Solar power seems the most likely renewable energy solution when looking into the future. This conversion of energy turns sunlight into electricity, either directly through photovoltaics (PV), indirectly using concentrated solar power or a combination. But now, Caltech is taking this a step further by collecting solar power in space and sending it to Earth but before we get into Caltech’s Space Solar Power Project (SSPP), let’s take a quick look at what solar power is.

What Is Solar Power?

Solar power technologies convert sunlight into electrical energy which can be used to generate electricity, stored in batteries or thermal storage. Concentrated solar systems use lenses or mirrors and solar tracking systems to focus a large area of sunlight into a small beam.

As mentioned earlier, photovoltaic cells convert light into an electric current using the photovoltaic effect. When the sun shines onto solar panels, energy from sunlight gets absorbed by the PV cells. From there, the energy creates electrical charges that move in response to an internal electric field within the cell. This process causes electricity to flow.

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Caltech Space Solar Power Project (SSPP)

Caltech’s Space-based Solar Power Project started as far back as 2013 when the first donations came from Donald and Brigitte Bren. Donald Bren is the chairman of Irvine Company and on the Caltech board of trustees. He proposed to fund a research project at the university after hearing about the idea of space-based solar in Popular Science. Since then he has donated more than $100 million for the SSPP.

Caltech described it as: “Collecting solar power in space and transmitting the energy wirelessly to Earth through microwaves enables terrestrial power availability unaffected by weather or time of day. Solar power could be continuously available anywhere on earth.”

According to SSPP researcher Harry Atwater: “This ambitious project is a transformative approach to large-scale solar energy harvesting for the Earth that overcomes this intermittency and the need for energy storage.”

Getting Solar Power Straight From Space

The concept emerged from the current limitations of renewable energy. As you may know, solar power is ubiquitous on the surface but it is highly dependent on weather conditions, the season and time of day. With the current technology, no solar panel (on Earth) can work at full capacity all the time, even in perfect conditions. So the obstacle involves transferring and storing energy in a smart grid.

Thanks to this research project, solar panels in orbit are different as they may be exposed to full sunlight nearly all the time. There’s also no reduction in power it generates from sunlight passing through the planet’s protective atmosphere and magnetosphere. All that’s needed now is finding a way to beam that energy to the Earth’s surface without losing too much of it on the way down.

Wireless Transfer Of Solar Power To Earth

SSPP is in the process of launching multifunctional technology-demonstrator prototypes. These involve collecting sunlight, converting it into electrical energy, transferring energy wirelessly through radio frequency (RF) electrical power and deploying ultralight structures to integrate them.

As incredible as this may be resembling something from a Sci-Fi film, the Space Solar Power Project is not without limitations. Researchers are currently still working out how to collect enough energy that makes it viable in the first place. Even with some obvious challenges, this solar power project has tremendous potential and we could see it launch even earlier than anticipated.

They’ve produced several published studies and prototypes including the lightest solar collector-transmitter made by an order of magnitude. It is now on the verge of launching its first space-based test satellite.

Building A Space Power Station

Co-director of the project Ali Hajimiri says the launch is currently expected to be Q1 2023 involving several demonstrators for space verification. The focus is on key technologies involved in the effort, such as:

These are small six feet scale tests but the plan is to develop something much larger than anything currently in space.

“The final system is envisioned to consist of multiple deployable modules in close formation flight and operating in synchronization with one another. Each module is several tens of meters on the side and the system can be built up by adding more modules over time.” (Hajimiri)

Future Ambitions For Space-based Solar Power Systems

The future concept calls for a structure as large as 5-6 kilometres across but it will be far enough from Earth that it won’t be visible to the naked eye. It would send power to receivers on the Earth’s surface using directed, steerable microwave transmission. By putting a few of these in orbit will allow solar power to be beamed to any location on the planet non-stop.

At least that’s the plan but it could be a few years away if it’s deemed probable. Even if it doesn’t work as intended, the pursuit of this idea has produced advances in solar cells, flexible space-based structures and wireless power transfer.

Final Thoughts

It might seem like a pipedream and far-fetched but how many inventions and engineering feats have been just as ambitious? Renewable energy and solar power, in particular, will play a massive role in the future so why not get ahead of it?

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