Solar Power

As solar technology has improved, the components required to generate electricity from solar power have scaled down in both size and weight. People today expect their phones, PDAs, even game devices to be portable. So why not your power generation?

Well, that's already possible. Portable solar panels now come in sizes small enough to fit in a fanny pack or a glove box. These devices can be opened up during the day, exposing their solar panels to sunlight. This charges the photovoltaic cells, and then you attach your electronic device, such as a cell phone or PDA, to the solar panel via an adapter.

Portable panels almost exclusively utilize thin-film technology, where the solar cells are part of a film of material that adheres to a fabric backing. Portable panels come in a variety of voltages, and you'll want to be sure to get one with enough power for the device or devices you plan to use.

For instance, cell phones, personal digital assistants (PDAs) and digital cameras typically require a smaller charge (3.5 to 6 volts). However, laptop computers and other power-hungry devices can require a much larger load, up to 50 or 75 watts. And watts are a much larger energy load than volts.

When choosing a portable solar panel, the very first thing you need to do is figure out what you'll be charging. How many watts does each device require? Usually the adapter for the device will give you the wattage generated, or at least the amps and volts. Amps x volts = watts.

You need a solar panel, or combination of solar panels daisy-chained together, that can generate at least the wattage for your device. Smaller wattage ratings will not fully charge the battery on your device, and many batteries maintain a "charge memory". If not fully charged, they'll remember that, and not fully charge the next time.

One other thing to consider, especially if you plan to use one solar panel for multiple devices, is that it's possible to overcharge some batteries. Li-ion batteries should have a built-in controller chip, because this type of battery can explode when overcharged. Definitely something you want to avoid.

Other batteries can be damaged by overcharging. Look for chargers that have an indicator light for fully charged status.

One other thing to consider is the time required to fully charge your device using solar power. Simply put, it's going to take longer. Any solar panel that's truly portable is by definition going to be smaller than the ones you mount on your roof. Smaller sunlight collection areas equal less juice, equals longer charging times.

Typically, you're looking at 4-8 hours to charge your device, depending on the size of your portable solar panel and the energy requirements of your device. Of course, your device can be used while it's charging on the panel-it'll just extend the time to full charge a little longer.

Portable solar panels are a wonderful, fairly new innovation. But as with everything in life, there are trade-offs. You give up a certain amount of power and charging time for the portability. But considering the potential benefits of having a working cell phone in the back country, most people will probably vote to have some power available.