Cloudy, gloomy days can be a drag on solar panels. But not if the panels are in space. Satellites that orbit thousands of kilometers above earth receive more intense sunlight 24 hours a day, and generate power continually. For years, scientists have been toying with the idea of collecting solar energy in space and beaming it down to earth wirelessly.
Now, a study shows that space-based solar farms could become commercially viable. For the study, researchers in the UK monitored the performance of a new kind of low-cost lightweight solar panel installed on a satellite for a period of over six years, which entailed 30,000 orbits. The panels’ performance exceeded the team’s expectations, they report in the journal Acta Astronautica.
Several efforts towards making space-based solar farms a reality are now underway around the world. In June, a Caltech team successfully demonstrated a small prototype system that collected sunlight, turned in into electricity, and sent it back to earth. The Japanese space agency plans to beam solar power from space by 2025, and the European Space Agency last October revealed plans for a solar farm that would orbit 36,000 km above earth.
While the idea of space solar farms has been around for a long time, it faces many technical and logistical challenges. One is that sending payloads into space is very expensive.
To be practical and affordable, any massive solar power system deployed in space will need to use solar cells that are lighter and produce more power-per-weight than conventional solar cell technologies, the team from the Universities of Surrey and Swansea in the UK write in the new paper.
As a solution, they developed solar cells made from a material called cadmium telluride. Compared to conventional panels made of silicon, cadmium telluride solar cells are thinner, lighter, can be made on larger areas, and are more efficient. They can also be relatively cheap to manufacture.
To see if such thin-film cadmium telluride solar panels would last in space, the researchers put them on a satellite developed at the Surrey Space Center. The satellite also carried into space instruments that would measure solar cell performance in orbit.
While the cells’ power output slowly became less efficient, they ended up working for over six years, even though the mission was designed to last for one year. “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,” said Craig Underwood, a professor of spacecraft engineering at the University of Surrey in a press release. “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.”
Source: Craig Underwood et al. IAC-22-C3.3.8 Six years of spaceflight results from the AlSat-1N Thin-Film Solar Cell (TFSC) experiment. Acta Astronautica, 2023.
Image: European Space Agency
