Voltaic Systems Solar Backpack: 11/20/2004
By: Allison DeFrees
While preparing for a trip to Spain a few years back,
Australian inventor Shayne McQuade discovered a portable solar product that
electronic devices. While it worked, he found it rather bulky and unmanageable,
as it required him to set aside long periods of time when he could leave
it out in the sun. But it got him thinking about solar power, and about
the possibilities of harnessing it for portable use.
In imagining the possibilities, McQuade considered making solar powered jackets, tents, and other clothing, before fastening onto the idea of a solar backpack. A backpack is purposefully built for portability, with a ready-made surface for solar panels and compartments for carrying the battery and various electronic devices and sundry personal articles. In addition, McQuade realized that it makes more sense to place the panels on a backpack, which can be worn or removed and placed in the sun on a cold day.
In his research, McQuade learned of a new technology, flexible solar panels, which were being used by the U.S. Army to service troop needs out in the desert sun. He looked at the application for this kind of engineering, and realized that it enabled its users to pull in a great deal of energy—enough to light up a campsite, in fact, and certainly to power laptops. However, it also required the use of large-scale panels that users fold out onto a large, flat surface. One would have to fold out enough panels equal to the size of a large table in order to power a laptop computer.
Like the first charger McQuade tried out, the flexible panels must be set up and left out in the sun while they charge an electronic device. Furthermore, most flexible panels are thin, stainless steel sheets that are sprayed with amorphous silicon and the connected to one another with wires, and while they are lightweight, they are not particularly sturdy. In fact, you can shoot a bullet through them and they will still work, but if you continuously bend or crease them, as you would on a bag, they will gradually fail. Despite the initial hurdles in durability, the portability of the solar panels got his mind racing, and served as the inspiration for what would become the solar backpack.
McQuade turned to more traditional solar cell panels, which are rigid in form. Companies like BP, Shell Oil and Sharp all produce solar panels. McQuade found that their panels were typically pasted onto bases that weren’t sturdy enough to be mounted on the back of a backpack. In fact, he found that he could bend the panels with his hands, if he tried. Bending the solar panels causes cracks and breaks within the panels, which would in turn weaken the ability of the cells to generate a solar charge. Or, if the panels were sturdy—you can mount solar cells onto any solid surface--they were too heavy to carry around on a backpack. What he eventually discovered was a plastic aluminum “sandwich: which was both lightweight and extremely stiff. The panels are then sprayed with epoxy, which protects the panels from the weather and from scratches and dents.
When I tried to bend one of the panels, it was like trying to budge the steel cables on the Brooklyn Bridge—not a chance. The FAQ section on Voltaic Systems’s website indicates that, were you to place the panel over a rock and then stand on either side of the panel, it might break, but this gives you the idea of its durability. In addition, the epoxy surface is waterproof and UV resistant. Furthermore, if a scratch were to mar the surface, the epoxy substance will melt the scratch away when placed in sunlight.
The hard solar panels McQuade built for his product are cheaper, stronger and more efficient than flexible panels. Cell efficiency in the solar panels is 17%, which means that, when the panels are facing the sun (and they will also charge on cloudy days, though with less efficiency), they ultimately carry to the battery pack 17% of the energy of sun’s rays hitting the panels. This amount of power enables a typical cell phone to fully charge, from an empty state, in 4-6 hours.
Once he found the right panel, however, McQuade was left with the problem of making the bags attractive. “The difficult thing about this is the manufacturers weren’t used to an interest in aesthetics,” he noted. As with the cells themselves, and the battery pack that would be hooked up to the cells, he was looking for a bag that would be both strong and lightweight.
Once he had that idea in mind, he purchased a basic sports backpack and had a seamstress sew three solar panels—each panel is comprised of 24 pieces of 1⁄2-volt solar cells which generate up to 4 watts of power, wired together in a series which results in a total of 12 volts—onto the back of the backpack. He started carrying it with him everywhere—throughout New York, Australia, Europe, Asia—and made adjustments and improvements all along the way.
The final product is a smart, sleek black backpack with wide, comfortable, adjustable shoulder straps, two small pouches—one inside the backpack, and one mounted on one of the straps—for cell phones and MP3 players, two side pockets, a separate zipper compartment for the battery and accoutrements, such as a car charger device and various wires and power adaptors, and a flat, steel-reinforced zipper pocket that allows you to slide the solar panels in and out of the bag. That way, since solar panels won’t break barring a conscious attempt to do so and rarely wear out—a panel lasts from 5 to 20 years when set out in the sun without cease—they can simply be removed when you decide to get a new bag, and then inserted in the new bag. In addition, consumers can also purchase padded inserts for laptops, though the natural size restrictions that a backpack creates, coupled with current solar power technology, doesn’t allow for a laptop to be charged via the backpack’s solar charger.
The mechanism of the solar charger is remarkably simple. McQuade has created a snap-sized indicator sticking out from the lower right hand pocket of the backpack which lights up when the solar panels are actively charging. The indicator is hooked up by wires to the 2200mAh Lithium Ion battery, which is in turn hooked up by wires to the solar panels. When a button is pressed at the top of the battery, a light comes on to indicate the amount of charge left in the battery: green indicates that the battery is fully charged, amber means there is some charge left, and red indicates that there is no charge.
A wire also runs out of the battery and plugs into, via universal and custom adaptors, cell phones, iPods, global positioning devices, PDA’s, digital cameras, and other electronic devices. In addition, included with the backpack is a LED torch which provides an impressive amount of light—and a second torch that is built directly into the battery pack.
The solar power panels, when faced into sunlight, can directly power most small electronic devices, or it can be used to charge the Lithium Ion battery, which holds the charge even when out of the sunlight.
The Lithium Ion batteries are very lightweight, and are more environmentally friendly than nickel metal cadmium batteries. Furthermore, they last through thousands of charging cycles. Also included in the backpack is a 12-volt car charger socket, so that if an individual has a car charging device for his or her phone, it can be plugged directly into the socket, which can be connected straight to the solar panels. Note that the car charger socket works independently of the battery, and may be plugged either directly into the solar panels, or into the battery pack. Finally, the Voltaic Systems backpack comes with an AC travel charger (11/240V 850mA) and a DC car charger which allow for the battery packed to be recharged out of the sun, when desired. Thus, rather than simply being a solar bag, it also functions as an electronic bag, and is as useful for getting around the city as it is off the electronic grid.
To deal with the dizzying array of plugs for charging various devices, McQuade has created a series of adapters, and also has included a voltage converter on two different battery packs. The standard battery pack produces 5, 6, or 7.2 volts. The alternate battery also has the 5- and 6-volt charges, but offers a 3.7-volt setting, as opposed to the 7.2 volts. Which pack you choose depends upon your individual needs.
The 5-volt level is the charging rate for most cellular phones and USB chargers. 6-volts, which is the equivalent of 4 double-A batteries, charge such things as 2-way radios and global positioning devices. The 3.7-volt setting charges the equivalent of 2 double-A or triple-A batteries and charges such items as CD players, radios, and walkmans, while the 7.2-volt setting allow you to charge larger devices, including some digital cameras and the latest 4th generation iPod.
At present, the 11 cell phone adapters will work on a wide range of cell phones, including all of the most basic phones from Sony Ericsson, Siemens, ,and the like, and list is constantly increasing. The Voltaic website includes an up-to-date list of devices that can be charged using the solar backpack. In addition, the backpack comes with 5 different PDA adaptors and a range of universal and camera adaptors. Standard with the bag will be four different adaptors, which cover of the most popular cell phones, and seven universal plugs. Additional, less common, plug adaptors may be ordered from the website. Furthermore, while the initial stock includes only the black pack with orange stripes, future orders will allow for a variety of color choices and styles.
McQuade likened the lithium battery in the backpack to an “electronic match.” With life set at an ever-increasing pace, mobility is key, and an electronic match to power our mobile lifestyles is an optimal blend of versatility, comfort and cool.
The bags are available on the website, at www.voltaicsystems.com, a few other websites, and in select stores in Los Angeles, New York, and San Francisco, all of which are listed on the website. The retail price for the backpack is $229, plus shipping.
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