October 1954 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
You say "solar battery, "I
say, "solar cell." The nomenclature has evidently changed since the time when commercializable
solar cells first came on the scene. Conversion efficiency rates of 6% are heralded,
enough they say so that "...a wafer-thin slab of crystal, 4 ft. x 15 ft., either
resting on or built into the roof of a house, could supply enough current to operate
all the lights, stove, refrigerator, and other appliances in the house - 24 hours
a day." Even with today's efficiencies in the 20% realm, you couldn't power much
of a house on a 4 x 15 ft. array. Maybe they meant if you had a gas lights, and
a gas powered refrigerators( yes, they exist) and a gas stove!
See also "Silicon
Solar Cells" in the November 1973 and "Power from the
Sun with Silicon" in the February 1973 issues of Popular Electronics.
Sun's Rays Used in New Invention
The universe's greatest source of potential
power - even greater than the atom - has been harnessed experimentally and offers
great promise for future commercial applications.
A solar battery, the first successful device to convert useful amounts of the
sun's energy directly and efficiently into electricity, has been demonstrated by
the Bell Telephone Laboratories.
With an amazingly simple - looking apparatus made of strips of silicon, the scientists
demonstrated how the sun's rays could be used to power the transmission of voices
over telephone wires. These strips are extremely sensitive to light. Linked together
electrically, they can deliver power at a rate of 50 watts per square yard.
G. L. Pearson, D. M. Chapin, and C. S. Fuller of Bell Labs checking
sample devices for amount of electricity derived from "sunlight" (lamps).
The solar battery, composed of strips of specially prepared silicon.
has been used to power transmission of voices over telephone wires.
A toy Ferris wheel which receives its power from light falling
on a tiny piece of silicon. It was used to demonstrate principle.
According to the Laboratories, it is possible to achieve 6 percent efficiency
in converting sunlight directly into electricity. This compares favorably with the
efficiency of steam and gasoline engines in contrast with other photoelectric devices
which have never been rated higher than about 1 percent.
With improved techniques, the Bell Laboratories' scientists expect to be able
to increase this efficiency substantially. Nothing is consumed or destroyed in the
energy conversion process and there are no moving parts so, theoretically, the solar
battery should last indefinitely.
The specially prepared silicon used is obtained, originally, from common sand,
one of the world's most abundant materials. Silicon is a semiconductor, chemically
related to germanium, the material used in most transistors. Silicon has a much
greater electronic stability at higher temperatures than other semiconductors.
Sunlight provides the power to turn this motor-driven wheel held
by D. M. Chapin, one of the three inventors of the Bell solar battery.
Detailed and close-up views of the razorblade-sized silicon strips.
The strips are connected in series in device shown here.
Although work is still in the laboratory stage, actual use of the solar battery
in telephone work is a strong possibility. For example, silicon solar batteries
might be used as power supplies for low-power mobile equipment or as sun-powered
battery chargers which could be used at amplifier stations along a rural telephone
system such as that now being tested at Americus, Georgia. This system, using transistors,
points to greatly increased service on rural telephone lines without the addition
of new wires.
Although the sun supplies over a thousand trillion (1,000,000,000,000,000) kilowatt
hours of energy daily-comparable with all the reserves of coal, oil, natural gas,
and uranium found on earth-man has never been able to convert more than a small
fraction of this energy directly to his use.
WADC Engineers Also Convert Sun's Energy Into Electricity
Another successful attempt at converting light into electrical energy has been
reported by the Wright Air Development Center in Ohio.
Their method differs from that of the Bell Labs development in that cadmium sulfide
was used in place of silicon. Donald C. Reynolds and Lt. Col. Gerard M. Leies discovered
the excellent properties of this substance while collecting data for rectifiers.
The barrier layer cell, as developed by the WADC scientists, consists of cadmium
sulfide processed into crystal form. The crystal used in the first model was about
the size of a sugar cube but it need be only wafer thin to work efficiently.
Although the first model was crude, the inventors foresee that with several improvements
and by hooking a number of the units into relays it is possible to step up the voltage
to unlimited quantities. According to their report, the conversion powers are so
great that a wafer-thin slab of crystal, 4 ft. x 15 ft., either resting on or built
into the roof of a house, could supply enough current to operate all the lights,
stove, refrigerator, and other appliances in the house - 24 hours a day.