Solar cells for space are typically grown on slices of germanium metal. An ESA General Support Technology Programme (GSTP) project looked into being able to remove and recycle this rare, expensive metal, resulting in much thinner and cheaper solar cells for missions.
The activity tested a method where the surface of the Germanium substrate is treated so that a cavity is introduced just below it. Once a solar cell is grown on the Ge surface, this 0.001 mm thick gap, or cavity, allows everything above it to be removed, leaving just a very thin layer of germanium still attached to the cell – around 10 micrometres thick instead of the previous 150.
This huge saving of weight and volume of a rare material will result in major cost savings, especially when multiplied across the roughly 10 000 solar cells needed for each satellite mission.
For more than a quarter of a century ESA’s optional GSTP has been preparing promising technologies for space and the open market. Read our GSTP Annual Report for 2019 to learn more about programme activities.