Maker Pro
Maker Pro

Learning the difference

G

George Ghio

Jan 1, 1970
0
June 15, 2007
The danger of solar power information, and indeed information for any other pursuit, from the web
and/or news groups is a combination of self delusion, self aggrandizement and greed.

SELF DELUSION; This is a big trap for for many people. It works like this, a person decides that he
would like to use solar power. This person has a preconceived idea of solar power based on what they
have been told by someone in a pub, seen on TV or just wishful thinking. It really doesn’t matter
where the info comes from. What matters is that it is, nine times out of ten, utter nonsense. The
problem is that the person wants to believe this information. Why do they want to believe what is
patently rubbish. Well, the main reason is that it suits their idea of how things should work. They
want to believe that all they need is a golf cart battery and a couple of fifteen watt Harbor
Freight panels and they will have free power for life. It’s true, they will believe what makes them
feel good, and the truth will not be allowed to get in the way.

SELF AGGRANDIZEMENT; This often follows on from self delusion. Our person cobbles together a system
that will light his front porch or finds a system design in a magazine that looks wonderful and
copies it. In either case there is no regard for their real needs. No understanding of system design
or their loads what-so-ever. But, all of a sudden they are the undisputed masters of solar design.
Of course they must now share their expertise with anybody and everybody. They put up a web site to
share their considerable knowledge, others look at the site and become self deluded thus starting
down the path to becoming an expert in solar power. It is not long before there are hundreds or
thousands of experts in solar power selling the same golf cart battery and and HF panel fantasy to
other people who want to believe that you can be energy independent for a couple of hundred dollars.

GREED; This is a different beast all together. Usually this type of person starts out as a second
rate automotive - marine - golf cart battery salesman who all of a sudden discovers that there is
money to be made from self deluded wannabes in the solar game. He is usually still selling the same
old batteries but now they are, of course, just as good as the worlds best, at half the price. Just
stick ten or twenty in parallel and Bob’s your uncle. The only person to win is the battery
salesman, he has your money and you have a truck load of manure.

WHAT CAN YOU DO?

Well, you can learn about solar power design. The first thing to learn is that there is no great
magical art involved, just basic math skills and a willingness to accept that solar power is free,
but the equipment required to use it is not.

Second thing to learn is that if the person giving you sage advice can not put a watt hour figure to
every load in their system, it is highly unlikely that they know enough to be giving advice.

Third thing to learn is being able to tell the difference between 1) Look what I did, pat me on the
back, aren’t I a clever little boy, web sites and 2) those that offer real advice, using real
numbers, in a clear and precise way.

Fourth thing is that people who tout that any number of parallel strings of batteries are as good as
a single series string of cells, are totally out of their depth as far as home power systems are
concerned. If there is absolutely no other option then limit the number of parallel strings of
batteries to two.

Fifth, reduce your energy use. If you can’t knock a third off your energy use, you’re just not trying.

Sixth, Don’t come to a forum such as this one and ask:

“I have an average home, how much will solar power cost”.

It only excites the wannabes and starts a barrage of nonsense. If you must ask how much, at the very
least look at your last power bill, work out what you used for a single day and post that number.
But, OTOH, the better thing would be to get copy of a spreadsheet and put your number into it. And
of course the very best would be to do a complete energy audit of everything you want to run and use
the final number in your spreadsheet. A good spreadsheet will tell you how many panels and batteries
you will need in under two minutes. Then you can get on the net and find some prices.
 
G

George Ghio

Jan 1, 1970
0
merlin-7 said:
George
It may be true that your post is correct in many ways but you leave out a
great many things.

The first one is, many people need to start small and work their way up.
This is not the most cost effective way but It does work.

Those that want to play with solar can do so. I'm talking about serious design and installation.
The way I look at it is, If someone installs a solar system (using golf
cart batteries or whatever) and they use it to run their porch light and
charge their cell phone, so be it. That's a few watts less used by burning
fossil fuels and they are learning.

Fine by me, except, after they get their porch lit they become an expert. Well, let's face it they
aren't. Not by any stretch if their imagination.
I have no idea why you think that the HF 45 watt kit is bad...lets look at
it...
You get 2 5 watt cfls, 3 15 watt panels and the mounts for them ( I do hate
the charge controller but it does make a good distribution box) for a very
good price per watt of panels, the other items are just gravy.

15 Watt panels are toys. you buy them for your children to play with and perhaps learn something
As for paralleling batteries, It can be done but requires a lot more time.
Such as, Charging each set of batteries for 1 day a month by itself and
equalizing each set when needed) but it can be done, not the best way to do
it, but It can be done.

Of course it can be done. It is now and has always been and will continue to be the second best option.
Lets look at you George...

Let me say first off that I have learned a good bit from you and am
thankful, that said. I do not understand why you always have negative
comments about people just starting out and the people tying to help them
with their first system. I think that everyone that wants to build their own
system should start out with a small set of panels, a small charge
controller and golfcart batteries or some other cheap battery. That way they
get to learn without investing a butt load of money into something they do
not understand.

Look, the plain and simple fact is that, there is just not that much to learn. Why people want solar
to be so mysterious is beyond me. Anybody can design a solar power system with nothing but the
correct formula and a calculator in around five minutes. And it will work.
George, I am here, to learn and to help others, when I can.

Well, I'm sorry. But you help perpetrate the same old myths about batteries and design that do more
harm and cost people more money than if they just learned to use the correct formula.
I do not, insult others or look down on anybody. I may make suggestions or
state a fact that I have learned from experience but I never insult.

Good, you learned that parallel batteries work, and because they work and you use them you feel free
to tell others that it is a good idea.
I made many mistakes with my system but it always preformed the way I
expected it to, correcting the mistakes just improved it.

Some how, I have managed to keep my battery bank up and running for over 2
years with a wild mix of batteries . Two optima yellow tops (sealed) and a
D-4 wet cell. Granted I only have 350 watts of panels (including 3 HF 45
watt kits) I also have to equalize the wet cell once a month or so but It
does work. It is not the best set up, but it does work.

You have built a system. This is not the same as sizing and designing a purpose built system to meet
a required load.
George, do you realize, That if everyone listened to you, no one would ever
try to start a small expandable solar system?

And a bloody good thing that would be. Small expandable systems are called toys. You are still in
the first category. You want to be right and you want to be seen as possessing knowledge. You lurch
from one poor solution to another with out benefit of an end goal.

Try this;

Do an energy audit that defines your final goal in kWh.

Get a copy of the correct formula or a spreadsheet. I will send you one if you like.

Compare the sized system to what you have now and see if what you have done so far is compatible and
able to be expanded to what you require for a price that is realistic compared to having just built
the system you need.

Something to think about.
Something to think about...

Joe



As for
George Ghio said:
June 15, 2007
The danger of solar power information, and indeed information for any other pursuit, from the web
and/or news groups is a combination of self delusion, self aggrandizement and greed.
SELF DELUSION; This is a big trap for for many people. It works like this, a person decides that he
would like to use solar power. This person has a preconceived idea of solar power based on what they
have been told by someone in a pub, seen on TV or just wishful thinking. It really doesn’t matter
where the info comes from. What matters is that it is, nine times out of ten, utter nonsense. The
problem is that the person wants to believe this information. Why do they want to believe what is
patently rubbish. Well, the main reason is that it suits their idea of how things should work. They
want to believe that all they need is a golf cart battery and a couple of fifteen watt Harbor
Freight panels and they will have free power for life. It’s true, they will believe what makes them
feel good, and the truth will not be allowed to get in the way.

SELF AGGRANDIZEMENT; This often follows on from self delusion. Our person cobbles together a system
that will light his front porch or finds a system design in a magazine that looks wonderful and
copies it. In either case there is no regard for their real needs. No understanding of system design
or their loads what-so-ever. But, all of a sudden they are the undisputed masters of solar design.
Of course they must now share their expertise with anybody and everybody. They put up a web site to
share their considerable knowledge, others look at the site and become self deluded thus starting
down the path to becoming an expert in solar power. It is not long before there are hundreds or
thousands of experts in solar power selling the same golf cart battery and and HF panel fantasy to
other people who want to believe that you can be energy independent for a couple of hundred dollars.
GREED; This is a different beast all together. Usually this type of person starts out as a second
rate automotive - marine - golf cart battery salesman who all of a sudden discovers that there is
money to be made from self deluded wannabes in the solar game. He is usually still selling the same
old batteries but now they are, of course, just as good as the worlds best, at half the price. Just
stick ten or twenty in parallel and Bob’s your uncle. The only person to win is the battery
salesman, he has your money and you have a truck load of manure.

WHAT CAN YOU DO?

Well, you can learn about solar power design. The first thing to learn is that there is no great
magical art involved, just basic math skills and a willingness to accept that solar power is free,
but the equipment required to use it is not.

Second thing to learn is that if the person giving you sage advice can not put a watt hour figure to
every load in their system, it is highly unlikely that they know enough to be giving advice.
Third thing to learn is being able to tell the difference between 1) Look what I did, pat me on the
back, aren’t I a clever little boy, web sites and 2) those that offer real advice, using real
numbers, in a clear and precise way.

Fourth thing is that people who tout that any number of parallel strings of batteries are as good as
a single series string of cells, are totally out of their depth as far as home power systems are
concerned. If there is absolutely no other option then limit the number of parallel strings of
batteries to two.

Fifth, reduce your energy use. If you can’t knock a third off your energy use, you’re just not trying.
Sixth, Don’t come to a forum such as this one and ask:

“I have an average home, how much will solar power cost”.

It only excites the wannabes and starts a barrage of nonsense. If you must ask how much, at the very
least look at your last power bill, work out what you used for a single day and post that number.
But, OTOH, the better thing would be to get copy of a spreadsheet and put your number into it. And
of course the very best would be to do a complete energy audit of
everything you want to run and use
 
We could compile an entire list of things you can do with a single 15W
solar panel but what would be the point? It won't make the newsgroup
any better.

Sure it would. I bet a lot of people have seen the HF deal on those
cheap panels and wondered about practical uses. Heck, it doesn't even
need to be truly practical since many readers are looking for the
pleasure and education of doable solar. I still get that rush even
after 13 years of living off-grid. I sometimes stand in the shade of
an array during a break from fabricating, marveling at how cool it is
to be able to do so much a dozen miles from power lines. Same thing
when we're watching a good movie at night, with the turbine controller
dumping power even with a few hundred watts total load.
It'll only place us under attack and feed the trolls.

One nitwit might complain, but obviously nobody is listening since
there's a steady stream of posters who've ignored his dopey criticisms
and gone ahead successfully with their projects. So if you have any
other ideas feel free to share them. Think of it this way - judging by
my email, some people read these groups *because* of the sturm und
drang. Your ideas might reach additional readers if they're posted in
one of those threads. ;-)

Wayne
 
G

George Ghio

Jan 1, 1970
0
Todd said:
And then he says:

What's wrong with this picture?

Nothing. It is perfectly true. Anyone can size and design a solar power system.
And the first best option is?

Single string series.
And the correct formula is?


And the better alternative is?

Single string series.
Are we back to: "Look, the plain and simple fact is that, there is
just not that much to learn. Why people want solar to be so mysterious
is beyond me. Anybody can design a solar power system with nothing but
the correct formula and a calculator in around five minutes. And it
will work." ???

There is a difference. Wayne built a system.Then kept throwing money at it until it would meet his
energy demand, at least during daylight hours.

The other option is to design to the expected load and build a system that that works to spec from
the moment it is switched on.
Of course they are. General Motors and Ford started business making
10,000 cars a day didn't they?

Not exactly the same thing but close enough, to increase production it was required that a new
assembly line be built.
And GM and Ford and George have rendered the first category obsolete.

See above.
This is the ARROGANT AVOIDER EXPERT tactic. Sell the analysis:

I'm not "selling" anything. It is all free to those who are willing to remove their head from their ass.
Final goal kWh isn't of much use if you don't know the demand pattern.
And I'll bet George's analysis does not reveal that. In fact I bet
nobody's does. I bet they just add a fudge factor to apply to the kWh
and hope for the best. And if they do that they might as well look at
the light bills and back calculate to kWh and do the same thing.

Crap. The demand pattern is a total nonsense in a well designed system. Over this 24 hour period X
kWh is consumed. If the system has the correct capacity who cares when the load is run.

Except for wayne who must needs do as much while the sun shines as he can.
You make a big deal about this formula: Is addition now called a
formula?

Well, 1+1 is a formula that yields the answer of 2.

But of course the formula for the sizing of a solar power system is a little bit more involved than
this. I can see that you may require help to understand it, but most people would be able to grasp
the basics in a few minutes.
Right ... and we've moved so much closer to the true answer to the
question haven't we?

Yes, use the correct formula to workout your required load in kWh at the beginning and use only
equipment that fits to the final solution and be prepared to dispose of a large part of this
equipment in the process of growing a system.

Far cheaper to just design and build the required system.
 
G

George Ghio

Jan 1, 1970
0
Ah, the morning comics have arrived. Thank you wayne for brightening my day.
 
G

George Ghio

Jan 1, 1970
0
philkryder said:
George -

Help me to understand a bit better.

Suppose that I minimize my load and that I then carefully size my
installation.

Let's for example say that I need 70 kwh of capacity.

Un-realistic but I'll play.
Suppose that I then obtain and install a single series string of
batteries to provide that capacity.

And, further suppose that I obtain the 8000watt of inverters needed
to meet the max instantaneous load with a reasonable "fudge factor"
for head room and motor start loads.

Suppose further that after a couple of years of successful operation
that "things change." New processes are added.
And, that I then need more capacity - suppose I need 100kwh capacity
and 10000 watts peak from my inverters.

Can I easily add additional batteries in series to reach the new
100kwh capacity?

No, and neither should you add a second string in parallel, unless you can find a set of batteries
that are of the same capacity and age(use) as the first string. Adding batteries to a series string
does not add capacity but increases voltage.
Or, must I go to a new battery size for the entire installation?

That would be the best choice. It may be that batteries of the capacity may not be available so the
second best choice would be to run two parallel strings of lesser capacity and double your battery
maint.
What is the voltage limit that I can practically install in a single
series string?

The usual for home power would be 48V. I did meet a guy who had a 240volt system. Funny thing, he
had a bunch of batteries in his trailer at the time. He wouldn't say what he was doing with his
batteries but did mention that the ones in the trailer were to replace the ones that exploded in use.
Is there a practical limit to the input voltage to the inverters? If
so, what is it?

No, you can have an inverter custom built to suit. Most people would use 12 - 24 - 48 volts. The
rule of thumb is 12V for 1000Whrs 24V for 2000Whrs and 48V for 3000Whrs +. In reality these loads
will have a fair amount of gray area in actual use.
What do I do when my capacity needs cause the single string to exceed
the input voltage specs of the inverters?

See above. That said, it would not happen. You can add all the batteries you want to what ever
voltage but, you can only add capacity by using batteries with higher capacity. Changing the
capacity of a single string of series batteries will not change the voltage and adding batteries to
a single string will change the voltage but not add to the capacity.
Must all the batteries have similar cell capacity?

No, they should be the "same" capacity to insure equal charging. That said I do know of a system, 23
- 840Ah and 1 - 1000Ah that still works but the 1000Ah is always undercharged. The owner is saving
for a new set of batteries. In a discussion such as this it would be wise to learn the difference
between cells and batteries.
Or can I add some batteries with a smaller (or larger) capacity per
cell?

Of course you can. I would suggest that you start a Christmas club account at the bank for the new
battery bank the same day you add your rogue cells.
Thanks for your thoughts and experience.

Phil

These are straight forward answers to your hypothetical question. Your question is a nonsense as far
as home power goes. As an industrial system, series - parallel batteries would be used. The charging
system would most likely cost more than the batteries and the batteries would be replaced as often
as every five years irregardless of their condition. It would all be written off on the taxes anyway.

Reality says;

70kWh/day

5 days autonomy

Battery capacity 12000Ah

Daily dod 13.5%

296 - 175W panels - 4 in series - 74 parallel strings.
 
George means well....

When he first arrived in the group I thought he was a well-meaning
boob. I even emailed another poster asking him not to mock George
quite so much. But after watching him repeatedly write wild
exaggerations and outright lies about knowledgeable posters who'd
corrected his frequent and blatant errors, I came to the conclusion
that he'd washed out of his little solar biz for very good reason. The
course he took couldn't make up for the lack of experience and
critical thinking, which is why even after 20 years he's still limited
to answering the most basic questions and posting the same elementary
stuff over and over - info that one can read on any web site without
it being contaminated with goofy criticisms.
He just has a problem with people just starting out in solar.

He has a problem with *everyone* who refuses to sign on to his tunnel
vision opinions. Doesn't matter if you're trying to charge some AAAs
or if you're one of the biggest solar outfits in the US. If you
correct George you'll get Ghioed until you shut up, which is as close
as he comes to accomplishment.
The way I look at it is.... get a hF 45 watt kit an optima deep cycle
(yellow top) a 4 amp charge controller and a small inverter.
If you do that...you will learn really quick as to what is involved in
larger solar systems without expending a lot of cash.
I ran my 2 meter ham radio and a 5 watt cfl on the above system for 6
months befor I expanded the system. It worked great.
You will learn more by hands on than by anybody telling you what you should
do...
My 2 cents

I think that's true more often than not. For example, I've talked to a
couple of guys in the last year who pretty much refuse to do any math
no matter how much I encourage them. They both insist that their
personal experience will trump any planning, and they're mostly right.
They both have 48V Outback inverters and MX60s. So their systems are
easily expanded except for batteries which worse case can be sold and
replaced.

I've done it both ways - I did a lot of measuring and estimating
before moving off-grid or spending any money. But on the wind side I
bought a small turbine to try before investing in a tower. Right now I
have a new project in the works (for a friend) - a 24' tall,
free-standing tower than can hoist a ton and be packed in to remote
locations. There are several ways it could be done, but I think I'm
going to spend a day doing the initial work on the most instinctive
approach and then seen if I like it. I'm pretty sure the days labor
will get me farther along than trying to think of the all the pros and
cons of every alternative.

Wayne
 
C

clare at snyder.on.ca

Jan 1, 1970
0
Wrong. Adding batteries, whether in series or in parallel, adds
capacity. Adding in series adds power capacity and voltage capacity.
Adding in parallel adds power capacity and current capacity. Buck and
boost DC-DC converters do the trading off of voltage for current and
vice versa and consume a little power for themselves in the process.


Just what is the nature of this maintenance? I don't dispute that
adding batteries adds to maintenance. I'm just wondering how the
maintenance differs when adding in series or in parallel?

I also have a question regarding the batteries in series. I've done
some experimenting with 3 and 4 of my 12V batteries in series being
charged directly from my auto alternator putting out say 38V across
the 3 or 50V across the 4. The batteries are all identical and about
the same age. They are not all necessarily at the same potential to
start. I found 1 of the batteries would quickly get up to 15V before
the others and so I would have to throttle back letting the others
(say at only 12.5 to 13.5) catch up. What kind of control systems are
available to detect this condition and control it?

If the batteries are identical and charged and discharged in series,
this will never happen. A "battery" is a number of cells in series.
Putting 2 12 volt (6 cell) "batteries" in series makes one 12 cell 24
volt battery. The cells will equalize on the first charge, and should
then stay equalized as they discharge and charge together.
Putting two 12 volt batteries in parallel makes 2 batteries.
 
G

George Ghio

Jan 1, 1970
0
philkryder said:
Why do you say it is unrealistic?

I don't need 5 days autonomy, but rather only 2.

35kwh per day.

That is not quite what you said. What you said was;

"Let's for example say that I need 70 kwh of capacity."

Lack of useful information. Failure to us correct and complete information results in incorrect
sizing. If you want better results you will need better input information.
It sounds like if I need to "expand later," that I would need to
remove the existing setup and re-install.
Did you imply that or did I mis-understand?

You failed to provide full and correct information. The answer is that you would need to replace
your battery bank (best solution) or double your battery bank with a parallel string of batteries of
the same capacity and age (second best solution).

The first solution would cost you less than the second because you would sell the first set of
batteries and offset the cost of the new set.

Please note that I have spent years trying to get people to realize the importance of using full and
correct figures in design of solar power systems. You preferred to listen to those who tell you what
you want to hear. Place yourself in category one. Being told what you want to hear makes you feel
good, listening to what is correct will make you feel better in the future.
 
G

George Ghio

Jan 1, 1970
0
Todd said:
Wrong. Adding batteries, whether in series or in parallel, adds
capacity. Adding in series adds power capacity and voltage capacity.
Adding in parallel adds power capacity and current capacity. Buck and
boost DC-DC converters do the trading off of voltage for current and
vice versa and consume a little power for themselves in the process.

six 12V - 100Ah batteries in series will be 100Ah at 12V

twelve 12V - 100Ah batteries in series will be 100Ah at 24V
Just what is the nature of this maintenance? I don't dispute that
adding batteries adds to maintenance. I'm just wondering how the
maintenance differs when adding in series or in parallel?

More care is required to maintain correct charge in parallel sets of batteries
It is a geometric progression

2 Parallel strings - twice the maint.

3 parallel strings _ four times the maint.
I also have a question regarding the batteries in series. I've done
some experimenting with 3 and 4 of my 12V batteries in series being
charged directly from my auto alternator putting out say 38V across
the 3 or 50V across the 4. The batteries are all identical and about
the same age. They are not all necessarily at the same potential to
start. I found 1 of the batteries would quickly get up to 15V before
the others and so I would have to throttle back letting the others
(say at only 12.5 to 13.5) catch up. What kind of control systems are
available to detect this condition and control it?

Several hours later they should all read the same (well as near as) if they don't then you have a
problem. Look at your connections to start with.

Many charge controllers have come and gone. The best charge controller is between your ears.
Unfortunately the user manual was lost in the mail.
So, what was he using as a 240+ volt source for charging? What was he
using for inverting that could take a 240V source?

If you remember, eh did not say what he was doing with his batteries.
And you think that's practical?

It would depend on the application.
What is the principle behind that rule of thumb? It seems to me a
better rule of thumb is to go as high in voltage as your charger and
inverter can support because the connecting wires are smaller and thus
the losses are lower. The downside is what you have to do to keep all
the cells in the system equalized.

Cost and efficiency. What you want and what's true are not the same thing.
I saw the above. And it would happen. You even state that getting a
custom built inverter is practical. Do you then have that custom built
inverter rebuilt? Of course not!

If it was cost effective for the job then it is practical.
Again ... absolute nonsense. If I have a 1 12V battery, 70AH string I
have 840Wh. If I have a 2 12V battery string, each with 70AH capacity,
I have 1.68kWh. I have doubled my capacity. I have doubled my voltage
if I put them in series. I have doubled my current if I put them in
parallel.

No you still have only 70Ah capacity.
It would also be important to bring into the discussion the issues of
equalizing battery cells when the batteries are in series vs when they
are in parallel!!!

Equalizing batteries is part and parcel with owning and using them, A good reg will do the job on a
regular basis.
 
G

George Ghio

Jan 1, 1970
0
Ah, here it is a nice bright Sunday morning and the comics are delivered right on time, and in full
colour. Keep up the good work, I love a good laugh.
 
G

George Ghio

Jan 1, 1970
0
philkryder said:
One of the reasons for being reluctant to make precise measurements
and calculations is that "thing happen."

As someone said, "prediction is terribly difficult, ESPECIALLY about
the FUTURE."

I want to have a system that is easily expandable, because operations
can change.

You can have an expandable system, just leave out the word "easily"
With a grid-tie system, one can let the grid carry extra load for "a
while".

Of course.
With a generator system, FUEL costs dominate the long term costs
rather than CAPITAL costs. Therefore the system is easily scaled by
buying a new generator.

Fuel will continue to rise in price. The sun will be the same price tomorrow as it was yesterday.
But consider what I must do with the series batteries that George
recommends.

I must "sell them all and get new ones all of which are the SAME
size."

Yes, and it is cheaper because you get back money for you old batteries, and make no mistake there
is a growing list of people who will pay good money for good second hand batteries.

Is it any wonder that folks are reluctant to jump in with both feet?
Is it any wonder that folks want to start small?

Look, if you want to start small, feel free. But if you don't know what you are building towards you
will probably never arrive.
The problem is not the "error bars" on measurement or calculation.
The problem is the error bars on predicting the FUTURE.

I predict that energy from sunlight will cost the same for the next several thousand years.
The equipment needed to use that energy will come down in the same period.
And the massive size of each individual step in larger systems.

Ah, now it comes down to the real bugbear, fear of the unknown.
 
G

George Ghio

Jan 1, 1970
0
Todd said:
You miss my point. Your first three comments are booga booga ....
don't try this yourself at home boys and girls.

You miss the point. Anybody can do it. And at home. And get it right. And save money in the long run.
You last comment is "this is all really trivial". So why the first
three comments?

The first comment is not to let your wishes get in the way of the truth

The second comment is to not let it go to your head when your head is in fact empty

The third comment is to beware of smooth talking salesmen who only want your money and will stroke
your ego to get it.

In short the whole point is that there is no great, dark magic about design of solar power systems.
Just true and correct numbers and a simple formula.
I have 10 12V batteries. Is single string series for this 120VDC? If
so, where do I find an inverter that takes 120VDC? If not, what is
"single string series"?

10 X 12V is 120V.

Ask an inverter manufacture that specializes in large grid tied systems.
So this is just a spitting match between you and Wayne?


You can write a spec and design and build to it perfectly ... and it
can fail because the spec was wrong. That's why even the most
knowledgeable engineers build pilot plants first.

IF the spec is wrong. Then you got it wrong and need to learn your limits before you try again.

The first system I built for myself did not work properly. The fault was entirely my lack of
knowledge. This was more than twenty years ago, there was no one to guide me and I believed what
made me feel good rather than the facts.
You miss the point again. Even if the auto manufactures had demand of
10,000 cars a day before opening their first plant, they couldn't have
opened a 10K car plant. They didn't have the knowledge. They couldn't
take the risk. In any endeavor, especially new ones, you walk before
you run.

Yes, you walk through your house doing an energy audit, you walk through the correct formula, you
walk through selecting the correct equipment, walk through the installation and turn the system on

setting the parameters for the charge controller and inverter. Put your feet up and relax.
You see above!


You sure come off as if you're selling something ... if nothing more
than you are an expert and others should just behave and listen.

You could say that I'm selling something. The price is $0.00

The product is your solar power system sizing and design. In short Knowledge that allows you to do it.
Oh really? Try this: You are sawing wood remotely from 10:00AM to
2:00PM on sunny days only. You consume 5kWh on days you use the
system. What does the design look like?

It looks just like the system I use, only larger. I cut wood maybe one day a week, the system runs
continuously day to day. If I am not there for a day, well, what does it matter.
Then try this: You are home only in the evening hours when there is no
PV output. You have a small modeling shop and run shop tools 6 hours
each evening. You also have normal micro wave, lighting, and home
entertainment demands. You consume 5kWh per day on average. What does
the design look like?

Exactly the same.
They're different aren't they?
No

Right ... everyone has the same demand pattern except Wayne.

Yeah, pretty much.
Right. But people not trying to impress with the complexity of their
knowledge base refer to that as addition rather than a formula.

It is still a formula.
And how is it you can see that? So far, every illustration you have
given is simple addition?

Yeah, good isn't it, solar power is so simple it's amazing.
See above. You admit that the demand pattern is not a concern, yet it
is a trivial exercise to show you are wrong.

Is it really.
Actually, probably far more expensive. To design and build the
required system when you don't know what is required (which you have
demonstrated you don't) means you over design the system or it under
performs. An over designed system will always be more expensive than a
scalable system where you add components as you learn the requirements
through real experience. Further, learning by experience can avoid the
folly of buying an expensive PV system when a simple diesel driven
alternator charging the batteries can outperform it at a fraction of
the cost.

The fact that you believe in a scalable system is just that you want it to be true. Put yourself in
category one.
 
G

George Ghio

Jan 1, 1970
0
philkryder said:
< snip >

How did I get a large enough inverter to meet the increased demand?

Wouldn't I need to replace the inverter as well?
Well Anthony has said it quite well, so all that's left to point out is:

"Welcome to the joys of an expandable system." Rather makes the point quite nicely. It takes very
careful planning to build a system that is expandable. Far better to plan ahead with a good idea of
what you want/need.

You are looking an an industrial power supply. That is big money. If you are not making big money
from the business then it is impracticable.

Solar energy is free, the equipment to use it is not.
 
It sounds like the implication, based on your insight and experience,
is that with current technology and economics, you believe that PV is
economical for "small" installations, but not for larger.

If you've been keeping up with the posts here you may have noticed
that there are folks with 6kW and larger setups who believe they've
made a sound investment.
Is there some "sweet spot" that you have observed?
What is the Kwh size of that sweet spot?

There's really no such thing as a sweet spot, each application is
different. Yours requires that 70+ kwh be generated during a 7 day
period and stored for use during 2 of those 7 days. That's about 50%
less energy than I make with 2 kW of tracking arrays and a 1 kW
turbine (contributes about 25% of the total) in a similar climate, so
your generating capacity will be similar as well. The difference is
that you need more than double the storage. Your choices at this point
are to make a better estimate of your consumption (it might be less
than you think), or whittle down your needs (new appliances or
whatever), or change to a combination of PV and generator etc. to
lessen the cost.

Even if you stick with the simplest make-it-and-store-it strategy, the
idea that you need 52kW of PV or even half that is pure lunacy. Since
you're obviously getting hopelessly confused here by conflicting
advice, I suggest that you spend a few minutes calling an independent
professional. Explain that you want 70 kWh (before losses) per week,
and perhaps 80 kWh of storage (keeping in mind that some of your
consumption won't be going through the batteries). The professional
will need to know exactly what climate zone you're in, and if he
doesn't ask then find someone else. Good data is readily available for
Santa Maria (only about 50 miles up the coast), so if you think your
location gets about the same amount of fog, tell the guy that and in
minutes he'll recommend an array capacity for fixed and tracking.
Beyond that he can help you decide if a turbine makes sense.

Here are some places you can call

http://store.solar-electric.com/info.html (AZ)

http://www.beyondoilsolar.com/contact_us.htm (CA)


Wayne
 
G

George Ghio

Jan 1, 1970
0
philkryder said:
Thanks George

It sounds like the implication, based on your insight and experience,
is that with current technology and economics, you believe that PV is
economical for "small" installations, but not for larger.

Oh, Christ no. PV can be economical for any size system. But only the user can make the choice
according to their needs.
Is there some "sweet spot" that you have observed?
What is the Kwh size of that sweet spot?

There is always a sweet spot, but again it is subjective. The user must decide whether or not it is
worth the effort and/or cost. For you a 10Kw system may be considered too expensive for the return,
while a university could consider the cost money well spent to protect their research energy needs
or computer security.
Or am I again, misinterpreting?

Yes and no. Does running a generator allow you the cover your costs and make a profit?

What percentage of your load could be turned over to PV and still make a profit? Lets say that with
proper sizing and costing you find that a system that will run X% of your load would be profitable.

So you build a system that will run X%.

Two years later you find that rising fuel prices and falling PV costs make running Y% of your
remaining generator load profitable for PV.

You build another system to run the Y%.

So you now have X% + Y% running on PV. This means you have three discrete systems and can only lose
a percentage through any one system failure. You don't have all your eggs in one basket. And as you
still have the generator system you can cover either an X% or Y% system failure anyway.

You might end up with four or five PV systems in the end running everything and still have the
generator for backup.

A lot easier than trying to expand a system and a lot more security of production.
 
G

George Ghio

Jan 1, 1970
0
Todd said:
So far so good, George.


I asked what was the nature of the maintenance. If more care is
required, what is that care doing?

Largely checking connections and charge levels with a hydrometer.
Doing what?

See above
See above
Doing what? And why is it climbing geometrically.

It is a dirty, tedious, job. Try it some time with a large series/parallel battery bank
If that's the case, then why doesn't the voltage across each cell
remain the same when fully charged? Why do I have to go through a
monthly equilization exercise if not to coax each cell back to being
the same?

Because every battery is an individual. A good charge regulator will do the job just fine with a
single series string of batteries and well enough for two parallel strings with a proper maintenance
program.

More parallel strings and you get more variation requiring longer equalization.
If you're going to be insulting, you shouldn't be stupid at the same
time George.

Neither insulting nor stupid, everyone got a brain and no one got a manual. You either learn to use
the tool or not, as the case may be.

I monitor my system all the time and make adjustments to the reg for summer and winter.
I didn't ask what he was doing with his batteries. I asked what he was
using to charge them. I then asked what he was using to tap that
charge (i.e. to invert from DC to AC). If you're going to be glib
George, at least pay attention.

And I said he did not offer further information, at least pay attention.
Oh really? Name an application where you have a new custom inverter
built to suit as the demands change.

Oh really! Most people in the position of needing such a service will not follow the tried and true
wankery followed by those who feel that a system should be sized to the bare minimum as determined
by measuring loads at what they think they will run the load at.

George. You completely evade my question. I asked "what's the
principle behind that rule of thumb". And your answer just hangs out
in air. It neither addresses my question nor my statement. What are
you doing George?

Cost and efficiency. How many times do you have to be told something?
And if it's not, you don't. And if it never is cost effective you
don't. Name a case where it's cost effective.

Large grid feed. 240VDC in 240VAC out.
That's current capacity. But real battery capacity (or bank capacity)
is it's ability to store and deliver energy (power). And that power is
volts x current or watts. It stores charge. When that charge moves
over time it's called current. And when that move is caused by a
voltage differential it's called power. And battery capacity is both a
function of the charge it can deliver and voltage under which it
delivers it. Are you really this stupid George?

No but you seem to be.

Battery capacity is measured in Amp Hours. Sorry but that is the way it is.

If you need 1000Ah of batteries at twelve volts then you would use 500Ah of batteries at 24 volts.
Your watts stay the same, and the actual capacity in hours of use is the same.

You see, this is the reason for using a higher voltage battery bank. It's called system sizing and
determines the capacity of the battery required. It is usually worked out on days of autonomy.
But equalization is complicated with a series string. You must assure
that no cell in the string gets too much voltage while the other cells
catch up. With batteries in parallel you never have more than 6 cells
in a string. With batteries in series (say 4 12V batteries), you now
have 24 cells in the string. It's more likely that some cells can be
overvoltaged when charging batteries in series than when charging them
in parallel.

Oh yeah, real complicated. It happens every month, automatically.

It would appear that you really are stupid. Your last statement is as worthless as the rest of your
post.
 
On Jun 17, 5:57 pm, [email protected] wrote:
.....


Wayne - where did the 52kw of PV come from?

Ghio, June 16, 2007 - "296 - 175W panels - 4 in series - 74 parallel
strings" (51.8kW)

Here are some of his previous (and very typical) GIGO calculations.

Ghio, June 1, 2007 - "48 Volt system> 3500wh/day> 250Ah batteries
Total Ah demand 81.02 > Days Autonomy 2> Daily depth of discharge 33%
20 - 80W panels (1.6kW)"

Ghio, June 1, 2007 - "a bit over 2100 Ah and 128 - 80W panels"
(10.2kW)

Ghio, May 26, 2007 - "You are using 4kW hours a day" (you wrote 4kW
load for 7 hours on 3 days per week, which is an average of 12kWh per
day)

His recommendations thus far range from 1.6kW to 51.8kW. Now, even a
blind squirrel trips over a nut occasionally, so you could keep up the
current dialogue in the hope that he might eventually stumble onto the
right numbers. But how will you know if he does? Meanwhile
knowledgeable posters will be less likely to spend time helping you
when they can see that you value gibberish as highly as thoughtful
opinions.

As I said, if you're having trouble separating the outer space numbers
from the earthly ones, then you should get an opinion from a genuine
professional. Most of them will give you a preliminary estimate over
the phone for free. You might also go back and review Sylvan's
comments.

Wayne
 
G

George Ghio

Jan 1, 1970
0
Todd. Your posts show an ignorance of system design.

You are correct. There are 1/2 as many connections in series as in
parallel. Testing charge levels by hydrometer is problematic with
sealed batteries.


I can see twice. I can't see the geometric progress. Please elaborate.

If you can't see it now, than you will never see it.
How large is a large bank?

Six parallel strings of six 2V 500Ah cells.
Oh really? What is it about a good charge regulator that will do this?
How can it do it when it doesn't know charge (voltage) across
individual batteries in the series ... it only knows the voltage
across the whole string.

Well, I, as do most people who use a correctly designed system, have only one battery.
If I have a 4 battery string, what should my voltage be across it to
achieve equilization?

Well, to start with, if you have 4 batteries you you have designed incorrectly. Also you fail to
provide correct information. What are the batteries?
How will I know no battery in the string will exceed 15.2V when
equilization is in progress on that string?

Again, lack of correct information. What are your batteries?
More variation of what?

The test was done using a bank of 2V cells. Six parallel strings of six batteries in series.

The test was preformed at the Royal Melbourne Institute of Technology.

All the cells and strings were monitored during charging and discharging. It was found that parallel
strings did not all charge/discharge at the same time, but rather that a string would charge for a
time then another string would charge then another and another and another. In the end the strings
may or may not be fully charged or even be close to the same state of charge. It was also found that
there were large current flows between strings. In some cases large enough to exceed the cabling specs.

This is not my fault. It is just the way that parallel strings of batteries work. It also explains
why maint of parallel strings is a geometric progression.

You may of course do as you wish.
That not withstanding, so far you've been both insulting and stupid in
your dialog.

The funny thing is, that if you post a generalized insult about ability, There is always someone who
will put up their hand and say "Hey, that's me. Hang on, you can't talk about me like that."

There by they condemn themselves.
What is the nature of you monitor? Do you know the voltage across each
battery at all times?

Yes I know the voltage across my battery.
What adjustments do you make to the reg in summer and winter ... and
why?

Colder batteries will take a harder charge
You brought it up as support of a strategy of ever increasing length
of series strings as opposed to shorter series strings in parallel. If
that example goes nowhere, why did you bring it up?

It happened. Unlike some of you drivel.
So what factor of safety are you recommending?

None. It is the choice of the designer and is relevant to the needs and use of the system.
Please point me to someone who can build me one of these customer
inverters.

Also, if you could point me to someone who can make me a customer buck
DC-DC converter I have need for that too.
Google

Once. But less than once doesn't help at all. Cost and efficiency are
not principles. A principle is something like "higher voltage systems
require smaller wire to deliver the same power".

Cost and efficiency is what drives the choices most people make about everything.
Please point me to such a system and its cost.
Google

Your reply is not convincing.

Believe what you like or make you feel good, it won't make any difference to the truth.
Correct, for a single battery. But a battery bank, whether connected
in series or parallel or a combination of each has a capacity that is
a direct function of the number of batteries.

Ah, A battery bank is just a battery by definition.
There's where you're going wrong George. Needs are measured in Ah.
They measured in KwH. Such a measurement takes both amperage and
voltage into consideration.

Would you like to try that again.

System capacity is measured in kWh.

Battery capacity is measured in Ah

They are not the same thing. The batteries are a component, the system is the whole.
Baloney. The reason for using a higher voltage battery bank is to use
smaller wire size.

What an ignorant little twat. And yes that is an insult.

That's why transmission lines carry hundred of
kilovolts rather than 220V. It has nothing to do with system sizing.

Choosing the correct wire size is an important part of system sizing.
The number of batteries, whether in series or in parallel has
everything to do with system sizing (as does the kWh delivery capacity
of each battery).

Amp hour capacity of each battery
The only reason you can talk about Ah ratings is you
are assuming a specific voltage (usually 12V but often 6). The true
capacity of the system is unknown until you specify both the Ah and
the voltage of the component batteries.

Not at all. The true capacity of the system is known when you have completed your energy audit.

The connection of those
batteries is irrelevant (unless you try to do something stupid like
connect a string of 4 in parallel with a string of 3).

Again you are wrong. Series connections are the first choice, parallel or series/parallel are only
the second choice.
Ok. I ask again. What voltage do you use across a string to achieve
equaliization?
17V

How do you assure that no battery in the string has a voltage across
it of more than 15.2V (for 12 V batteries)?

I don't.
How do you know when all batteries are at 15.2V so you can start the
equalization timer? (the rule on mine is 2 hours cumulative time at
15.2V)

My regulator does it.
Now George! This is an example of a worthless statement:
"Oh yeah, real complicated. It happens every month, automatically."

It is a true statement.
My equalization happens automatically every month too and I proceeded
to explain what "it" means in "it happens". You have not. If my
statement is worthless, yours isn't even on the radar.

It is quite clear that my regulator does the job once a month. Despite your out of context quote.
Give me some detail of just what happens automatically every month
George. A good answer would tell me the number of volts in your
string; the voltage you put across your string to achieve
equalization; how long you maintain that voltage to achieve
equalization; how you assure that no battery in your string exceeds
15.2V; how you know when all batteries in your string are at 15.2V and
thus equalizing; how you detect that one of the batteries has fallen
below equalization voltage (as when the bank comes under load) and
thus your cumulative timer should be turned off until all batteries
are back to 15.2V.

12V string of 2V 840Ah cells.
Every month my reg runs the voltage to 17V
I am not restricted to your 15.2V
Equalization take place during the day.
No large loads at the time.
If you evade this question again George I just consider your
participation in this dialog disingenuous and am happy to end it right
there as a total waste of time. So far your contribution has been less
than minimal.

But far greater than your ability to understand and much more correct than your misinformation.
Ya all have a nice day now.
 
G

George Ghio

Jan 1, 1970
0
beemerwacker said:
Come on George. You started your typical crap by telling everyone that
if you buy a 45 watt kit that, what was the term? "the truth will not
be allowed to get in the way." and now it's "any size system". Keep
the story straight. You're much more entertaining when you stick to
your original plot without meandering.

Sorry, but both statements are the truth. A toy system can be cost effective as a toy and a real
well designed system can be cost effective for the purpose it is built.

Grow up. The relevant part of the quote that you misrepresent is;
They want to believe that all they need is a golf cart battery and a couple
of fifteen watt Harbor Freight panels and they will have free power for life. It's true, they
will believe what makes them feel good, and the truth will not be allowed to get in the way."

The quote is about believing what makes a person feel good as opposed to accepting the truth. People
who only believe what makes them feel good are self delusional.
 
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