Tiny 'snowflake' cells to revolutionise solar

SOLAR ENERGY CELL DEVELOPMENT:US GOVERNMENT scientists have developed tiny glitter-sized solar photovoltaic cells shaped like snowflakes that could revolutionise solar energy.

Fabricated using microelectronic and microelectromechanical systems (MEMS) techniques common to today’s electronic foundries, the solar particles, made of crystalline silicon, hold the potential for a variety of new applications because of their unique size.

They have been developed by scientists at Sandia National Laboratories, which undertakes RD into nuclear weapons, energy and defence technologies.

At 14 to 20 micrometers thick (a human hair is around 70 micrometers thick), these six-inch-squared solar panels are 10 times thinner than conventional ones, yet perform at about the same efficiency.

Sandia lead investigator Greg Nielson said the research team has identified more than 20 benefits of scale for its microphotovoltaic cells. These include new applications, improved performance, potential for reduced costs and higher efficiencies.

“Photovoltaic modules made from these microsized cells for the rooftops of homes and warehouses could have intelligent controls, inverters and even storage built in at the chip level. Such an integrated module could greatly simplify the cumbersome design, bid, permit and grid integration process that our solar technical assistance teams see in the field all the time with conventional solar panels,” said Sandia field engineer Vipin Gupta.

“Snowflake-shaped solar cells use 100 times less silicon to generate the same amount of electricity,” said researcher Murat Okandan. “Since they are much smaller and have fewer mechanical deformations for a given environment . . . they may also be more reliable.”

The cells can be fabricated from commercial wafers of any size, including today’s 300mm (12in) diameter wafers and future 450mm (18in) wafers.

They use less wiring than larger panels, which helps to make them more cost effective and easier to make. And if one cell proves defective once it has been manufactured, the rest can still be harvested.

“The shade tolerance of our units to overhead obstructions is better than conventional PV panels,” said Nielson, “because portions of our units not in shade will keep sending out electricity where a partially shaded conventional panel may turn off entirely.”

The cells being developed at Sandia are about 15 per cent efficient at generating electricity. This compares to about 13 to 20 per cent in off-the-shelf conventional solar panels.