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Information Technology Consortium |
September 2000 Bulletin
Inside:
Volunteer’s Handbook to Solar Energy
Maintenance 101
Volunteer’s Handbook to Solar Energy
Solar energy is new to many volunteers, so we
want to share bits and pieces of information as we
come across them.
First, lets review the parts of a solar system.
Solar Panels (photovoltaic cells) - use photons to
energize electrons. Electric current is the flow of
electrons.
Charge Controller - regulates electricity so that the
batteries don’t overcharge.
Batteries - (usually lead-acid) - store electricity for later
use. Even if a computer is running directly off the
sun, batteries are needed to buffer the electricity.
Inverter - converts the DC (12v) sine wave to AC (220v).
You can’t run a computer without an inverter.
Computers - the tool you want to run off the sun.
How much would one expect to pay for
parts in a solar array?
Small computer lab
(12 computers for 12 hours a day):
Trace C-40: 40 amp charge controller $134
Concorde Pvx-12105:
105 amp hour battery $129
Solarex SX-55U: 55 watt panel $237
XP (1100W) 12VDC to AC Inverter $710
Total cost: $10,000
(This array should last 10 years. Prices are from
www.mrsolar.com. Cost includes 30 panels
(1650W), 1 controller, 6 batteries, and 2 inverters
to provide continuous daily power during dry
season. Estimates exclude consideration of air
conditioners but allow the use of multiple electric
fans.)
This cost can be compared with using a generatbor:
Small computer lab
(12 computers for 4 hours a day):
Generator purchase: $200
Minimum monthly fuel cost:
(4 hours day for 20 days): $50
Total Cost after 10 years: $10,000
(Estimates are from the Essau DHT. Cost
includes a 9% inflation adjustment and a 2nd
generator purchase after 5 years. Fuel cost:
D6.75/liter. 5L consumed each 4 hours.)
The following is from www.mrsolar.com:
What Kind of Inverter do I need?
What kind of inverter do I need? The type and
size of inverter necessary depends on your
application. To determine this you must first
calculate your maximum load on the unit, which
is the most you will b running off of the inverter
at one time. There are basically four size ranges of
inverters. The first is 50-300 watts; these are small
portable inverters. These inverters are ideal for
AC only laptops; small lights and other minimal
draw AC loads. The next size range is 300-800
watts. These are also somewhat portable, and still
have the outlets on the front of the inverter.
The inverters mentioned are good for small
microwaves and other small appliances. We also
have inverters ranging 800-2000 watts. These units
usually have battery chargers built into
them, therefore they are usually added into your
existing AC system. They are also good for
medium size AC loads, or running multiple
smaller loads at one time. The final inverter
grouping is a permanently installed unit ranging
2000 watts and up. They function much like
small generators, yet are completely silent in
operation and are also great for your biggest
draws, such as refrigerators.
The other question that needs to be answered
when selecting an inverter is the type of wave
form. If you are running sensitive electronic
equiptment, like fax machines, laser printers or
high tech stereo equipment you need a sinewave
inverter. A sinewave inverter has a wave form
that is very similar to the form of grid electricity.
Other options may include modified sinewave,
which is fine for items that are not supersensitive
to clean power.
How do I determine how much juice I
need to power a lab?
I was getting an egg sandwich from the corner
Bitik (a compound shop that sells a few items like
rice and bread) and I noticed afterward that the
scrap paper used to wrap my sandwich was filled
with information about solar power. So I went
back and bought a lot more egg sandwiches.
Here’s what I learned:
The loads of household items:
Computer 50W
Monochrome Monitor 30W
VGA color Monitor 50-75W
Laptops 20-60W (Notebooks
take less, older portables take more)
Dot matrix printer 200W
Ink Jet Printer 30W
Laser Printer 1500W
Air Conditioner 1500-3000W
Fan 60W
Coffee maker 1000-1500W
Use this table to determine how many watts your
computer lab requires.
Devices which heat things up or
cool things down draw a great
deal of energy. This includes ACs,
OVENs, or refridgerators.
The previous example designed a solar lab that
would handle 1500W comfortably. This
corresponds to 12 computers, 12 VGA monitors,
1 Ink Jet Printer, and 4 electric fans. Lighting and
DC fans could also run off the solar panels if 5-10
additional panels were added.
Maintenance
The following are useful websites:
http://www.hardwarecentral.com - a place to get your
qustions answered in a discussion forum.
http://www.cnet.com - a large site for downloading
software.
http://www.pricewatch.com - a search engine for
finding the lowest prices on new or used
computer parts. Links you up with companies
willing to ship parts internationally.
http://venus.spaceports.com/~canada/webhq -
a place to get manuals for really old 486 and
pentium motherboards. You can also download
some great diagnostic programs.
Cost Cutting Tips for Computer Labs
If your lab has Internet access and you are in a
developing country, you are probably using the
Internet the wrong way. People in Africa are
typically charged for phone calls (including
Internet calls) on a per minute basis. So instead of
calling up and staying connected, try calling just
to send or receive prepared information.
1. Use a POP3 email system.
POP3 is a system where people write their email and then send and receive email once a day.
Eudora is a free offline email reader, and yahoo
offers free POP3 email to anyone. So all you pay
for is the 10 minute phone call each day to get
new mail and send pre-written mail.
2. Use mirrors of websites on the local network
or on a single computer.
Instead of connecting to the Internet to read a
popular website, copy the website to disk using a
web spider and then browse when you’re not
racing against time to get off the phone. Teleport
Pro is a free program that lets you copy small
websites to disk. The full version is $40, which
can copy gigabyte-sized websites.
Computer Testing Tips from
http://venus.spaceports.com/~canada/webhq
A.)GENERAL TESTING TIPS.
Before you begin, download a few of our
Diagnostic Software Tools to pinpoint possible
problem areas in your PC. Ideally,
troubleshooting is best accomplished with
duplicate parts from a used computer enabling
"test" swapping of peripheral
devices/cards/chips/cables. In general, it is best to
troubleshoot on systems that have been
leaned-out. Remove unnecessary peripherals
(soundcard, modem, harddisk, etc.) to check the
unworking device in as much isolation as
possible. Also, when swapping devices, don't
forget the power supply. Power incompetency
(watts and volts) can cause intermittent problems
at all levels, but especially with UARTS and
HD's.
Inspect the motherboard for loose
components. A loose or missing CPU, BIOS
chip, Crystal Oscillator, or Chipset chip will
cause the motherboard not to function. Also
check for loose or missing jumper caps, missing
or loose memory chips (cache and SIMM's or
DIMM's). To possibly save you hours of
frustration I'll mention this here, check the BIOS
Setup settings. 60% of the time this is the cause of
many system failures. A quick fix is to restore the
BIOS Defaults. Next, eliminate the possibility
of interference by a bad or improperly set up I/O
card by removing all cards except the video
adapter.
The system should at least power up and wait
for a drive time-out. Insert the cards back into the
system one at a time until the problem happens
again. When the system does nothing, the
problem will be with the last expansion card that
was put in.
B.)RESETTING CMOS.
Did you recently 'flash' your computers
BIOS, and needed to change a jumper to do so?
Perhaps you left the jumper in the 'flash' position
which could cause the CMOS to be erased.
If you require the CMOS Reset and don't have
the proper jumper settings try these methods:
Our Help Desk receives so many requests on
Clearing BIOS/CMOS Passwords that we've put
together a standard text outlining the various
solutions.
C.)NO POWER.
Switching power supplies (the most common
used PC's), cannot be adequately field-tested with
V/OHM meters. Remember: for most switching
power supplies to work, a FLOPPY and at
least 1 meg of memory must be present on the
motherboard. If the necessary components are
present on the motherboard and there is no
power:
1) check the power cable to the wall and
that the wall socket is working. (You'd be
surprised!)
2) swap power supply with one that is
known to work.
3) if the system still doesn't work, check
for fuses on the motherboard. If there are none,
you must replace the motherboard.
D.)PERIPHERAL WON'T WORK.
Peripherals are any devices that are connected
to the motherboard, including I/O boards,
RS232/UART devices (including mice and
modems), floppies and fixed-disks, video cards,
etc. On modern boards, many peripherals are
integrated into the motherboard, meaning, if one
peripheral fails, effectually the motherboard has
to be replaced.* On older boards, peripherals
were added via daughter boards.
*some MB CMOS's allow for disabling on-
board devices, which may be an option for not
replacing the motherboard -- though, in
practicality, some peripheral boards can cost as
much, if not more, than the motherboard. Also,
failure of on-board devices may signal a cascading
failure to other components.
1. New peripheral?
a) Check the MB BIOS
documentation/setup to ensure that the BIOS
supports the device and that the MB is correctly
configured for the device. (Note>> when in
doubt, reset CMOS to DEFAULT VALUES.
These are optimized for the most generalized
settings that avoid some of the conflicts that
result from improper 'tweaking'.)
b) Check cable attachments & orientation
(don't just look, reattach!) [Editor’s Note: This
realllly works! ]
c) If that doesn't work, double-check
jumper/PnP (including software and/or MB
BIOS set) settings on the device.
d) If that doesn't work, try another
peripheral of same brand & model that is known
to work.
e) If the swap peripheral works, the original
peripheral is most likely the problem. (You can
verify this by testing the non-working peripheral
on a test MB of the same make & BIOS.)
f) If the swapped peripheral doesn't on the
MB, verify the functionality of the first peripheral
on a test machine. If the first peripheral works on
another machine AND IF the set-up of the
motherboard BIOS is verified AND IF all
potentially conflicting peripherals have been
removed OR verified to not be in conflict, the
motherboard is suspect. (However, see #D
below.)
g) At this point, recheck MB or BIOS
documentation to see if there are known bugs
with the peripheral AND to verify any MB or
peripheral jumper settings that are necessary for
the particular peripheral to work. Also, try a
different peripheral of the same kind but a
different make to see if it works. If it does not,
swap the motherboard. (However, see #D below.)
2. Peripheral that worked before?
a) If the hood has been opened (or even if it
has not), check the orientation and/or seating of
the cables. Cables sometimes 'shake'loose or are
accidentally pulled out by end-users, who then
misalign or do not reattach them.
b) If that doesn't work, try the peripheral
in another machine of the same make & BIOS
that is known to work. If the peripheral still
doesn't work, the peripheral is most likely the
problem. (This can be verified by swapping-in a
working peripheral of the same make and model
AND that is configured the same as the one that
is not working. If it works, then the first
peripheral is the problem.)
c) If the peripheral works on another
machine, double-check other peripherals and/or
potential conflicts on the MB, including the
power supply. If none can be found, suspect the
MB.
d) At this point, recheck MB or BIOS
documentation to see if there are known bugs
with the peripheral AND to verify any jumper
settings that might be necessary for the particular
peripheral. Also, try another peripheral of the
same kind but a different make to see if it works.
If not, swap the motherboard!
E.)OTHER INDICATIONS OF A PROBLEM
MOTHERBOARD.
1. CLOCK that won't keep correct time.
>>Be sure to check/change the battery.
2. CMOS that won't hold configuration
information.
>>Again, check/change the battery.
Note about batteries and CMOS: in theory,
CMOS should retain configuration information
even if the system battery is removed or dies. In
practice, some systems rely on the battery to hold
this information. On these systems, a machine
that is not powered-up for a week or two may
report improper BIOS configuration. To check
this kind of system, change the battery, power-up
and run the system for several hours. If the
CMOS is working, the information should be
retained with the system off for more than 24
hours.
F.)BAD MOTHERBOARD OR OBSOLETE
BIOS?
1. If the motherboard cannot configure to a
particular peripheral, don't automatically assume
a bad motherboard, even if the peripheral checks
outon another machine -- especially if the other
machine has a different BIOS revision. Check
with the board manufacturer to see if a BIOS
upgrade is available. Many BIOS upgrades can be
made right on the MB with a FLASH RAM
program provided by the board maker.
See our BIOS page for more information.
Editor’s Final Note:
This shoud be a starting point for more
information. If you have a good website or
business, give it to me so I can put another
newletter together in January.
The next issue should have a price guide
for the Internet and for The Gambia. Solar
equipment (David Mills), monitor and power
supply repairs (Jackie and Hethur), and stabilizers
(Marc). Toodles.
Marc Maxson
October 15th, 2000
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Information Technology Consortium Newsletter - Volume 1 - September 2000