Solar might be more efficient than nuclear energy to supply power for a six-person extended mission to Mars that will involve a 480-day stay on the planet’s surface before returning to Earth, according to new US research.

Researchers at the University of California, Berkeley, have compared how PV or nuclear energy could power a crewed outpost for an extended period on Mars and have determined that solar offers the best performance.

“Photovoltaic energy generation coupled to certain energy storage configurations in molecular hydrogen outperforms nuclear fusion reactors over 50% of the planet’s surface, mainly within those regions around the equatorial band, which is in fairly sharp contrast to what has been proposed over and over again in the literature, which is that it will be nuclear power,” said UC Berkeley researcher Aaron Berliner, noting that two energy sources were compared for the power supply of a six-person extended mission to Mars involving a 480-day stay on the planet’s surface before returning to Earth.

The US team considered four different scenarios: nuclear power generation with the miniaturized nuclear fission Kilopower system, PV power generation with battery energy storage, PV power generation with compressed hydrogen energy storage produced via electrolysis, and hydrogen generation with compressed hydrogen energy storage (PEC).

“In our calculations, we assumed a capacity factor of 75% to account for the solar flux deviation throughout the Martian year and sized energy storage systems to enable 1 full day of operations from reserve power,” the group explained. “We then calculated the carry-along mass requirements for each of the power generation systems considered.”

The scientists found that, of the three PV-based power generation options, only the photovoltaics-plus-electrolyzer system outcompetes the nuclear system based on carry-along mass. They also said that the optimal absorber bandgaps for the PV systems depend heavily on the location on the surface of Mars, the total depth of the air column above a given location, gradients in dust and ice concentrations, and orbital geometry effects that cause different effective air column thicknesses for locations near the poles.

“In conclusion, solar cell arrays with careful attention to semiconductor choice and device construction represent a promising technology for sustaining an Earth-independent crewed habitat on Mars,” the academics said. “Our analysis provides design rules for solar cells on the Martian surface and shows that solar cells can offer substantial reduction in carry-along mass requirements compared to alternative technology over a large fraction of the planet’s surface.”

They explained their findings in “Photovoltaics-Driven Power Production Can Support Human Exploration on Mars,” which was recently published in Frontiers.