Newbie question
China Clipper
Here's the scenario.... 4 220 amp hour 6 volt batteries. Set 'em up in
parallel and series, total of 440 amp hours available, at 12 volts. At 120
volts, 44 amp hours. OK so far? Now, I have a solar panel about 1.6 amp
output, at around 14-15 volts, give or take. Lets assume that I have about 5
hours of usable sunlight, no loss in heat, etc etc.... I should be putting
in about 8 amp hours a day into my batteries, correct? Please tell me why or
why NOT this is correct. I KNOW this isn't a lot of power here,
folks...Humor me....
Sorry if it sounds stupid!!!
CC
David Kunz
: OK: Here's the scenario.... 4 220 amp hour 6 volt batteries. Set
: 'em up in parallel and series, total of 440 amp hours available, at
: 12 volts. At 120 volts, 44 amp hours. OK so far?
Watts is constant (volts * amps), so this is correct. HOWEVER, you
should never dischare all the way to zero! If you have a good quality
battery, a discharge to 20% is the max and most recommend that you do
this infrequently (discharge to 80-50% most of the time, and to 20%
only in emergency).
: Now, I have a
: solar panel about 1.6 amp output, at around 14-15 volts, give or
: take. Lets assume that I have about 5 hours of usable sunlight, no
: loss in heat, etc etc.... I should be putting in about 8 amp hours
: a day into my batteries, correct? Please tell me why or why NOT
: this is correct. I KNOW this isn't a lot of power here,
: folks...Humor me.... Sorry if it sounds stupid!!! CC
Unless you live in the midwest, 5 hours per day is pretty optimistic.
You'll only get full output around solar noon and on cloudless days.
However, using your numbers, 1.6 * 5 = 8 amp hours. So, you are
correct (solar panels are pretty much constant current devices).
--
David Kunz
Operator error. Replace operator and strike any key to continue...
olbab
amount of solar gives you only a tiny fraction of the energy
you were hoping for.
When I win the lottery, I'm gonna do it right, if I can find
enough ROOM on the roof....
Ol' Bab
China Clipper <tdu...@radiks.net> wrote in message
news:hmX94.6067$GS5....@newsfeed.slurp.net...
> OK:
> Here's the scenario.... 4 220 amp hour 6 volt batteries.
Set 'em up in
> parallel and series, total of 440 amp hours available, at
12 volts. At 120
> volts, 44 amp hours. OK so far? Now, I have a solar panel
George Ghio
<tdu...@radiks.net> wrote:
>OK:
>Here's the scenario.... 4 220 amp hour 6 volt batteries. Set 'em up in
>parallel and series, total of 440 amp hours available, at 12 volts.
Right
At 120volts, 44 amp hours. OK so far?
No. Where do you get 44 amp hours from. The batteries still have 440 Ah
in them. I assume that the load you wish to run is such that you expect
44 hours use. DC Load = 10 amps is this correct? AC Load 1200 watts.
These figures assume no losses.
Now, I have a solar panel about 1.6 amp
>output, at around 14-15 volts, give or take. Lets assume that I have about 5
>hours of usable sunlight, no loss in heat, etc etc.... I should be putting
>in about 8 amp hours a day into my batteries, correct?
Assuming no losses this would be right
Please tell me why or why NOT this is correct. I KNOW this isn't a lot
of power here,
>folks...Humor me....
>Sorry if it sounds stupid!!!
>CC
Not as stupid as some of the things one hears. Losses are your problem.
Inverter 10 percent
Battery charging 10 Percent
Battery discharging 10 percent
Wiring 2 - 20 percent(depends on wire guage)Could be even worse I once
saw a guy wire up a house for 12 v using speaker wire. He would not be
told. In the end he declaired Solar Power to be no good and friend of
mine bought 4 panels at a bargin price and never looked back.
Have fun.
George
--
DON"T PANIC! If in doubt run in circles scream and shout.
Sylvan Butler
>In article <hmX94.6067$GS5....@newsfeed.slurp.net>, "China Clipper"
><tdu...@radiks.net> wrote:
>>OK:
>>Here's the scenario.... 4 220 amp hour 6 volt batteries. Set 'em up in
>>parallel and series, total of 440 amp hours available, at 12 volts.
>Right
>> At 120volts, 44 amp hours. OK so far?
>No. Where do you get 44 amp hours from. The batteries still have 440 Ah
Because 12v*440ah is 5280wh, and 5280wh/120v is 44ah at 120v.
>in them. I assume that the load you wish to run is such that you expect
>44 hours use.
Bad assumption, nothing to indicate that.
> DC Load = 10 amps is this correct? AC Load 1200 watts.
>These figures assume no losses.
Those figures are also totally 100% wrong. If the DC load is 10amps,
then the AC load is only 120watts. If the AC load is 1200 watts then
the DC load is 100amps. (again assuming no losses)
This is SIMPLE Watt's law stuff. I think even "China Clipper" figured
that out.
>>Now, I have a solar panel about 1.6 amp
>>output, at around 14-15 volts, give or take. Lets assume that I have about 5
>>hours of usable sunlight, no loss in heat, etc etc.... I should be putting
>>in about 8 amp hours a day into my batteries, correct?
>Assuming no losses this would be right
Correct. (George got it right!)
> Please tell me why or why NOT this is correct. I KNOW this isn't a lot
>of power here,
It is correct, except as George pointed out, losses...
>Not as stupid as some of the things one hears.
Yeah, like 10a@12v is 1200w@120v...
>Losses are your problem.
>Inverter 10 percent
At least. Usually the efficiency curves of an inverter peak (e.g.
lowest losses) at 90% to 95%. Depending on the load you are drawing it
may be much much worse than that.
>Battery charging 10 Percent
>Battery discharging 10 percent
Usually this is quoted at needing to put into the battery 110% to 125%
of what you took out. Discharging doesn't need to be called out
seperately as you cannot measure it individually like you can charging.
>Wiring 2 - 20 percent(depends on wire guage)Could be even worse I once
Yup. You should calculate wire losses so they are satisfactory to you.
Bigger wire, less loss but more expensive up front.
sdb
--
Do NOT send me unsolicited commercial e-mail (UCE)!
Watch out for munged e-mail address.
User should be sylvan and host is cyberhighway.net.
George Ghio
xsylvan...@cyberhighway.net (Sylvan Butler) wrote:
>George Ghio (gh...@netconnect.com.au) on Wed, 29 Dec 1999 15:49:39 +0100 wrote:
>>In article <hmX94.6067$GS5....@newsfeed.slurp.net>, "China Clipper"
>><tdu...@radiks.net> wrote:
>
>>>OK:
>>>Here's the scenario.... 4 220 amp hour 6 volt batteries. Set 'em up in
>>>parallel and series, total of 440 amp hours available, at 12 volts.
>
>>Right
>
>>> At 120volts, 44 amp hours. OK so far?
>
>>No. Where do you get 44 amp hours from. The batteries still have 440 Ah
>
>Because 12v*440ah is 5280wh, and 5280wh/120v is 44ah at 120v.
Except that that we are not talking about 120v batteries. The batteries
still have 440 amp hours in them. Every thing in a Solar Power System
must relate to the batteries.
>
>>in them. I assume that the load you wish to run is such that you expect
>>44 hours use.
>
>Bad assumption, nothing to indicate that.
The statment was to gain more info.
>
>> DC Load = 10 amps is this correct? AC Load 1200 watts.
>>These figures assume no losses.
>
>Those figures are also totally 100% wrong. If the DC load is 10amps,
>then the AC load is only 120watts. If the AC load is 1200 watts then
>the DC load is 100amps. (again assuming no losses)
As the batteries provide the power, all loads must reflect this.
1200w/120=10amps comeing out of your batteries. I can see now why you
lot cant seem to make Solar Power work. What ever the ac load is the
loss is from the batteries. You may not like my method but my systems
work as designed.
>
>This is SIMPLE Watt's law stuff. I think even "China Clipper" figured
>that out.
>
>>>Now, I have a solar panel about 1.6 amp
>>>output, at around 14-15 volts, give or take. Lets assume that I have about 5
>>>hours of usable sunlight, no loss in heat, etc etc.... I should be putting
>>>in about 8 amp hours a day into my batteries, correct?
>
>>Assuming no losses this would be right
>
>Correct. (George got it right!)
>
>> Please tell me why or why NOT this is correct. I KNOW this isn't a lot
>>of power here,
>
>It is correct, except as George pointed out, losses...
>
>>Not as stupid as some of the things one hears.
>
>Yeah, like 10a@12v is 1200w@120v...
Explained
>
>>Losses are your problem.
>>Inverter 10 percent
>
>At least. Usually the efficiency curves of an inverter peak (e.g.
>lowest losses) at 90% to 95%. Depending on the load you are drawing it
>may be much much worse than that.
>
>>Battery charging 10 Percent
>>Battery discharging 10 percent
>
>Usually this is quoted at needing to put into the battery 110% to 125%
>of what you took out. Discharging doesn't need to be called out
>seperately as you cannot measure it individually like you can charging.
>
>>Wiring 2 - 20 percent(depends on wire guage)Could be even worse I once
>
>Yup. You should calculate wire losses so they are satisfactory to you.
>Bigger wire, less loss but more expensive up front.
>
I would be intrested in your design for a 3.2kW system. I think you
might just be able to do it. Nick sure couldn't.
The parametres are as follows
Daily load 3200W
Min average daily temp 3 degrees
Days autonomy 5
Latitude 35degrees
Design month Jan
Wanted all relevant information. This system is up and running in
central Victoria so I all ready know the answers. Should take about
five minutes if you know the maths. But take your time I don't expect
you to have all the info you need at hand.
Go on have a go. After all you inferred that I'm a fraud.
Nick Pine
>...The batteries still have 440 amp hours in them...
So SOME batteries contain amp-hours...
>1200w/120=10amps...
No. 1200W/120 = 10 watts.
Nick
Sylvan Butler
>In article <84dr4f$m0d$1...@news.cyberhighway.net>,
>xsylvan...@cyberhighway.net (Sylvan Butler) wrote:
>As the batteries provide the power, all loads must reflect this.
>1200w/120=10amps comeing out of your batteries. I can see now why you
George, don't be an idiot. First off your units don't match up.
Second, if you are using 1200watts at 120volt, and the source is a 12v
battery bank, you will be drawing 100amps (plus inefficiency) from the
batteries. Period. End of story.
>lot cant seem to make Solar Power work. What ever the ac load is the
>loss is from the batteries. You may not like my method but my systems
>work as designed.
Totally unbelievable. If you cannot even do simple watt's law
calculations, there is NO WAY you can design a system. if they work,
it is luck. Anyone can be lucky.
>>This is SIMPLE Watt's law stuff. I think even "China Clipper" figured
>>that out.
>>>Not as stupid as some of the things one hears.
>>
>>Yeah, like 10a@12v is 1200w@120v...
>Explained
Not.
>I would be intrested in your design for a 3.2kW system. I think you
SWAG is a minimum 1kw panels, 12+ T105 battery plus a generator to
handle the exceptions. Recommend 2kw or more panels, 10+ L16 batts.
Customer discussion is needed to balance tradeoffs. Some detail below.
>The parametres are as follows
>Daily load 3200W
Probably you mean 3200watt hours? Not a 3200w peak load? What peak
load (needed to make best determination of system voltage and battery
wiring sizes)?
>Min average daily temp 3 degrees
Is that deg F or deg C?
Really bad battery efficiency if 3F and the batteries have to be
"outside." We'd need to probably double the battery bank...
>Days autonomy 5
That will be a good-sized battery bank. Shall I assume that after five
days it is OK if the battery is totally dead, or do you want to
maintain no more than the recommended max 80% DoD after five days?
3200wh/day * 5 days is 16kwh needed. 20kwh battery bank would be a
minimum to handle 20% loss. On my personal UPS system that
is met by two parallel banks of 8-T105's (440ah at 48v nominal).
However with only 3.2kwh per day, you probably don't need a 48v system.
Mine must meet very large surge draws and so the smaller current
demands at 48v are desirable to reduce wire size (I still used 4/0
battery connects to handle 200amps).
It could be done with 10 L16's (series two to 12v, then parallel those
five sets). I do not like paralleling that many sets, so I would
recommend either a 24v system or bigger (more expensive) batts.
Trouble with 24v, each set has about 8.4kwh so three sets (12
batts) is more than our minimum 20kwh but two sets doesn't give our 20%
margin. If you went with the L16HD (375ah) then two sets (8 bats)
gives 18kwh, maybe adequate margin but probably not.
More info is needed from the customer to determine the most appropriate
cost/benefit tradeoff, especially in regard to voltage as influenced by
peak load, etc.
>Latitude 35degrees
>Design month Jan
Need to know more about the location to determine climate conditions,
e.g. how much sun to expect. Assuming average 4hrs per day (at my
house we haven't seen the sun since Dec 22, and there has been no wind;
temperature has maintained 20F-25F and the frost spires on everything
are 2-3cm long...) you will need 1kw of panel just to keep up (assuming
typical 20% losses in battery charging). Recommend 1.2kw minimum but
should have more so that the batteries do not take too many days of sun
to get charged after a few cloudy days. Wire sizing for panels depends
on distance and operating voltage.
>Wanted all relevant information. This system is up and running in
>central Victoria so I all ready know the answers. Should take about
Is that Victoria B.C. or Aus or? let's see, 35deg lat...
>five minutes if you know the maths. But take your time I don't expect
>you to have all the info you need at hand.
I don't have memorized nor ready reference to the solar specifics to
properly specify the panels. I've already given this too much time.
>Go on have a go. After all you inferred that I'm a fraud.
No, merely stated that you don't know what you are talking about.
Warren Lauzon
Before you go calling people stupid, you should get your own terminology in
order....
--
----------------------------------------------------------
Electricity from the sun since 1979
http://www.windsun.com/ (info & specs)
http://www.solar-electric.com/ (online store)
----------------------------------------------------------
"Sylvan Butler" <xsylvan...@cyberhighway.net> wrote in message
George Ghio
<wla...@worldnet.att.net> wrote:
>Watt's Law????
>Before you go calling people stupid, you should get your own terminology in
>order....
Dont tell him. This is two much fun.
George
>
>--
>----------------------------------------------------------
>Electricity from the sun since 1979
>http://www.windsun.com/ (info & specs)
>http://www.solar-electric.com/ (online store)
>----------------------------------------------------------
>"Sylvan Butler" <xsylvan...@cyberhighway.net> wrote in message
>>
>> Totally unbelievable. If you cannot even do simple watt's law
>> calculations, there is NO WAY you can design a system. if they work,
>> it is luck. Anyone can be lucky.
>>
--
Sylvan Butler
>Watt's Law????
>Before you go calling people stupid, you should get your own terminology in
>order....
Yeah, you're right. I really should. Unfortunately with only 8hrs of
sleep out of the past 48 I'm not all that sharp at the moment. At
least I know the law... P=IE. And (without inefficiency) P is the
same on both sides of any sort of electricity conversion.
>"Sylvan Butler" <xsylvan...@cyberhighway.net> wrote in message
>>
>> Totally unbelievable. If you cannot even do simple watt's law
>> calculations, there is NO WAY you can design a system. if they work,
>> it is luck. Anyone can be lucky.
sdb
RHolb99180
>OK:
>Here's the scenario.... 4 220 amp hour 6 volt batteries. Set 'em up in
>parallel and series, total of 440 amp hours available, at 12 volts. At 120
>volts, 44 amp hours. OK so far? Now, I have a solar panel about 1.6 amp
>output, at around 14-15 volts, give or take. Lets assume that I have about 5
>hours of usable sunlight, no loss in heat, etc etc.... I should be putting
>in about 8 amp hours a day into my batteries, correct? Please tell me why or
>why NOT this is correct. I KNOW this isn't a lot of power here,
>folks...Humor me....
>Sorry if it sounds stupid!!!
>CC
>
>
>
>
>
>
>
That's about right---you need a lot of solar panels to keep you batteries
charged if you plan to use a lot of power. And probably a c40 charge
controller. These batteries are charged at 1/10 there 440AH rate which is 44
amps X 12 volts = 528 watts. 4-120watt or 5-100 watt panels will work. The C40
is a 40 amp controller. The 120 watt panels will go for about $600 to $700 a
piece. The controller is about $175.
George Ghio
wrote:
>In article <84dr4f$m0d$1...@news.cyberhighway.net>,
>xsylvan...@cyberhighway.net (Sylvan Butler) wrote:
>As the batteries provide the power, all loads must reflect this.
>1200w/120=10amps comeing out of your batteries. I can see now why you
George, don't be an idiot. First off your units don't match up.
Second, if you are using 1200watts at 120volt, and the source is a 12v
battery bank, you will be drawing 100amps (plus inefficiency) from the
batteries. Period. End of story.
Oh dear george has made a mistake. Tsk. Tsk. Tsk. You are of course
right. I really must be more careful with what I post. Consider my
wrist smacked.
>lot cant seem to make Solar Power work. What ever the ac load is the
>loss is from the batteries. You may not like my method but my systems
>work as designed.
Totally unbelievable. If you cannot even do simple watt's law
calculations, there is NO WAY you can design a system. if they work,
it is luck. Anyone can be lucky.
If there is a Watts Law I suspect it would involve Steam.
>>This is SIMPLE Watt's law stuff. I think even "China Clipper" figured
>>that out.
>>>Not as stupid as some of the things one hears.
>>
>>Yeah, like 10a@12v is 1200w@120v...
Said I was sorry
>Explained
Not.
>I would be intrested in your design for a 3.2kW system. I think you
SWAG is a minimum 1kw panels, 12+ T105 battery plus a generator to
handle the exceptions. Recommend 2kw or more panels, 10+ L16 batts.
Customer discussion is needed to balance tradeoffs. Some detail below.
>The parametres are as follows
>Daily load 3200W
Probably you mean 3200watt hours? Not a 3200w peak load? What peak
load (needed to make best determination of system voltage and battery
wiring sizes)?
DAILY LOAD is not likely to be PEAK LOAD
>Min average daily temp 3 degrees
Is that deg F or deg C?
You really must try to adopt a more worldly view. The US is just about
the last hold out against the Metric System.
Really bad battery efficiency if 3F and the batteries have to be
"outside." We'd need to probably double the battery bank...
Insulation and heating would be cheaper or you could use a warm wall
and an insulated battery enclouser.
>Days autonomy 5
That will be a good-sized battery bank. Shall I assume that after five
days it is OK if the battery is totally dead, or do you want to
maintain no more than the recommended max 80% DoD after five days?
The standard here is for no more than a 70% DoD for the period of days
designed for.
3200wh/day * 5 days is 16kwh needed. 20kwh battery bank would be a
minimum to handle 20% loss.
20 kwh @ 24 volts = 833.33 Ah. You might get away with this for a UPS
but it would most likely be a bit light on for a home solar power
system.
On my personal UPS system that
is met by two parallel banks of 8-T105's (440ah at 48v nominal).
However with only 3.2kwh per day, you probably don't need a 48v system.
Mine must meet very large surge draws and so the smaller current
demands at 48v are desirable to reduce wire size (I still used 4/0
battery connects to handle 200amps).
Rule of thumb - up to 1000wh 12 volt 1000-3000wh 24 volt 3000+wh 48
volt.
The trouble with a rule of thumb is every body has a different thumb.
24 volt will do the job,
It could be done with 10 L16's (series two to 12v, then parallel those
five sets). I do not like paralleling that many sets, so I would
recommend either a 24v system or bigger (more expensive) batts.
Trouble with 24v, each set has about 8.4kwh so three sets (12
batts) is more than our minimum 20kwh but two sets doesn't give our 20%
margin. If you went with the L16HD (375ah) then two sets (8 bats)
gives 18kwh, maybe adequate margin but probably not.
If I close my eyes and try to picture what you are doimg it looks like
a giant golf cart. Why not use batteries designed for power systems. BP
PVSTOR are very good at this sort of job and have a long expected life.
Sonnenschein are also very good but I am not impressed with their
price. These days I sell a lot of SunCycle batteries but I dont know if
they are sold there.
My way -1 string of 12- 2v 1100ah batteries in Series.
More info is needed from the customer to determine the most appropriate
cost/benefit tradeoff, especially in regard to voltage as influenced by
peak load, etc.
I have found that the only thing people see is the price. With this in
mind I always do two sizings the first is sized to what the client
asked for the second is for what will do the job with a change in
lifesytle.
>Latitude 35degrees
>Design month Jan
Need to know more about the location to determine climate conditions,
e.g. how much sun to expect. Assuming average 4hrs per day (at my
house we haven't seen the sun since Dec 22, and there has been no wind;
temperature has maintained 20F-25F and the frost spires on everything
are 2-3cm long...) you will need 1kw of panel just to keep up (assuming
typical 20% losses in battery charging). Recommend 1.2kw minimum but
should have more so that the batteries do not take too many days of sun
to get charged after a few cloudy days. Wire sizing for panels depends
on distance and operating voltage.
My figures show that the panels needto have an output of 164.6Ah per
day. This looks like 3936wh per day ah*volts=wh
>Wanted all relevant information. This system is up and running in
>central Victoria so I all ready know the answers. Should take about
Is that Victoria B.C. or Aus or? let's see, 35deg lat...
OZ
>five minutes if you know the maths. But take your time I don't expect
>you to have all the info you need at hand.
I don't have memorized nor ready reference to the solar specifics to
properly specify the panels. I've already given this too much time.
>Go on have a go. After all you inferred that I'm a fraud.
No, merely stated that you don't know what you are talking about.
SYSTEM SIZING SYS. VOLTS BATT. V
PHOTO VOLTAIC 24 2
240 VOLT WATT HOURS PER DAY 3200 W HOURS
INVERTER EFFICIENCY 0.9
ACCOUNT FOR INVERTER INEFFIENCY 3555 W HOURS
12 VOLT WATT HOURS PER DAY 0 W HOURS
SYSETM VOLTAGE 24 VOLTS
TOTAL Ah DEMAND PER DAY 148.14 A HOURS
BATTERY SIZING
NUMBER OF DAYS AUTONOMY 5
MAX. ALLOWABLE DEPTH OF DISCHARGE 0.7
BATTERY CAPACITY 1058. A HOURS
LOWEST 24 Hr AVERAGE TEMPERATURE 3 DEGREES
TEMPERATURE CORRECTION FACTOR 0.92
ADJ. BATTERY CAPACITY 1150 A HOURS SELECTED
BATTERY 1100Ah
SELECTED BATTERY DISCHARGE RATE 120 HOURS
Ah CAPACITY SELECTED BATTERY 1100 A HOURS
NUMBER OF BATTERIES IN PARALLEL 1
NUMBER OF BATTERIES IN SERIES 12
CAPACITY BATT. BANK 120 Hr RATE 1100 A HOURS
DAILY DEPTH OF DISCHARGE 13.4 %
SUITABILTY OF SELECTED BATTERIES YES
PHOTOVOLTAIC ARRAY SIZING
DESIGN TILT 60 DEGREES
DESIGN MONTH JAN
TOTAL ENERGY DEMAND PER DAY 1 48.14 AHOURS
BATTERY EFFICIENCY 0.9
ARRAY OUTPUT REQUIRED PER DAY 164.6 A HOURS
PEAK SUN HOURS FOR TILT/MONTH 4
SELECTED MODULE Solarex VLX 80 SELECTED
MODULE I AT 14 V NOCT 4.71 AMPS
SELECTED MODULE NOMINAL VOLTAGE 12 VOLTS
GUARANTEED CURRENT 4.2 AMPS
NUMBER OF MODULES IN SERIES 2 MODULES
OUTPUT PER MODULE 16.9 A HOURS
NUMBER OF PARALLEL STRINGS 9.7STRINGS
George
George Ghio
Pine) wrote:
>George Ghio <gh...@netconnect.com.au> wrote:
>
>>...The batteries still have 440 amp hours in them...
>
>So SOME batteries contain amp-hours...
>
>>
No Nick only potential. Sorry
George Ghio
<gh...@netconnect.com.au> wrote:
--