Power up with solar cells
A new crop of solar cells might well change the way we produce energy.
IMAGINE a backpack that charges the laptop inside as you run between meeting rooms, a briefcase that powers your mobile phone, plastic curtains that power your computer, or an umbrella that powers a radio or a fan while you laze on the beach.
These applications, which allow people to produce solar energy wherever they are, are now possible with the new generation of organic photovoltaic technology which features solar cells that are light and flexible. Unlike rigid, bulky and heavy crystalline silicon-based solar cells (referred to as first generation solar technology), these cells are just thin sheets of plastic printed with photovoltaic material. Made by Konarka Technologies in the United States, they are aptly called Power Plastic.
“Their low weight and flexibility give organic photovoltaic cells an edge over existing silicon-based ones, enabling them to be used in numerous applications, from microelectronics to portable power, remote power and building-integrated applications,” says Kong Chock Heng, managing director of L2E Solar, the Malaysian distributor of Power Plastics.
At the heart of Power Plastic’s technology is a photo-reactive polymer material invented by Konarka co-founder Dr Alan Heeger, who won the Nobel Prize in chemistry in 2000 for the discovery and development of conductive polymer. This carbonbased (hence the word “organic” in the name) photovoltaic material captures both indoor and outdoor light and converts it into direct current electrical energy which can be used immediately, stored for later use, or converted to other forms.
Power Plastic comprises several thin layers: a photo-reactive printed layer, a transparent electrode layer, a plastic substrate and a protective packaging layer.
“The conductive polymer can be printed or coated onto flexible substrates using roll-to-roll manufacturing, similar to the way newspaper is printed on large rolls of paper. This simplifies the manufacturing process, thus lowering costs. And because it is conducted at low temperatures, it is less energy intensive than first or second generation photovoltaic technologies,” says Kong.
The production also incurs lower environment impact as it is made of carbon-based polymer which is more environment-friendly than the photo-active materials (such as amorphous silicon, copper indium gallium diselenide or cadmium telluride) used on thin-film solar cells (second generation solar technology).
Usage of the organic solar cells, however, is currently limited by its efficiency – at 3%, it is way below the 12% to 20% of silicon and thinfilm solar cells. Research is ongoing to improve the product. Another setback is that prices remain high – it costs twice as much as silicon cells – as the product was commercialised only last year. But Kong believes that the characteristics of the organic solar cells give them an edge in numerous applications, particularly as portable and remote power sources. “You get the power where you are,” he says.
He is working with manufacturers to incorporate Power Plastics into bags, backpacks, umbrellas, outdoor banners, roofs and canopies, in essence turning these goods into energy-producing devices.
Portable power: Kong Chock Heng, managing director of L2E Solar, totes a bag that has a solar cell attached to its front flap, turning it into a
portable battery charger.