A smarter method of charging laptops
Intel has come up some smart solar chargers to power laptops and tablets with solar energy at far lower cost than traditional systems by using a unique combination of micro-controllers and other circuitry to provide direct current from panel to device.
John Tompkins, who works in Intel’s prototyping lab, recently completed a project bringing energy harvesting to education within developing nations, where power infrastructure simply doesn’t exist. The World Vision “Spark” project, which brings Classmate PC laptops and Internet to students in developing countries, uses the traditional method of converting sunlight into electricity. But Tompkins and his team have developed a Smart Solar Charger (SSC) that is both more power-efficient and affordable.
Direct from the source
Typical solar charging systems today involve complex systems with a charge controller that feeds direct current (DC) power to a bank of lead-acid batteries, which connect to an inverter that outputs alternating current (AC) power (like what comes out of your wall sockets).
All of those conversions are not very energy-efficient, says Tompkins, who also cites the high cost. “Any time you manipulate power by controlling its voltage, storing it in batteries or converting it to AC, the system uses a little power as it goes downstream and reduces the system’s overall efficiency.”
What the SSC does differently is take DC power from the solar panels to directly charge the device. This not only eliminates the need for bulky AC/DC conversion hardware, such as bulky and expensive lead-acid batteries, but also enables computer-based education in some remote areas where it’s impossible to transport large equipment.
“By eliminating the charge controller, batteries and inverter, we’re providing a much more efficient and cost-saving solution,” says Tompkins. “The way we look at it is: there is already a battery in the laptop; we are just utilizing the battery that already exists on the platform and not adding another layer of batteries,” says Tompkins.
Lighting and appliances rely on AC power, but computers require DC power, which is why many electronic devices come with a charging brick. In designing an improved way to charge computers using solar power, Tompkins’ team had the freedom to design a system with a specialized purpose.
“Since our goal is to charge DC devices, we can take a different approach,” explains Tompkins.
Although the power from the sun is DC, the SSC ensures that the electrical output is adequate to charge one or more laptops, as solar-generated energy does not provide a constant voltage due to changes caused by cloud cover or moving shadows. Such power fluctuations could damage the device’s power circuit.
“The SSC prevents this from happening by only turning on the power ports when there is enough power from the panels to support 100 percent what the laptop needs,” Tompkins says.
This seemingly more simple system also allows it to be much less expensive to produce and maintain. Tompkins estimates the cost to be a couple thousand dollars to power 16 to 20 Classmate PCs, compared to the tens of thousands of dollars for a traditional system. A single lead-acid battery alone costs $600 to $800.
Future versions of the SSC are expected to accommodate devices that require only 5 to 19 volts, like smartphones, tablets, displays or even items that do not have rechargeable batteries, such as radios. A prototype has been built that can adapt the outgoing voltage based on the power needs of the device being plugged in.
Intel has also demonstrated an integrated solution that places the SSC technology inside a laptop. Referred to as Alternative Power Architecture (APA), the chipset regulates power going into the machine so that solar panels can plug directly into the power port without the need for an external box. A lightweight 20-watt portable solar panel is enough to power and charge a single 2 in 1 PC (pictured at top).
The current versions of SSC can power the Classmate PC and the Education Content Access Point; and another variant, created by Cellpoint Systems, can power any USB device. Pilot projects using this technology are expected to commence this year.
Source: Intel Free press