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What's need to start building a solar power system?

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Posted by JNJ on July 27, 2003, 3:59 pm
Although money is tight, I would like to start building a solar power
system.  It would be something I build small then gradually increase over
time.  What's needed to build such a system a little at a time?

Posted by Dan Metcalf on July 27, 2003, 5:13 pm

A simple and small solar system isn't all that difficult.

First, and foremost you'll need PV panels... It wouldn't be solar electric
without them.

Get a couple of deep cycle, golf cart type batteries.  If you are planning
on starting with a 12vdc system then you'll need 2 at a minimum.  (They are
usually 6vdc batteries)

I would recommend a charge controller oversized for your initial system so
you have room to grow.

You'll need some kind of overcurrent protection: fuses or breakers.  If your
system is really small you can go to the local automotive parts place and
get some heavy duty DC pull fuses, or you can even use SquareD QO breakers
for 12 & 24vdc systems.  (I really like the breakers myself, and they aren't
that expensive.)

Lastly you'll probably want some kind of inverter, and that can be anything
from one of those small in car plug type to a direct wire in system.
Depending on your budget and needs you'll have to look into the inverter
more.  I love my Exeltech inverter for its quality power, but at $00+ the
XP1100 might be too big for your budget.  They do have smaller models too.
Of course there are other manufacturers out there that make non-pure sine
wave inverters that are of good quality and much cheaper, but that's a whole
other discussion.

Take a gander at my website for an idea of what is entailed.

Dan Metcalf
dan at metcalfsdotcom
The Sun!  Your source of energy for 5 billion years!
  Free while supplies last!

Posted by offgridman@cs.com on July 27, 2003, 5:18 pm
 1. Decide what the completed system size will be.
2. Decide what the completed system voltage will be.
3. Choose charge controllers, wiring, breakers, fuse holders, panel
mounting location and panel mounts based on desired completed design
voltages and size. This might keep you from double buying components You
may decide to buy small components like charge controllers as a
disposable item or use it for night lighting or even resell it later.

OR, just buy a small charge controller a couple of 50 watt panels, four
golf cart batterys a small cheap inverter and start enjoying solar
energy. Once you have a small system you start learning and
understanding what solar costs and what it can do. I prefer this method.
  It is a lot more fun. I started with a C12 trace and moved up to a 120
helitrope pulse with modulated charge controller. The C12 now functions
as a outside lighting controller with a couple of 12 volt fluorscents
lighting my entrances. It is really nice arriving after dark to
illuminated walkways. The C12 has been functioning for a few years now
with no problem. I feed the lights from the main battery bank and use a
cheap solar panel on the C12 as a sun sensor. The C12 needs a panel
because when the volatge drops that is when the C12 determines it is
dark and needs to turn on the lights and start timing how long they
operate. The timer is adjustable. I really like the fact that they C12
uses the panel to determine when it is dark. This adjusts for the
changing length of the days so I never have to reset the time that the
lights come on. The always come on about 15 minutes befor sun down.

I have been adding panels as I can afford them and have ~30 amps of
charging available now in full sun. I have three inverters a 1500 watt
heart, a 600 watt portawattz, a cheap 150 watt import. All are over five
years old. I seem to use the 600 watt inverter most. I have the
inverters switchable with breakers and i can throw a couple of breakers
to choose which inverter I want to run the cabin off of. The 600 watt
can run the TV a couple of fans and a few lights with no problem. I even
use it to run my 1/2inch VS makita hammer drill on occasion.
I use the 1500 watt inverter when I have visitors mostly.
Forgive my rambling on.

JNJ wrote:

Posted by JNJ on July 28, 2003, 3:27 am
 Ok, we've entered Greek on me here but that's ok -- I'm a quick learner.  :)

One thing I'm having difficulty grasping are the various energy conversions.

I see there are 12, 24, and 48 volt systems.  Near as I can tell, it would
appear 24 volts is about average for a home so this is the direction I'm
currently looking.  This is also where I start to drop off in understanding.

I'm fortunate in that our local powerco actually tracks electrical usage
(and gas usage for that matter) over a period of roughly two years.  Based
on this I came up with a comfortable average usage of 1200kWh per month.
This is using a gas based range, hot water heater, and furnace and with
various energy conservation tactics goin' on (for example we've only run the
AC 5-7 days this year so far).  Our worst months were July and August last
year at roughly 2000kWh.

Going from here, how do I figure out what type of system would be needed to
handle our needs partially or fully?  I see that panels give measurements in
Watts and batteries are in Amps.  How do I get between the two, determine
how much average charge the panel will give, compare charge on the panel to
usage, and so forth?

Thanks in advanced for the answers....


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