MaximumPC 2008 09

spectrum: Infrared light possesses very
little energy but ultraviolet light contains a
great deal of it.
Most modern photovoltaic cells are capa-
ble of converting only high-energy photons
into electrical current, which explains why
mainstream solar panels are so ineffi cient.
One of the most promising ideas for increas-
ing the effi ciency of solar energy is to stack
cells with diff erent properties on top of one
another. This way, high-energy photons can
be captured by a cell on the top of the stack,
while lower-energy photons pass through
to subsequent cells that are better suited to
those photons’ wavelengths.

AC/DC
The electrical devices in your home (appli-
ances, computers, air conditioners, lights,
and so on) operate on alternating current
(AC), but a solar array produces direct
current (DC). The solution is to install an
inverter that converts the solar array’s DC
into AC. Inverters are designed to power
off when there isn’t enough electrical cur-
rent for them to operate, e.g., at night.
Solar panels produce the most power in
the presence of direct sunlight, but they’ll
produce some energy on cloudy or even
rainy days. They can’t produce any juice
at night, of course, so you’ll need some
means of storing the electricity that they
create when the sun is shining. Batteries
can provide total independence from your
local electric company, enabling you to po-
tentially live “off the grid,” but this solution
presents a host of environmental problems,
and there’s no guarantee it will provide all
the energy you’ll need. The more practical
alternative is to tie your system into the
electrical grid.
In a grid-tied system, you sell the
excess energy your solar array generates
to your local utility, and you buy back the
electrical power you need for your home.
With this method, the utility acts like an
unlimited energy-storage system, giving
you all the power you need whenever you
need it. The inverter is connected to the
meter the electric utility uses to measure
your consumption, which means your
meter will spin backward whenever you
generate more than you consume.
For most households, the reward for
going solar is more feel-good than finan-
cial: It could take a decade or longer to
recoup the investment in even a moderate-
size system. That situation is changing
rapidly as the escalating cost of produc-
ing electricity from fossil fuels moves in
inverse proportion to the cost of deriving
energy from the sun.

AUTOPSY

Zalman ZM-M220W

Zalman’s monitor pushes the limits of stereoscopic technology by

packing three dimensions into a single LCD panel. Here’s how it works!

http://www.maximumpc.com|SEP 08 |MAMAMAXIMXIMXIMXIMUUUUMMPPPCC| 65

SUBMIT YOUR IDEA Ever wonder what the inside of a power supply looks like?

Don’t take a chance on destroying your own rig; instead, let us do the dirty

work. Tell us what we should crack open for a future autopsy by writing to

[email protected].

LCD INVERTER

BOARD The maze of

capacitors, regula-

tors, and transform-

ers on the LCD

inverter board spits

out DC current to the

display’s liquid crys-

tals. It also powers

the two cold cathode

tubes on the layer

above it.

CATHODE TUBES

Cathode tubes

span the horizon-

tal edges of a rigid

piece of plastic

that’s patterned

with thousands of

small dots to aid

in the backlight’s

diffusion.

DIFFUSION LAY-

ERS Three flexible

diffusion sheets

help scatter and

spread the glow of

the cathode back-

light.

LCD PANEL Light passes through the panel’s

first polarizing filter, which orients the electro-

magnetic waves along a specific path. This wave

passes through a layer of twisted liquid crystal

molecules, which rotates the wave to allow it to

pass through a second polarizing filter, giving

you an image. To create darkness, the mol-

ecules shift away from their helix orientation

when an electrical current is applied. Thus, no

electromagnetic wave rotation occurs and the

second polarizing filter blocks the light.

Zalman achieves its 3D effect through ste-

reoscopy. On the software level, Nvidia drivers

display two offset images in rapid, interlaced

succession. A third polarization film attached

to the monitor aligns alternating stripes of

phase retardation with the pixels specific to

each image. Each image is converted from lin-

ear polarization waves to circular waves spin-

ning either clockwise or counterclockwise, and

circular polarized glasses worn by the viewer

ensure that only one image is seen per eye.

The illusion of depth created by the overlap-

ping images elicits the sense of 3D.