Solar Power: Sign of the Times

As technology improves, solar-powered changeable message signs and arrow boards are surging in popularity

Article December 28, 2000
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A number of things
are coming together to contribute to the increased use of
solar-powered arrowboards and changeable message signs (CMSs). A
motivation to find and develop alternative fuel sources is one
factor. This motivation has its influence in the oil shortages
of the 1970s. There also is a growing awareness of the
environment and a concern that pollution from traditional
sources of energy is adversely affecting our ecosystem.

Technological advancements also are making use of solar-powered
CMSs and arrowboards more practical. Improvements in the
manufacturing of photovoltaic cells--devices that generate
voltage when exposed to radiant energy such as the sun--have
resulted in lower cost of the cells, thus making solar power
more affordable.

Another technological advance is
high-intensity light-emitting diodes, commonly known as LEDs.
LEDs have many advantages over traditional incandescent lamps.
They operate on very low voltages, making them more energy
efficient. They can be designed to emit a specific light color.
Incandescent lamps emit only a white light. They also are very
rugged and durable.

Changing social views concerning the
environment and technological improve- ments have lead to
increased uses of solar-powered arrow- boards and CMSs. Now that
they are available, they are proving their worth over gasoline-
or diesel-powered boards. Signs powered by fossil fuels use an
engine and a generator to produce its power, thus requiring more
manpower in refueling. With more moving parts and a reliance on
consumable fuel, diesels have a greater potential for power
failure. This results in more time spent fixing break-downs and
performing maintenance. Breakdowns and fuel exhaustion will
cause the sign to cease functioning, which leads to potential
safety problems.

Depending on the model, solar- powered
signs can last 18 to 30 days without sunlight. And overcast days
are not a problem because enough ultraviolet rays and infrared
radiation is coming through the cloud cover to power the signs.
With only a periodic check of the battery banks required, less
man-hours are spent maintaining the units.

The following is
a partial listing of some available solar-powered sign boards.

Addco

Addco Manufacturing, St. Paul, Minn., offers two
models of CMSs, the all LED DH1000 ALS and the LED-DOT sign.
Both combine the technologies of LED, solar power and batteries
to provide signs powered only by the sun. Each feature solar
panels that rotate 340 deg and tilt from 0 to 40 deg to optimize
the capture of the sun's rays. The ALS features enhanced
legibility, reduced glare and increased contrast in the
character display through the company's Eclipse system.

The
LED-DOT sign comes with a fluorescent flip-disk technology for
use in the daytime, and the LED technology for nighttime or
low-light use. The company claims that this sign uses 50% less
electrical power than a conventional flip-disk diesel- powered
sign.

Addco also offers a portable traffic light signal
powered by solar energy. The system consists of two signal
trailers, which constantly communicate with each other via a
two-watt radio link. They are designed for one-person set-up in
less than 20 minutes and offer an alternative to flaggers and
pole signals.

Allmand Brothers

Makers of
Eclipse--solar-powered flashing arrowboards--Allmand Brothers
Inc., Holdrege, Neb., has modified its product by incorporating
the use of LED lamps. Halogen lamps also are available. This
improves the unit's energy efficiency. The Eclipse uses two,
three or four self-regulating solar panels to charge commercial
marine deep-cycle power batteries. The panels are available in
either 50-, 75- or 100-watts and optional panels may be added to
increase the charging of the batteries. When the arrowboard is
in a stowed position for travel or storage, the panels remain
facing upward to collect energy and charge the batteries.

Fully charged, it can run unattended for weeks. A bright red
flashing low-voltage warning light indicates when the batteries
need recharging, and is visible for drive-by inspections. An
on-board circuit monitor insures optimum battery life by
shutting down the unit before the voltage drops to a
battery-damaging level.

The company also offers a retrofit
kit, which can be used to convert a gasoline or diesel-powered
board into a solar-powered one.

Models available include the
2200/SE ALT, 15-lamp Eclipse and the 2200/SE APF 25-lamp
Eclipse. Both come with either LED or halogen lamps.

American Electronic Sign

The company has recently introduced
a smaller solar-powered LED-hybrid CMS called the Trilux-1
Junior PCMS. It is closer in size to an arrowboard than a
full-sized CMS, but will still display three lines of text with
eight characters per line. The company claims the smaller size
makes it ideal for cities and counties that do not have the wide
shoulders typically found on the interstate highways. The
full-matrix sign allows various character heights from 10.5 in.
to 36 in. and traffic safety symbols to be displayed.

The
display utilizes amber Indium -based LEDs for illumination in
combination with a retroreflective pixel sheeting material. The
sheeting helps to broaden the viewing angle and provides a
display that will not fade in color intensity. This also
provides a programmable default message that is visible in
daytime or nighttime.

The product features a programmable
touchpad controller that allows the user to scroll through a
list of preprogrammed text messages and symbols. It also comes
with an optional radar device that will display a passing car's
speed along with a safety message. The radar software will log
information such as the number of cars that passed, mean speed,
maximum speed and minimum speed.

American Signal Co.

This company offers the CMS-GP432 general purpose CMS. It
features an all LED full-matrix display and can be charged with
either solar power or diesel power. The solar system has a
battery life of 30 days. Graphic options for the display include
27 MUTCD symbol signs, nine character fonts featuring character
heights from 9 in. to 28 in. There are 199 pre-programmed
messages and 199 user-defined messages, as well as full-height
chevrons or moving arrows. The product also has the ability to
flash lines or the entire message. Optional features include
remote control via a cell phone, a pick-up truck-bed-mount sign
support system including adjustable sign height and rotation,
and radar activated message interrupt and on-line sign-speed
display.

Also available is the CMS-T321 Hybrid portable CMS,
which employs amber LED and Flip Dot display technologies. Like
their other product this can be powered by either solar or
diesel, and has a solar-charged battery life of 30 days. Other
options include cell phone remote control and radar activation.

Display Solutions

Display Solutions offers three models
of CMSs, the Sunray 340, 345 and 380. All models feature a
default warning indication if the batteries become discharged,
an electro-hydraulic raise/lower mechanism, a single-board
processing unit to simplify trouble shooting and repair, moving
arrows and chevrons and over 200 pre-stored messages.

The
company also offers the Sunray Hybrid, an LED CMS with flip
disks. This product has many of the same features as the other
three.

They also make a solar-powered arrowboard with a
90-watt solar panel mounted above the sign case. The panel can
be tilted 90 deg to optimize charging. Its batteries provide 30
days of single arrow operation without recharging. The
98-in.-wide x 48-in.- high sign panel uses LED lamps, which are
visible at 17 deg from one mile.

Precision Solar Controls

Their Solar Message Center is a portable, CMS, which uses
LED lamps and solar panels. It is capable of operating
independently of the sun for 30 days with 2.5 hours of good sun
required for each additional day of operation.

The company
also offers its Solar Mobile Traffic Monitor for use by police
departments to promote speed limit compliance. As motorists
approach the unit their speed is displayed on the screen. It is
trailer mounted and incorporates LED technology in its 20-in.
character display. The monitor also has the capability of
gathering and classifying pertinent vehicle data. The solar
panel array is sized to provide one day's system power supply in
just two to three hours of good sun. The battery bank is sized
to provide 18 days of continuous operation with no sun.

The
company's solar-powered Arrowmaster is an arrowboard, which can
operate for 30 days without the sun. Whether in an operating or
a travel position, the solar panel is positioned for maximum
charging capabilities.

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