Does Steve Jobs have designs on harnessing the power of the mighty sun? Apple has submitted a patent application for a new system to control multiple solar cells on a portable device. But don’t throw away your iPhone charger just yet.
Some portable electronics already try to take advantage of onboard
solar power systems, but size restrictions limit the number of solar
cells that can be placed on them, relegating the technology to devices
with very low energy needs. In its patent application, Apple proposes
layers of solar cells that sit underneath a display; in devices like
the iPhone or the much-anticipated Apple tablet, that would mean a
large percentage of the device’s real estate is capable of generating
electricity.
But based on some back-of-the-envelope math, the dream falls short, at least with today’s solar technology.
One square meter of the earth’s surface receives about 1,000 watts an hour
from the sun in ideal conditions, and the iPhone screen is about .003
square meters. Even the most advanced experimental photovoltaic cells
boast only around 40% efficiency, so a solar iPhone could generate
around 1.2 watts per hour (1,000 watts/hour * 0.003 * 0.4). That’s well
below the 5 watts per hour that the standard iPhone charger pulls in.
Still, a solar iPhone would have an increased battery life, and the
prospect of stepping into the sunlight with your phone on its last sip
of juice and watching the power meter creep up a few notches is
certainly alluring. And an iPhone studded with solar cells would be a
tantalizing piece of eco-bling: What better way to show off your savvy
greenness than to whip out one of those babies to glitter in the midday
sun?
