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Posted by Tecknoz on July 25, 2005, 12:18 pm
 

I want to set a Pv system just for one room .At first it will power  a
desktop computer,Crt monitor , Dsl Modem and a  Laptop computer with a power
supply. The desktop computer will be on almost 24 hr/7.
I want to use too a tranfers switch to select between solar and grid energy
just in case I need it.
I live in the Caribbean.

How many PV panels (watts each,dc voltage) do I need
What kind or type of inverter?
What kind of battery and how many to supply power during the nigth?


Later I want to add to the system the Tv, Satellite receiver ,VCR- DVD
System.They will be used mostly in the nigth for about 5 hours.


 Thanks



Posted by Blue Cat on July 25, 2005, 1:03 pm
 


What you want will involve some basic decisions and a lot of calculations.
Do you want to run your equipment on 12 volts dc or 120 volts ac? If you
choose the latter, you will need an inverter capable of running all your
equipment.

If you run your equipment on 120 vac, then a transfer switch is viable.
However, most desktop computers are not tolerant of even momentary power
outages. They don't harm the hardware, but cause Windows to reboot and run
Scandisk. You will need an uninterruptible power supply to cope with the
outages.

To calculate solar panel requirements, estimate the number of average hours
of sunshine your area gets in a day. Also take into account periods of
cloudy and rainy weather. Total power should be  P*(H/h), where P is total
power requirements. H is number of hours per day equipment is used, h is
average hours of sunshine per day.

Use golf cart batteries for energy storage.  This is an overview of what you
have to do.



Posted by Jim Baber on July 25, 2005, 8:08 pm
 This is a multi-part message in MIME format.
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<body bgcolor="#ffffff" text="#000000">
<big><font size="-1"><big>Jim Baber wrote:<br>
In General I completely agree with Blue Cats comments but I will append
some additional commentary in the appropriate areas.<br>
</big></font></big><br>
Blue Cat wrote:
<blockquote cite="midKp5Fe.30236$do5.14355@bignews5.bellsouth.net"
 type="cite">
  <pre wrap="">"Tecknoz" <a class="moz-txt-link-rfc2396E" href="mai=
<a class="moz-txt-link-freetext" href="news:9fe09$2e4d88b$0edc191$=
  </pre>
  <blockquote type="cite">
    <pre wrap="">I want to set a Pv system just for one room .At first =
it will power  a
desktop computer,Crt monitor , Dsl Modem and a  Laptop computer with a
power
supply. The desktop computer will be on almost 24 hr/7.
I want to use too a tranfers switch to select between solar and grid
energy
just in case I need it.
I live in the Caribbean.

How many PV panels (watts each,dc voltage) do I need
What kind or type of inverter?
What kind of battery and how many to supply power during the nigth?


Later I want to add to the system the Tv, Satellite receiver ,VCR- DVD
System.They will be used mostly in the nigth for about 5 hours.


Thanks

    </pre>
  </blockquote>
  <pre wrap=""><!---->What you want will involve some basic decisions a=
nd a lot of calculations.
Do you want to run your equipment on 12 volts dc or 120 volts ac? ....</p=
re>
</blockquote>
<font face="Helvetica, Arial, sans-serif"><big>Jim's two bits:
Generally speaking, I have noticed that buying 12 VDC powered equipment
like "Tecknoz" desires is more expensive and not always possible. If
it is, and will be locally supported, it will require less solar PV
wattage, and therefore may be the best way to go financially. However </b=
ig></font><font
 face="Helvetica, Arial, sans-serif"><big>"Tecknoz" </big></font><font
 face="Helvetica, Arial, sans-serif"><big>will have a much more limited=

choice in equipment, and may still have to add 120 VAC in the future.</bi=
g></font><br>
<blockquote cite="midKp5Fe.30236$do5.14355@bignews5.bellsouth.net"
 type="cite">
  <pre><>.............  If you
choose the latter, you will need an inverter capable of running all your =

equipment. If you run your equipment on 120 vac, then a transfer switch i=
s viable.
However, most desktop computers are not tolerant of even momentary power =

outages. ..............</></pre>
</blockquote>
<pre><big><font face="Helvetica, Arial, sans-serif">Jim adds: There are good grid tie inverters available that include this transfer switch func=
tion,
which will eliminate this momentary loss of power problem.</font></big></=
pre>
<blockquote cite="midKp5Fe.30236$do5.14355@bignews5.bellsouth.net"
 type="cite">
  <pre wrap="">.... They don't harm the hardware, but cause Windows to =
reboot and run
Scandisk. You will need an uninterruptible power supply to cope with the =

outages.
  </pre>
</blockquote>

<big><font face="Helvetica, Arial, sans-serif">Jim concurs, but
emphasizes that a good UPS (</font></big>uninterruptible power supply) <b=
ig><font
 face="Helvetica, Arial, sans-serif">is very desirable for <u><i><b>any=
</b></i></u>
desktop computer. If you look at the APC web site they have a tool to
help you determine what size of a UPS you need. I have not had a
computer crash in the last 4 years. I had averaged 3 or 4 a month
before I put an APC "Back UPS Pro 1100" UPS on my system. It cured
some very dirty power problems. </font></big><br>
<blockquote cite="midKp5Fe.30236$do5.14355@bignews5.bellsouth.net"
 type="cite">
  <pre wrap="">To calculate solar panel requirements, estimate the numb=
er of average hours
of sunshine your area gets in a day. Also take into account periods of
cloudy and rainy weather. Total power should be  P*(H/h), where P is tota=
l
power requirements. H is number of hours per day equipment is used, h is =

average hours of sunshine per day.

Use golf cart batteries for energy storage.  This is an overview of what =
you
have to do. </pre>
</blockquote>
<big><font face="Helvetica, Arial, sans-serif">Jim: You can use cart
batteries, they aren't </font></big><big><font
 face="Helvetica, Arial, sans-serif">quite </font></big><big><font
 face="Helvetica, Arial, sans-serif">as good as the deep charge cells
made for PV, but are readily obtainable. Also, I suggest you use the
SMA Sunny Island inverter because you can also hook it up to the grid,
solar cells, batteries, and a wind or motor generator at the same time.
It is not real large, it is just about 15 Amps at 120 VAC as I recall,
but it does contain a transfer switch function also. I think you
should consider a small wind generator, as it will function after dark,
which will often help a lot to maintain a charge on your batteries. If=

you should use a small motor generator with the Sunny Island, it would
along with the batteries also provide a very good emergency power
supply in a hurricane situation.<br>
</font></big>
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Posted by Mel on July 25, 2005, 2:39 pm
 Step 1: reduce your energy needs - (ie replace your crt monitor with a
flat screen, make sure your desktop pc is efficient, eventually replace
it with a laptop - these will make your overall goal cheaper to achieve)

Step 2 : calculate how much power (instantaneous) and energy  (over
time) you need and at what voltage (12/24/48vdc, 120/230/240vac)buy
looking at teh power & consumption information in the equipement
documentation, or by measuring with an energy meter.

- this will be used to size your system (panels & batteries) and decide
what type of inverter

Step 3 : read a bit about sizing and pv in general
try: (from a previous thread:

wmbjk a crit :
 > On Mon, 18 Jul 2005 14:16:46 GMT, Michelle P
snip
 > This book is well recommended http://www.solarsolar.com/solarbk.html
 > > As little as $2 here>
(Amazon.com product link shortened)
388-4335804
 >
 > > And there's lots of free info on the web
 > > http://www.rebelwolf.com/essn.html  online magazine
 > > http://www.green-trust.org   a very comprehensive renewable energy si=
te
 > > http://offgrid.homestead.com/OffGridersPage.html  Several off-grid
 > homes. Lots of different locations and approaches
 > > http://www.autobahn.mb.ca/~het/energy/pv_faq.html   Answers to
 > frequently asked questions about solar
 > > http://www.homepower.com/education/index.cfm  Home Power magazine
 > education section
 > > http://www.homepower.com/magazine/downloads.cfm  Home Power magazine =

free download section
 > > http://tinyurl.com/dvlha  Home Power magazine CDs
 > > http://www.nrel.gov/homer/   System sizing software
 > > http://www.solar-electric.com/   Comprehensive web site of solar
power equipment and advice
 >
 > Wayne
 >


Step 4 : get in contact with an installer, you'll know what to ask for
and s/he (should) know what's best for you (not necessarily much more
expensive than a do it yourself approache if you havn't got the competenc=
es)

Or you can try installing everything yourself, you need a minimum
"handyman" level and quite a bit of time spent reading up on sizing,
installation, codes and standards etc to make sure your system is safe
and reliable + some equipement for the installations itself


Mel



Tecknoz a crit :


Posted by Bud Weather on July 25, 2005, 11:34 pm
 Greetings,

I agree with the comments posted previously about the crt monitor being
inefficent and being desirable to replace. The desktop computer iteself
from my experiance should not be a problem in and of itself as they
rarely take the peak amparage that the power supply is designed for.


Here's a breakdown of power use for ya. The actual power consumption of
your household appliances may vary significantly from these figures:

Computer    200 Watts  24 hours    15.7 A/H@12v    376.8 AH/day
HUGE LCD Monitor 50 Watts  24 hours    3.9  A/H@12v    93.6  AH/day
Modem        15 Watts   24 Hours    1.1  A/H@12v    26.4  AH/day
Laptop        25 Watts   24 Hours    2    A/H@12v    48    AH/day
TV 19" color    70 Watts    5 Hours    1.6  A/H@12v    8     AH/day
Satellite Reciever 60 Watt  5 Hours    4.7  A/H@12v    23.5  AH/day
DVD-VCR combo    40 Watts    5 Hours    3.1  A/H@12v    15.5  AH/day

So...    that gives us a total of about 592 amp hours at 12 volts
You only want to bring your batteries down to 50% full, more than that
drastically reduces the life of your batteries. Many are designed to be
brought down to only 20% full but I'd never recommend you do that to them.

I generally design systems to have 3 days of storage as it's not unheard
of to have 3 days of clouds.

592 amps X 2 (50% discharge) x 3 (days) = 3552 Amp hours (the size of
your bank)

Trojan's L16P is the defacto standard solar battery at 6 volts and 390
amps, it requires pairs for 12 volt, therefore 9 pair should be enough.
They list in my store at $10USD each. $780 for the bank, if you buy
that many from someone they should give you a deal.
That is quite a big bank though, you may want to check out something
more compact like the GNB Absolyte IIp's I have a set of em at home and
I love em.

Inverter-wise I would recommend a Xantrex (formerly trace) DR1512. It's
a 1500 Watt inverter, an automatic transfer switch, and a built-in 70
amp battery charger. They retail for about $50USD.

Just a guess at your hours of sunlight a day is 6, I'm using that number
to calculate your panels. 598 AH divided by 6 hours is about 99
Amps/hour needed to keep up with you.

I sell Kyocera solar panels because they aren't (yet) owned by an oil
company. Also they are all the same width regardless of wattage, makes
em easy to mount. A KC120 (120 watt panel) puts out 7.1 amps/hour. So
you need 14 of em. They cost $20USD each, $680 total.

Charge control. 99 amps is absurd to try to control so I recommend
wiring the panels for 24volt and using a Blue Sky Solar Boost 6024h.
They retail for $18USD. The 6024h can charge your 12v battery bank off
of your 24 volt array and can handle up to 60 amps at 24 volt. Running
your array 24 volt also reduces the wire size you'll need as it
decreases the amperage.
(Volts X Amps = Watts)

Since your power needs are consistant and large, I recommend you get a
Honda EU2000 Generator for backup power. I sell them for $050USD.

So here's an incomplete breakdown:

18 Trojan L16p Batteries          $780
1  Xantrex DR1512 inverter/charger    $50
14 KC120 solar panels            $680
1  Blue Sky 6024h            $18
1  Honda EU2000i Generator        $050

Incomplete total:  $4,878

Additional things to think about:

-Lightning arrestors (ac and dc side)  $0 ea

-Solar Panel Racks  price varies

-Panel Wiring       size varies with distance, price varies with size

-Fuses on the PV line, on the battery line from the charge control, from
the batteries to the inverter and a circuit breaker power panel (like a
normal house) after the inverter and before your equiptment.

-Battery wiring   can vary

-Power meter    a TM500 for $25 would show you how much power yer using,
have left, etc...   A good thing to have.

I hope this helps, if you need more info on any of these products check
out my website  http://www.thesolarshop.net/  or e-mail the shop at
solarshop@thesolarshop.net


Regards,

Bud Weather
Solar Shop Weblackey
Tonasket, Washington USA
http://generalspecifics.afraid.org/


Tecknoz wrote:


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