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THURSDAY 26 MARCH, 2009 |

Recycled Silicon For Solar Cells

by Energy Matters

While a solar panel has a life spanning decades and many panels produced in the 1970's are still operational today, at some stage they will need replacing which means waste that needs to be dealt with.

A traditional monocrystalline or polycrystalline solar panel has very little in non-recyclable materials. The aluminium frames that make up the bulk of a panel can be easily reclaimed; but dealing with the silicon solar cells themselves has posed some challenges; particularly for reuse in their original capacity.

Silicon has dropped in price substantially in recent years, but prime silicon needed for solar panels still remains the most costly component of a module. According to SEMI, a photovoltaic industry association, some manufacturers use wafers made from reclaimed silicon to optimise and monitor their manufacturing processes. After testing, reclaimed silicon wafers are then ground and polished and returned, with the cycle repeating until the reclaimed wafer is no longer useable. Flawed wafers are also sometimes sold to manufacturers of smaller solar powered devices that can utilise lower quality cells.

A new process developed by researchers at Swansea University's School of Engineering will give new life to old silicon solar cells and flawed wafers. The researchers have developed a solar cell made from reclaimed silicon suitable for use in large solar panels. The researchers claim the technology could enable people to buy much lower cost, but still highly efficient solar modules for their homes. Far from being a lower quality product, their first prototype cell achieved a very respectable conversion efficiency of 14%, but the team is aiming to get closer to 20% with their next attempt – 5% better than most current commercial cells.

The team is also developing unique thin film technology which reduces the amount of silicon used in the solar cells. which will cut the costs of production even further.