Although solar cells are good for the environment, they also have drawbacks. They are expensive to make and there are limited ways to recycle them. However, researchers have developed a new manufacturing technique that can address both of these issues.
It is well known that solar power is good for the environment. With no direct greenhouse gas emissions, sunlight is a renewable resource that won’t run out anytime soon.
Solar panels are made up of solar cells and convert light energy from the sun or artificial light directly into electricity through the photovoltaic effect. However, the drawback of manufacturing solar panels is that the production of solar cells is very energy intensive and there are limited ways to recycle solar cells at the end of their life.
Now researchers may have a solution. A team from Macquarie University in Australia has developed an improved and time-saving solar cell manufacturing process with the added benefit of facilitating recycling.
Silicon is the most common semiconductor material used in solar cells. To manufacture solar panels, silicon undergoes a heat treatment process called annealing. This changes the physical properties and performance. Annealing is currently done in a furnace and requires temperatures between 1652 and 2012 °F (900 and 1100 °C).
Researchers have found that using microwave radiation to heat silicon is almost as efficient as using a furnace. Microwave heating is already used in the rubber, ceramics, and wood industries due to its energy efficiency, speed and uniformity of heating, and economic viability.
Microwave radiation selectively heats silicon, speeding up the annealing process and making it significantly more energy efficient. Furthermore, it can be used to selectively heat sections of solar panels by focusing microwaves, making it suitable for annealing new solar panels employing heterojunction technology interwoven with crystalline and amorphous silicon.
Microwave annealing is also clean, unlike furnaces where chemicals build up during the heating process.
“That means less contamination,” said Binesh Veettil, lead author of the study. “And the whole process can be done at room temperature.”
Through experiments with microwave annealing, researchers discovered additional benefits. The microwave softens the plastic coating that protects the silicon plates from moisture and contamination. This means that the coating can be stripped off and the plate components reused.
“In the past, it made economic sense to simply dump the panels in a landfill,” says Veettil. “In the rare case of recycling, we crush the panels and heat them to about 1,400 °C. [2,552 °F] Clean with chemicals to remove plastic. This is a very energy-intensive process. ”
Researchers plan to conduct further research to optimize the production process.
The study was published in a journal applied physics letter.
Source: Macquarie University
