Laptops vary greatly in their energy needs and how they're used (number of hours daily, viewing, uploading, burning DVDs) as well as their age will have a huge effect on power consumption. In general a laptop will require between 20 and 65 watts and the older and bigger it is the higher the power demand.
The dynamics in size and output are continually improving and advances in thin film photovoltaic technology have made way for super portable, flexible solar panels that can be folded up or rolled into easily transportable packages for powering electronic devices.
Size matters when you're considering solar power for a laptop computer whether we're talking about the solar panel or the laptop. Ideally you want the laptop with the lowest energy demand and the solar charger with the highest output for it's size.
The LaptopIf you're in the process of buying a laptop to power with solar energy, buy the most energy efficient model that will address your needs. If you intend to power an existing computer you'll need an appropriately sized laptop solar charger. It's possible that the cost of powering the old dinosaur might be more than buying both the energy efficient computer and enough solar potential to energize it.
A laptop requires energy to be fed into it at a certain rate. To prevent damage to the computer's workings it's important to maintain the flow of energy from the panel to the computer within certain parameters. Either a power center or an inverter and regulator must be installed between the panels and laptop.
The Solar LaptopThe new kid on the block is the laptop sporting it's own solar panel. Yet to be proven in the marketplace the idea is a great one but there might be an issue or two.
Solar panels need bright sunlight and that's not necessarily what the computer wants.
Power output from panels as small as these is minimal. Probably enough to increase user time on a single battery charge but it would take 2 or 3 days to fully charge the battery. If that's all the power you need then this just may be the choice for you.
The Solar Charger
Unless your computer runs on 12V power (and it's highly unlikely that it does) it is not possible to plug the solar charger directly into the computer.
Either you need a 12 volt adapter for the laptop (automotive stores are likely to have them) so that your laptop can use the 12V (orDC) energy.
Or the energy has to be processed through an inverter or converter (usually contained in a power center or power pac) to make it compatible with the laptop. When you purchase a solar charger ensure that a power center accompanies it or is built into the system. Buying the solar cells and power station as a package ensures ease of use and demonstrated compatibility.
Not everyone needs to power their computer for hours per day. If recharging the batteries for several hours (5 or so) to gain an hour or two of computer time works for your needs, buy a charger capable of generating 14 to 20 watts. If you want to run the computer and charge the battery at the same time you'll be better off with closer to 50 watts.
Serious Solar Power for a Laptop
Those who are serious about powering a laptop for "on demand" use in remote and wilderness situations will choose a solar charger capable of generating 50 or more watts.
The following models have made 8 excursions to Mount Everest proving themselves as a reliable power source in the remotest location on earth. They can be found at CT Solar along with even more powerful models.
Standard Laptop Solar Power System At a cost of $990.00 USD this solar charger will provide just over 60 watts. all the power you'll need to run and charge a laptop at the same time.
It's little brother churns out 32 watts in the bright sunshine at a cost of $680.00 USD and will run most laptops that are less than 2 years old and under 15".
The Bottom Line
A portable solar power system that produces enough energy to allow you several hours of computer use per day will easily cost you as much as the laptop itself. A small price to pay if it buys you your freedom.
So far, a computer with an internal solar cell (like those in calculators) that powers the computer independently of any other source of energy, doesn't exist. A laptop requires much more energy to run it than an LED calculator or watch which both use very low amounts of power. Also, leaving a laptop computer in the sun for long periods is not good for it's health.
Solar chargers are capable of producing enough solar power for a laptop now and as nanotechnologists produce smaller and smaller solar cells it won't be long before every laptop has the capability to power itself.
NoteIf your vehicle is facing in a favorable direction, placing foldable panels over the windshield can keep the vehicle's interior cool while they soak up enough sunshine to power your devices.
Enjoy the freedom to upload and edit photos, stay in touch, navigate the wilderness, keep an electronic journal, even access the internet (in many places) all while beyond the reach of electrical sockets.