There are plenty of different solar technologies out there claiming to be superior, but innovation continues to bring more surprises. I’ve got a piece at Technology Review today about research going on at McMaster University in Hamilton, Ontario, that could result in more efficient, cheaper and flexible solar cells composed of hair-like nanowires.

The nanowires — about 1,000 times thinner than a human hair — are literally grown on a substrate, whether it be silicon, metal foil, carbon-nanotube fabric or just glass. Some labs have grown the nanowires out of silicon, but the McMaster group has chosen Group III-V materials — such as gallium and arsenide — that are capable of absorbing much more energy from the sun than silicon. While the materials are expensive, they’re better — that’s why they’re used in solar panels for space-based applications. When used in nanowires, however, so little material is needed that it becomes affordable.

The McMaster lab basically seeds a substrate with nanoparticles of gold or aluminum and then exposes the particles to gases of gallium and arsenide. The nanowires grow upward from there, like a dense grass or a thick growth of stubble, as the gas crystalizes into a solid. It’s a very cool process. The challenge is to get a dense, high-quality and pure turf of nanowires to maximize efficiency. In principle, nanowires are better at light conversion because their length allows more absorption of energy when the sunlight hits their tips. But they’re thin enough to allow the excited electrons to escape, making it easy to collect the electrons and produce electricity.

McMaster has partnered with Cleanfield Energy, a developer of renewable technologies, and the Ontario government. Cleanfield and the Ontario Centres of Excellence have contributed about $600,000 to a three-year initiative that’s aiming to develop affordable nanowire solar cells with 20 per cent efficiency. Definitely a project I’ll be following over the coming years.

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