Arizona-based Solestial’s silicon-based solar cells are highly durable in space, according to third-party testing.
France’s Alternative Energies and Atomic Energy Commission (CEA) has confirmed that Solestial’s solar cells can repair radiation-related damage. Its tests have confirmed that silicon cells effectively anneal radiation damage in sunlight at 194 F (90 C). Annealing is a process of slow cooling to remove internal stresses in the material.
The open-circuit voltage of Solestial’s silicon solar cells dropped only 4% and retained 96% of its original value after being exposed to radiation equivalent to 10 years in low Earth orbit and annealing at 194 F under one solar illuminance equivalent. The company said its 20-micron-thick cells show more than 20 percent efficiency.
The company said the tests demonstrate the feasibility of self-curing solar cells that greatly reduce degradation from radiation. This is especially important for solar cells located in space, which are exposed to high levels of radiation and are required to function for a long life cycle.
“Annealing radiation damage in silicon is straightforward at high temperatures, say above 200-250 C, but this is not useful for space applications, as these temperatures are rarely, if ever, experienced in situ,” said Romain Cariou. CEA Space Silicon Solar Energy Applications Specialist. “The differentiator here is that Solestial’s cells can heal radiation damage at the normal operating temperatures of solar panels in space.”
Cariou said this response to irradiation is not found in current commercial cell technologies. During the 10-year mission, the commonly used III-V solar panels lose 10–15% of their life cycle from the beginning due to radiation damage alone. The damage of traditional terrestrial silicon solar panels is even higher, 35-40%. Neither III-V nor terrestrial silicon has shown independent laboratory validation for such significant low-temperature annealing, said Solestial.
“We look forward to further testing with CEA in the coming months to confirm our internal annealing results at even lower temperatures,” said Stanislau Herasimenka, CEO of Solestial. “We are excited to show the space industry the myriad benefits of Solestial’s ultra-thin silicon solar cells and coatings.”
The company said another advantage of its technology is that it is silicon-based, while many other space-made solar panels are often made of rarer or more expensive materials, such as gallium arsenide. The Arizona-based company has been developing its technology for over a decade, starting at Arizona State University. It went through a $10 million seed funding round in October 2022.