The December 2022 issue of IEEE Spectrum is here!

Close bar

Could a Cellphone Run on Sun? Not Really, Says Nokia

Charging a mobile phone solely with a built-in solar panel won’t be possible anytime soon.

2 min read
Could a Cellphone Run on Sun? Not Really, Says Nokia

From June to September last year, five people in diverse environments around the world carried around special mobile phones made by Nokia. The prototypes were equipped with thin-film silicon solar panels on their back cover and a data logger to report harvested solar energy. The goal of Nokia's solar charging project was to find out how viable and easy it is to charge a cellphone using sunlight.

The results are disappointing, unless you live in a sunny locale near the equator and are able to stay outdoors most of the day with your phone clipped to your belt or in a holder around your neck. The phones were, at best, able to harvest enough energy to stay in standby mode, but with only 10 to 20 minutes of talk time. An hour of talk time was possible only after a full day’s exposure to the sun. In a blog post, Nokia says that “there’s still some way to go before a workable and care-free solution is achieved.”

The biggest challenge, according to the handset maker, is the limited size of the back cover. What’s more, the amount of charge generated depends not only on amount of sunlight and weather conditions, but also on the user’s lifestyle and the angle of light falling on the phone’s panels.

Two of the project’s testers were inside the Arctic Circle, one was in southern Sweden, one in Kenya, and the fifth was sailing in the Baltic Sea. The best results came from Kenya, where the sun is plentiful, and the tester, a security guard, was often stationary. In 59 days, the guard gained 20 hours talk time or enough standby for 41 days. That's good news given the booming mobile phone market and uncertain electricity supply in most African cities.

In the Arctic, meanwhile, even though the sun shone for 24 hours, the low angle meant a lot of shadows. In 65 days, one tester gained enough energy for 17 hours talk time, while the other harvested 2.2 hours talk time in 49 days. Needless to say, the energy harvested would be zero in the three months of winter darkness.

As per Nokia: “For people who live in parts of the world with constant sunshine, such as Kenya, and who can’t just plug in and load up on electricity, solar charging is definitely an option.”

Nokia launched the first solar-powered phone back in 1997, according to IT World. More recently, Samsung and LG have introduced smartphones with a solar panel in the back cover, but the technology still isn’t mature enough for the mainstream market.

PHOTO: Nokia

 

The Conversation (0)

Deep Learning Could Bring the Concert Experience Home

The century-old quest for truly realistic sound production is finally paying off

12 min read
Vertical
Image containing multiple aspects such as instruments and left and right open hands.
Stuart Bradford
Blue

Now that recorded sound has become ubiquitous, we hardly think about it. From our smartphones, smart speakers, TVs, radios, disc players, and car sound systems, it’s an enduring and enjoyable presence in our lives. In 2017, a survey by the polling firm Nielsen suggested that some 90 percent of the U.S. population listens to music regularly and that, on average, they do so 32 hours per week.

Behind this free-flowing pleasure are enormous industries applying technology to the long-standing goal of reproducing sound with the greatest possible realism. From Edison’s phonograph and the horn speakers of the 1880s, successive generations of engineers in pursuit of this ideal invented and exploited countless technologies: triode vacuum tubes, dynamic loudspeakers, magnetic phonograph cartridges, solid-state amplifier circuits in scores of different topologies, electrostatic speakers, optical discs, stereo, and surround sound. And over the past five decades, digital technologies, like audio compression and streaming, have transformed the music industry.

Keep Reading ↓Show less
{"imageShortcodeIds":[]}