Now, a groundbreaking innovation may change that: researchers have developed a method to fully recycle modern solar panels using water as the main solvent, which would make it a truly sustainable energy.

The method from scientists at Linköping University in Sweden can recycle all parts of a modern solar cell repeatedly without environmentally hazardous solvents—and the recycled solar cell has the same efficiency as the original one.

The method works with one of the most promising technologies for next-generation solar cells: perovskite.

Perovskite solar cells are not only relatively inexpensive and easy to manufacture but also lightweight, flexible, and transparent. Thanks to these properties, they can be placed on many different surfaces, like windows. Also, they can convert up to 25 percent of the solar energy into electricity—comparable to today's silicon solar cells.

However, silicon panels are at the end of their life cycle, which has created a landfill problem.

"There is currently no efficient technology to deal with the waste of silicon panels. That's why old solar panels end up in the landfill," says Xun Xiao, in the Department of Physics, Chemistry and Biology at Linköping University.

"We need to take recycling into consideration when developing emerging solar cell technologies," said Feng Gao, a professor of optoelectronics at the same Swedish college.

"There are many companies that want to get perovskite solar cells on the market right now, but we'd like to avoid another landfill," adds Niansheng Xu, postdoc at LiU. "In this project, we've developed a method where all parts can be reused in a new perovskite solar cell without compromising performance in the new one."

Given that perovskite solar cells currently have a shorter life span than silicon solar cells, it is important that perovskite solar cell recycling is efficient and environmentally friendly. They also contain a small amount of lead, necessary for high efficiency, so this also must be addressed in a functioning recycling process.