Solar-Powered Radio: Tune in to the Sun!

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NORMA MORRIS
LEFT: WBNO's solar array contains 33,600 photovoltaic cells that convert the sun's rays into electrical power. The low brick building in the background is the studio. RIGHT: Batteries store surplus electricity. Hoods and vents dispose of hydrogen gas, a byproduct of battery chemistry.

Bryan, Ohio–located in the flat, northwestern corner
of the Buckeye State, 50 miles west of Toledo–is
nobody’s idea of “Sun City.” The area has rainy summers… long, harsh winters… and cloud covers that manage to
look ominous even when they’re not dropping rain
or snow.

It was precisely this no-quarter-given climate, however,
that led to the decision to locate the world’s first
commercial solar-powered radio station in Bryan. The
concept’s backers felt that, if the enterprise could
succeed in such an obviously “nonsolar” location, it would
be viable most anywhere. So, to prove the point, WBNO-AM (a
500-watt, dawn-to-dusk operation) transferred its
electrical allegiance from Toledo Edison to the sun on
August 29, 1979.

Better Than Expected

The $300,000 experiment, which is expected to run for the
next 20 years, was designed and is being monitored by the
Lincoln Laboratory at the Massachusetts Institute of
Technology under a grant from the U.S. Department of
Energy.

At the heart of WBNO’s new power system is a one-third-acre
array of photovoltaic cells–33,600 of them in
all–that convert the sun’s rays into direct-current
electricity. At noon on a clear day, the setup can produce
over 15,000 watts… far more power than the station
requires.

In fact, Luke Thaman, WBNO’s general manager, reports that
the early operating results have been much better than
expected. During the course of its first six days of solar
broadcasting, the station required 159 kilowatt hours…
while the sun-cells produced 170.

In addition, significant quantities of power have been
generated, Luke says, even when the sky is partially
obscured by cloud cover and rain. Lincoln Lab’s engineers
estimate that the system will furnish as much as 80% of the
station’s electrical needs on a year-round basis…
although–at the time that this magazine went to
press–the actual amount of power provided by the
solar cells was already a full 86% of the radio station’s
requirements!

How They Did It

The solar array beside the station is made up of seven rows
of south-facing galvanized steel racks. To minimize
shadowing, the rows are placed 12 feet apart, and the
racks–which are bolted to concrete blocks and
anchored to the ground with steel augers–can remain
stable in 100-MPH winds. The cells themselves are arranged
in modular panels of 42 each which are, in turn, bolted
onto the racks. If a single unit is damaged, the entire
module is replaced.

To qualify for the project, WBNO had to install a new
solid-state transmitter, provide equipment for converting
DC electricity into AC, and build a storage room for the
monitoring machinery and the batteries that hold the
surplus power the solar cells often generate. The station
management also had to agree to make the site–and
their research findings–open to the public.

Because the electrical flow from the cells varies in
strength, the system employs four large
batteries–similar to those used in diesel
locomotives–to store the excess electricity. In the
morning, before the sun is strong enough to activate the
cells, the station draws its energy from the storage units.
Fully charged, the batteries can keep WBNO broadcasting for
about a day and a half, and when they’re charged up to 90%
of their capacity, an automatic control adds on
newsroom, studio, and production room loads. If the added
drain doesn’t deplete the surplus being produced, parts of
the panel array are automatically disconnected until
they’re needed again.

Automated Performance

The system is so completely automated that it doesn’t even
require on-site experts to keep it going. A 50-channel data
logger keeps track of all relevant weather and performance
information and records it on a small cassette, which is
mailed to the Lincoln Laboratory once a week for analysis.
If any part of the system malfunctions, an alarm alerts
station personnel to shut off the panels until the trouble
can be corrected. (Reverting to the station’s normal source
of electricity–the local power company–is as
simple as turning a switch.)

One of the big questions that still must be fully answered
is how well the solar array will function during a heavy
snow season. The designers say that the sun’s relation to
the earth in winter will make the cells even more efficient
than in summer… and those same experts are counting on
the sun’s rays (and the electrical activity within the
cells) to melt the snow before it can accumulate on the
tough polyvinyl shields that cover the modules. Although
this past winter was a mild one, WBNO’s experience during
the few big snowfalls indicated that the MIT designers’
theories are correct: The snow melted away from the solar
cells–without assistance–within one to two
hours.

Right now, the main drawback to the widespread use of
photovoltaic cells is their cost. Although the devices are
made primarily of silicon–an abundant element–the
cells can’t be mass-produced inexpensively.  However, the costs are going down. The company that
supplied cells for the experimental station (Solarex, Inc.
of Rockville, Maryland) has since reduced the price to
$9.00 a watt.

Finally, we’re proud to say that–as befits such a
natural, sun-powered operation–WBNO is a country
music station… which also broadcasts MOTHER EARTH NEWS’ radio
show.