April 27, 2023

It’s always sunny in outer space. Could that be a source of energy on earth? 

Space-based solar arrays are a staple of science fiction –  an idea that has ignited the imaginations of technologists and researchers for several decades. They involve vast arrays of orbiting solar panels that collect energy and beam it wirelessly to where it is needed. 

Beyond sci-fi though, there are very real efforts to make space-based solar power (SBSP) a reality.

“There are very aggressive research programs related to this technology in several countries such as the United States, China, Japan, Russia, South Korea and India,” said Raul Colcher, IEEE Life Senior Member.

A bright future? 

The CalTech Space Solar Power Project (SSPP) launched in early 2023 with a package of prototype components that could be used in orbital solar farms. China has plans for a station with commercial generation capacity as early as the 2030s.

The U.S. conducted research into orbital solar through the ‘70s when energy prices were high, but largely abandoned work on the issue in the early 2000s, because of a mix of financial and technical challenges. Two trends have renewed interest. The first is the drive toward net zero carbon emissions by 2050. Second is the distant possibility of a lunar base. SBSP could provide a source of power for vehicles and structures on a lunar base, especially in its critical early days. 

Proponents say it has a couple of advantages, although implementation may still be decades away. If it ever comes to fruition, it could make solar power available at night or when it is cloudy, something that ground-based solar can’t do. About 30 percent of solar radiation never makes it to ground level. And then there’s the sheer scale of solar power: sunlight in space is abundant on scales that dwarf earth-based power sources.

“In space the sun is always shining, the tilt of the Earth doesn’t prevent the collection of power and there’s no atmosphere to reduce the intensity of the sun’s rays,” said IEEE Senior Member Inderpreet Kaur. “This makes putting solar panels into space a tempting possibility.”

Will they ever get off the ground? 

Detractors point out the massive number of technological hurdles that must be overcome before such a project reaches feasibility: how to assemble solar arrays in space, how to transmit energy back to earth and how to launch materials into orbit in a cost-effective and energy-efficient manner. 

“The idea for space-based solar arrays has been around for many years but the technical challenges are still there,” said IEEE Fellow Panagiotis Tsiotras. “I do not believe the economics work at the moment in terms of power efficiency, or the manufacturing and assembling of such large solar arrays. To make progress, advances in those areas are needed, as well as in materials.”

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Igniting the Imagination

Still, prototypes are on the way and drawing lots of attention. One of CalTech’s experiments, called the Deployable on-Orbit ultraLight Composite Experiment (DOLCE), looks at the modular components of a self assembling solar array. 

To beam the power back to earth, researchers focus on converting sunlight into one of two other forms: lasers or microwaves. Most microwave designs envision the transmission of massive amounts of power, requiring receivers on the ground that are several kilometers. Laser technology allows for smaller, more focused applications on the order of one to 10 megawatts. But that would require many, many more satellites than a microwave-based system. A laser-based system might be useful for remote locations on Earth with high power demands, such as in mining operations, for example.

Depending on who you ask, the idea of space-based solar power is either just around the corner, or an expensive boondoggle. But it’s an idea that has captivated technologists across the globe. And research into this project could have unexpected results decades from now.

“Space-based solar is possible,” said 2023 IEEE President-Elect and IEEE Life Fellow Thomas Coughlin. “I am sure that space-based solar arrays will be used to power the development of industry and resource development in outer space – and in that way it will be a benefit for people living on earth.”


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