As a renewable source of energy, solar power has become a trend. Unlike fossil fuels like coal, solar power is clean and emissions-free. While it is good for the environment, it has some drawbacks. It is not entirely cost-efficient, and we need better ways of recycling it.

But now we’re learning that researchers in Sydney may have found a way to tackle this issue.

A solar panel consists of a layer of silicon cells. Silicon, acting as a conductor and an insulator for solar panels, is the second most abundant material found on the planet after oxygen. The silicon found in solar panels is highly processed and goes through annealing. This heat treatment process is used to increase the flexibility of a material and reduce its hardness. 

Time-saving and energy efficient

Currently, annealing is done in a furnace with a high temperature ranging between 1652 and 2012 °F (900 and 1100 °C). In a paper published recently, a team has shown that heating silicon solar cells using microwave radiation is nearly as efficient as using a furnace. However, the former is time-saving and energy efficient, over many other advantages. 

In a statement released by Macquarie University, the researchers explain that microwave radiation selectively heats silicon and leaves the laminated panel of glass, aluminium, and plastic largely unaffected. This has a significant recycling benefit.

Under treatment, the plastic coating, which protects the silicon plate from contamination and moisture, gets softened and hence can be peeled off mechanically. The scale can be then easily delaminated, and its components can be reused without harsh chemicals. 

“Until now, it made economic sense just to dump the panels in the landfill,” said Dr Binesh Puthen Veettil, study lead and senior lecturer of the School of Engineering at Macquarie University.

“In the rare instances when they are recycled, you crush the panels, heat them to about 1400°C, and wash them with chemicals to remove the plastic – a highly energy-demanding process. But now, as the solar panels which began to be installed in vast numbers about 20-30 years ago are reaching the end of their life and being decommissioned, governments are demanding they be recycled.”

Microwave heating is an economically viable, fast, and energy-saving option used extensively in the rubber, wood, and ceramic industries.