Caltech’s very ambitious solar space project, sponsored by a massive hundreds of millions of dollars in donations, is preparing to launch its first prototypes into orbit. These cutting-edge ultralight structures will collect, convert and wirelessly transmit energy.
It’s very clear Why you want to harvest solar energy in space: 24-hour access to almost unlimited solar energy with no atmosphere in the way, let alone weather or obstructions. The energy potential in space is about eight times better per square meter of solar panel than here on Earth. The problem is always how you do it – and indeed, how much it costs. The costs associated with launching, assembling and maintaining space equipment are astronomical. The scale of a profitable solar space installation is bewildering, and unprecedented problems present many obstacles at every step of the journey.
Undeterred, and motivated by the challenge, a team at Caltech has been working on the Space Solar Power Project for nearly a decade now. It was launched with an extraordinary endowment of more than US $ 100 million from Irvine Company Chairman Donald Bren back in 2013 – a donation that was recently disclosed – and increased to the tune of US $ 17.5 million by Northrop Grumman in 2015.

Steve Babuljak for Caltech
The project continues in three streams. One group is working on lightweight, high-efficiency photovoltaic cells with power-to-weight ratios about 50-100 times greater than the solar panels currently used on the ISS and modern satellites.
The second team focused on developing ultra-lightweight, miniature, inexpensive equipment to convert DC power from solar panels into radio frequency power, then beam it back to Earth, using phase manipulation to electronically transmit the beam to the receiver arrays. the face
These two teams combined their progress into functional prototypes of a “tile” – about 10 cm (3.9 in) square, which combines solar energy capture, conversion to RF and wireless transmission. These highly integrated, highly flexible tiles weigh less than a tenth of an ounce (less than 2.8 g) each, and they are designed to fold into a configuration with essentially zero waste. space, to be placed in a launch vehicle and sent into orbit, where they will unfold themselves.
You can see a prototype tile that harvests light and transmits the energy to a video receiver below.
MayTile demo
Thus, the entire solar array in space is envisioned as an ultra-modular assembly. The tiles are designed to be attached in 2-m-wide (6.6-ft) strips measuring up to 60 m (197 ft) in length. These strips are attached to modules measuring 60 x 60 m (197 x 197 ft).
And so a third group is working on how to make a full-sized array that combines thousands of tiles in modules, and thousands of modules in a large solar harvesting and a transmission array with an area of 9 sq km (3.5 sq miles). This group took on the challenge of creating ultra-lightweight, ultra-thin space structures for these modules that fold very tightly, and then unfold autonomously into larger modules and retain their shape and position as the array moves through space like a flying carpet.
This group has done some amazing work; inspired by Japanese origami and kirigami, they designed and prototyped coiling, folding, self-assembling structures – including coilable joints – weighing only 150 grams per sq m (0.45 oz per sq ft). Some of them can be seen in the video below.
Space Solar Power Project
Then comes the problem of angling its solar panels to the sun as much and as passively as possible, while electronically aiming its transmitters at giant receiver stations on Earth below. And then comes the issue of exactly which orbit to take – a geosynchronous orbit that always points a receiver at Earth below, or a lower, cheaper orbit that requires more solar harvesters and more receivers that bound to the Earth.
The financial math at this stage appears to favor the latter; five solar arrays in a medium Earth orbit, equipped with a double-sided solar harvester and single-sided transmitters appear to have an edge in terms of Levelized Cost of Energy (LCoE) even though such a system would require 39 space launches in contrast. to only 13 for a single-array geosynchronous system – with many assumptions made, of course. But the cost of solar energy in space is still in the range of US$1-2 per kWh – a tough sell because electricity in the US currently sells for less than US$0.17/kWh on average.
The level of difficulty here can best be described as ridiculous. And yet, under the leadership of Caltech Professors Sergio Pellegrino, Harry Atwater and Ali Hajimiri, the Space Solar Power Project team continues to solve the problem. This pioneering work resulted in dozens of published research papers.

Caltech
In December of this year, it will also result in the test of the space-based prototype, a milestone that shows the incredible budget that this group can do. It’s unclear how far the money will go with this project, but even $120 million isn’t likely to make a big dent in the tall stack of spondoolies needed to get a full-size space solar rig that works.
New Zealand company Emrod made the argument to us earlier this month that it would be cheaper to build a terrestrial renewable energy harvesting network, and simply beam the energy around via satellite. But whatever the case, the sheer audacity of the Space Solar Power Project, as well as the fundamental advances it has made in so many different areas, make it a project of great importance.
Enjoy a presentation of this groundbreaking work below.
Space Solar Power: A New Beginning – Sergio Pellegrino – 10/31/2018
Source: Caltech