Satellite mission shows viability of space-based solar farms

The first study of its kind from the Universities of Surrey and Swansea followed a satellite over six years, observing how the panels generated power and weathered the rigours of space after over 30,000 orbits. 

The findings, detailed in Acta Astronautica, could pave the way for commercially viable solar farms in space.

In a statement, Professor Craig Underwood, Emeritus Professor of Spacecraft Engineering at the Surrey Space Centre at Surrey University, said: “This ultra-low mass solar cell technology could lead to large, low-cost solar power stations deployed in space, bringing clean energy back to Earth – and now we have the first evidence that the technology works reliably in orbit." 

According to the team’s paper, space based solar power (SBSP) stations will require large area, lightweight, solar photovoltaic arrays that will provide far greater power than is currently available.

The team said that these arrays will need to use solar cells which have a much higher specific power and lower cost per watt than current space-rated solar PV technologies.

The solution from Swansea University’s Centre for Solar Energy Research (CSER) is a new solar cell technology based on thin-film cadmium telluride (CdTe), deposited directly onto ultra-thin space-qualified cover glass material.

This offers a potentially high specific power and, when adopting the conventional CdTe manufacturing process, a low-cost technology.

Four prototype cells were flown as part of the Thin-Film Solar Cell experimental payload, developed by CSER and the Surrey Space Centre (SSC), on the joint Algerian Space Agency – UK Space Agency AlSAT-1N Technology Demonstration CubeSat that launched into a sun synchronous orbit in 2016.

Dr Dan Lamb from Swansea University: “Large area solar arrays for space applications are a rapidly expanding market and demonstrations such as this help to build on the UK’s world class reputations for space technology.”

The cells showed no signs of cell delamination during the mission, but the team did find that the fill factor for all four cells decreased, which was caused primarily by a decrease in their shunt resistance. This has been attributed to the diffusion of gold atoms from the back electrical contacts, but further development with more stable back contacting methodologies could overcome this.

Professor Underwood said: “We are very pleased that a mission designed to last one year is still working after six. These detailed data show the panels have resisted radiation and their thin-film structure has not deteriorated in the harsh thermal and vacuum conditions of space.”