|Fig. 1: This shows the amount of solar energy in hours, received each day on an optimally tilted surface during the worst month of the year for the United States of America. [1,2] (Courtesy of the U.S. Department of Energy)|
Harnessing solar energy through solar panels has come a long way from it's early beginnings in the 1940's and 50's. Today we see solar panels all over the world being used to lower energy costs. Drive through California neighborhoods and solar panels can be seen running along rooftops to provide supplemental energy to that house. Solar panels are even being used to power technology such as flashlights, calculators, and even laptops! This got me thinking about other devices that could potentially benefit from running off of solar energy. If it's possible to run a laptop purely off of solar panels, what other everyday technologies can be powered by solar panels? What are the limits of how much energy can be generated from these portable solar panels?
After hearing about the solar powered laptop, it immediately got me thinking about the possibility of installing solar panels in cell phones. Unlike laptops, almost everyone uses a cell phone to communicate everyday and even more so most teenagers are glued to their devices while surfing the internet or playing mobile games, as well. A big problem with a lot of phones today, iPhones specifically in my experience, is that the battery life cannot keep up with the amount of usage the cell phone receives everyday. I thought that adding another source of energy collection that can be used on-the-go would be very beneficial to someone who uses their phone to the point that the battery has died before the day is even over.
Before researching the subject, I thought that solar panels were too big to fit on such small portable devices, but when I saw the laptop that ran off of solar energy my view point changed. The solar panels that power the laptop are foldable and lay flat on top of each other when not in use. This makes the laptop much more mobile than I originally thought. I can picture a phone that has solar panels that unfold from the back of it, allowing it to still fit in your pocket when not in use. Solar panels have dropped dramatically in price over the years as well, and are continuing to drop. This makes it an ideal time to use solar panels because it would cost less than $.50 to install per watt. For an iPhone that uses a charging cable at 12 watts, you can effectively charge the your iPhone on-the-go with solar panels that only cost around $6.
Before you get too excited about slapping on a solar panel on your phone so you can cut that damn charging cord in half and throw it away, there are a lot of things that can make solar panels less appealing.
First, solar panels are not exactly durable enough to endure as much wear and tear as cell phones do. Although they are built to endure harsh weather, the solar cells are protected by glass. If you've ever dropped an iPhone or seen one dropped, you'll see that glass is not exactly the most durable material especially on devices that are susceptible to being dropped from slippery hands over and over. It's probable that solar panels would break fairly quickly after being installed on an iPhone.
Another big issue looming over solar panels is how drastically the amount of sun exposure fluctuates depending on where you live. Refer to Fig. 1. If you live in Arizona or Southern California, solar panels make a lot of sense. However, if you live in Seattle where it rains often, you wouldn't be able to harness near as much solar power because "[solar panel] output can be decreased to 20-30% of its rating if panel is shaded as much as a leafless tree branch." 
Perhaps in a few years when solar panels become a little more compact, durable, and more effective at harnessing sunlight we'll see them used for more everyday technologies.
© Dalton Schultz. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 K. Sedghisigarchi, "Residential Solar Systems: Technology, Net-Metering, and Financial Payback," IEEE 5420778, Proc. Electrical Power and Energy Conference (EPEC), 22 Oct 09.
 "Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors," U.S. National Renewable Energy Laboratory, NREL/TP-463-5607, April 1994.