rely on a generator to make it work. Then brag about their
"Design".

The one thing they all have in common is a complete lack of
understanding of what they are doing.

They all say that this formula is only good for playing "what if" with
the numbers. It is true that you can play what if with this formula. But
it is also true that this formula will correctly size a solar power
system to meet your needs. There is no magic, no black art, just the
information you put into the blanks. It is entirely in your hands. You
can "Play" with solar or you can get serious about it.

If you are serious about it, if you want a system that will provide
your energy needs for many years, you need correct information for the
formula. It has to be the correct information.

Not correct because you want it to be correct. Not correct because it's
cheaper. Not correct because it makes you feel good. Not correct because
anything else will show the world that you are a complete git.

It has to be correct because it's true.

Now the usual suspects will flood you with reasons why this formula will
not work, or tell you that their system is so revolutionary that it is
beyond this formula and your comprehension.

They are wrong.

You can prove it yourself.

Want a nice clean spreadsheet of this formula?

[email protected]
 
W

wmbjk

Jan 1, 1970
0
The Formula

<snipped>

George, where is the step in "The Formula" where one calculates the
largest combination of loads and chooses a suitable inverter to power
them? Why do you continue to ignore such a fundamental concept, yet
always find time to focus on the specter of 60% efficient inverters?
Why should others be on their guard against these when you've
repeatedly failed to provide a single example?

Perhaps your dissertation was an attempt to rehabilitate your rep. Do
you really believe that all those slimy mischaracterizations are going
to help with that? Or were they the main reason for writing?

Wayne
 
G

George Ghio

Jan 1, 1970
0
Usual suspect # one.

This suspect maintains that his system is so advanced that no one in
these groups can comprehend it.

Here is a run-down.

Claims two days autonomy for his system with reduced load.

Fact: Reduction is 33% or 4950Wh out of a claimed 15kWh daily load.

Claims seven days autonomy when house is unoccupied.

Fact: Daily load for unoccupied house - 2880 Wh.

Claims to have designed his system.

Fact: Pulled his web site because he could not prove his numbers.
 
W

wmbjk

Jan 1, 1970
0
You could have chosen to ignore the troll George and be
a man.

He *did* ignore simple questions as always, which is what makes him a
coward like you.

He might learn someday that he'd be miles ahead to answer fair
questions rather than laying down a smokescreen of repetition and
absurd allegations. You might learn someday that if you'd stop
pretending then you wouldn't need to keep changing nyms. You both
might learn that a single photo is worth more than a thousand BS
posts. And we all might learn that Michael Jackson has never had
plastic surgery.

Wayne
 
W

William P.N. Smith

Jan 1, 1970
0
SolarFlare said:
Unlike you, I do not have to impress everybody with
pictures

<Plonk> Time for a new nym, Sybil.
 
W

wmbjk

Jan 1, 1970
0
I do not have to impress everybody with
pictures

Actually, you do. By posting so much nonsense (such as crossposting to
alt.clueless yet again for instance) and changing nyms so often, I
doubt anyone believes you own anything solar beyond a pocket
calculator. You've claimed to have bought what, 1000W? Let's see it
Gymmy.

Wayne
 
W

wmbjk

Jan 1, 1970
0
George, please show us examples of quality
inverters that are 60% efficient or less.

Duane

..... and examples of salesmen claiming "this twenty-nine dollar
inverter is just as good as the one costing three times more", and
examples showing that PV "advertising is not the same as a spec
sheet".

Wayne
 
W

wmbjk

Jan 1, 1970
0
Where was your fall arrest device

Tell ya' what Gymmy, I'll post a photo of the very (tired) harness I
was wearing that day within minutes of seeing a picture of your PV.
IOW, you'll never see it. If anyone else wants to see it, just email
me.

Now, why do you keep crossposting this thread to alt.clueless? Is that
supposed to be some sort of troll accomplishment?

Wayne
 
G

George Ghio

Jan 1, 1970
0
Hi Duane

Perhaps you misread the note. I did not make any claims about quality
inverters being only 60% efficient.

To make it clear, what I said was:


C. Not all inverters are 90% efficient. Many of the cheaper brands can
be as low as 60% efficient. A lot of inverters may only be 90% efficient
for a narrow part of their output. Get the full specs when ever
possible. Query the manufacturer for the efficiency curve. Beware the
words, "This twenty-nine dollar inverter is just as good as the one
costing three times more". Do your homework.


The last three words are very good advice.

Perhaps you can show where it is stated that all inverters from all
manufacturers at any price are 90% efficiency or better.

My advice would be that if a manufacturer does not provide full specs
then one would be very wise to view the manufacturer's advertising as
suspect.

You might look at

<http://www.selectronic.com.au/inverter/se22.html>

<http://www.selectronic.com.au/inverter/ps1/index.html>

<http://www.selectronic.com.au/inverter/se42.html>

to get a feel for efficiency curves.

Picking an inverter is much moor than just picking one that is "X"
efficient.

Is "X efficiency" in line with you loads?

Surely, if your load is between 1kw and 2kW for most of the of the day
you would want an inverter that was most efficient over this load.

The truth is, sadly, that many people make their purchases entirely on
price while telling themselves that what they bought is the best quality.
 
G

George Ghio

Jan 1, 1970
0
Ok Wayne, as you seem to think that I am somehow cheating it works like
this;

STEP 1) Define all your loads. Item - Watts - Time (YES, every single
one of them)

STEP 2) Will be addressed when you post your loads. (YES, every single
one of them).

Before you start crying about how unfair it is, remember this, I know
where you live. I know you have a surfeit of sun light hours. I know you
have some loads that others do not. I know that your system will not be
an average system. You will end up with a properly defined system.

P.S. I'm not holding my breath
 
W

wmbjk

Jan 1, 1970
0
Perhaps you misread the note. I did not make any claims about quality
inverters being only 60% efficient.

George, you've repeatedly claimed that folks need be on guard against
60% efficient inverters. And you've repeatedly been asked to provide
examples of those. The fact that you haven't done so makes it pretty
clear that you don't know of any such inverters. So why do you keep
embellishing your comments about inverter efficiency? And what's with
this $29 versus $79 inverter thing? In what real-world home-power
system planning process is anyone shopping for such inverters?
Surely, if your load is between 1kw and 2kW for most of the of the day
you would want an inverter that was most efficient over this load.

Of course everyone "wants" the *best* efficiency. But that is
sometimes going to be trumped by the fact that the inverter **must**
be able to support the largest regular load combinations.

Anyway, why are you so focused on inverter inefficiency, but silent on
other topics that are much more likely to be an issue for most, such
as the advantages of built-in chargers, search mode, and idle draw, or
allowing for Puekert's exponent and lost production due to charge
controller throttling? I can't remember you mentioning any of those
considerations in your numerous dissertations. It appears that your
only priorities are parameters you can fit into your own spreadsheet.
The truth is, sadly, that many people make their purchases entirely on
price while telling themselves that what they bought is the best quality.

Can you provide any examples of this? Or show some low-cost products
that you think buyers believe are "best quality"? I don't think you
can, and it seems to me that your habit of conjuring imaginary dragons
to slay is getting worse.

Wayne
 
W

wmbjk

Jan 1, 1970
0
I know
where you live. I know you have a surfeit of sun light hours. I know you
have some loads that others do not. I know that your system will not be
an average system. You will end up with a properly defined system.

You *know* all these things? Very well then, you shouldn't have any
trouble showing us an example of *exactly* what you'd do with one of
my many discretionary loads.

This morning I ran the heat pump (700W load, 24V system) in the office
for an hour. Prior to that, no heat pump had been run for about 10
days (warm winter), and I don't know when one will be needed next,
which means that neither do you. So, please "properly define" for us
that load's energy consumption, and describe how much PV and battery
capacity you'd allow for it. Pretend the inverter is 100% efficient,
and don't bother trying to evade or complicate the question by putting
up a smokescreen of irrelevant questions and minutiae. And keep in
mind that you wrote only recently that you don't believe in averaging
loads over any period longer than two days.
P.S. I'm not holding my breath

Neither am I, your debating tactics seem pretty much limited to
diversion, bluster, and BS these days. Was there ever a time when you
could answer a simple question or back up any of your foolish
assertions? Probably not.

Wayne
 
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