Cloudy Forecast for Solar-Powered Radios

Solar-powered radio could be an attractive, ecological alternative to battery-operated receivers, particularly for outdoor activities.

But the engineering has yet to catch up to the concept. None of the three portable radios we tested--the Freeplay S360 Self Powered Radio, the Solar Sun Visor Speaker Radio and the Kaito World Receiver--is reliable or convenient enough for recreational use, but all could come in handy during emergencies.

The radios not only operate off light rays, they also store sun power for use indoors, at night or when the clouds roll in.

The base technology is not new, but the application is. Solar cells have been used to generate electricity since the 1950s.

A basic solar cell is made of two layers of silicon, one with an overabundance of electrons. When light hits it, electrons break loose and flow toward the less-endowed layer, which in turn produces energy.

Because the process is expensive, solar-powered consumer devices are most often small gadgets such as calculators that draw only tiny amounts of power.

Power-hungry radios pose a challenge for solar.

Two of the models tested came equipped with crank generators to provide an alternative energy source when out of the sun for prolonged periods.

Even with the storage capacity and crank generators, the lame performance of these radios relegates them for use during emergencies when batteries might be scarce or by those for whom devout environmentalism is a way of life.

All the radios were tested in direct sunlight. Then they were turned off for one hour to give them a chance to store power. They were brought indoors, where they sat for 24 hours, and then were turned on again to test how long they could operate on stored electricity.

Freeplay S360 Self-Powered Radio

London-based Freeplay has earned a good reputation for its products. It began in the mid-1990s with a crank-powered radio designed to get information about AIDS prevention and treatments to areas in Africa where electricity is scarce.

The crank generator on the S360 worked well during testing, giving hours of AM/FM (mono only) operation for about a minute’s worth of crank turns.

The solar cell on top of the weighty unit also was effective as long as it was in direct sunlight.

But the solar storage test did not go well. According to the manual, “sufficient” exposure to sunlight will charge the unit’s built-in, NiCd batteries.

An hour clearly was not sufficient--it allowed for only a few seconds of radio play the next day.

Otherwise, the sound of the S360 is clear and of nice fidelity. The unit is handsome and seems sturdy. It came with an AC adapter to allow it to play indoors without use of the hand crank or solar energy and to charge the NiCd batteries.

Solar Sun Visor Speaker Radio

Here at Tech Times we have tested numerous products that could be described as dorky. But Solar Sun Visor opens up whole new worlds of dorkiness. This item makes pocket protectors look as if they could appear on the fashion runways of Milan.

The bright red, plastic visor has a solar panel embedded in its bill. It also sports a telescoping, metal antenna that makes one look like a reject from “My Favorite Martian.”

On its right side is a fold-down speaker unit that contains the AM/FM dial and a combination on/off volume knob.

The package calls it “Unique!” One would be tempted to say, “Let’s hope so,” except that the Solar Sun Visor--geeky as it is--works pretty well.

The AM/FM (mono only) radio pulled in local stations clearly and, best of all, its storage capacity was relatively impressive--an hour in the sun produced almost a full hour’s worth of operation indoors. The unit weighs only about 4 oz.

The Solar Sun Visor’s main drawback, in addition to its looks, is that it has no fallback power source.

The sound fidelity is not great, and because it comes from a little speaker with no outlet for an earphone, it’s hardly private.

So what’s the Solar Sun Visor good for? Maybe listening to a ball game while doing some gardening in the backyard. Alone. Behind a tall fence.

Kaito World Receiver

Hopes were high for this unit, especially as an emergency radio. Not only does it receive AM and FM (mono only), it also tunes into shortwave, TV and weather bands.

But the performance was dismal. It did not work via solar power, even when sitting in direct sunlight. After an hour in the sun, it was still a no-go.

The built-in crank worked a little better. After several minutes of arduous cranking, the radio played for less than a minute, which was not enough time to figure out the bewildering band-switching arrangement.

Even when plugged in via the AC adapter, the band switches remained mysterious. But it was so difficult to pull in clearly even a local FM station on the Kaito World Receiver that it hardly mattered.

The unit also can be operated, supposedly, with conventional AA batteries.

It didn’t seem worth trying.

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David Colker covers personal technology. He can be reached at david .colker@latimes.com.

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Freeplay S360 Self Powered Radio

Price: $70

The good: Solar cells work well in direct sunlight, crank unit provides enough stored power for hours of operation

The bad: Solar cells store almost no usable power after an hour in the sun

Bottom line: Good for emergencies

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Solar Sun Visor Speaker Radio

Price: $27

The good: Impressive power storage, lightweight

The bad: No fallback power source

Bottom line: Convenient but dorky

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Kaito World Receiver

Price: $50

The good: Receives shortwave, TV and weather bands in addition to AM/FM

The bad: Flimsy, difficult to tune, crank works terribly

Bottom line: Don’t bother