Ultralight solar cells from MIT

[MajorBringdown]

http://news.mit.edu/2016/ultrathin-flexible-solar-cells-0226

An interesting development at MIT with some really light solar cells, capable of producing 6 watts of power per gram (not kilogram, just regular old gram).

[BrightLight]

Now to get the quantum efficiency to 30%.

[Til800?CU]

and we're off

[Robotbeat]

http://news.mit.edu/2016/ultrathin-flexible-solar-cells-0226

An interesting development at MIT with some really light solar cells, capable of producing 6 watts of power per gram (not kilogram, just regular old gram).

Right. If you can achieve typical 30% efficiencies, you could get extremely fast trips to Mars, accelerating most of the way at about the same as Ceres' gravity.

[alexterrell]

http://news.mit.edu/2016/ultrathin-flexible-solar-cells-0226

An interesting development at MIT with some really light solar cells, capable of producing 6 watts of power per gram (not kilogram, just regular old gram).

Impressive. I wonder what the support and conducting structures have to weigh though.

For the 1MW array, 100m x 100m, this weighs 160kg. Would this need to be point onto aluminium foil weighing 500kg? Then there's the mast to keep it rigid and steer it, and then the cabling - can the aluminium backing be used as a conductor?

Adding it all up, and we might be looking at 2 tons for the 1MW, 100mx100m mast. This DC power at a few hundred volts, which might need to be stepped up.

I remember reading the original proposal for Space Solar Power showed 5GW panels with a mass of 50,000 tons. The above is 5 times lighter.

[Robotbeat]

Don't need it on an aluminum backing!

Build it like a solar sail. Try a spin-stabilized structure or with gossamer supports, with very high voltage power lines to keep the mass down. Design the electric thrusters to take the voltage supplied directly by the solar array so you can get rid of the PPU and just use some relays to control it. The thrusters would have to operate at very high temperatures so that they wouldn't need a heavy radiator.

[Ludus]

Sounds like a great candidate tech for space manufacturing. Good vacuum and microgravity in any volume needed ought to help a lot if it's made using vapor deposition.

[Elmar Moelzer]

You would still need a lot of wiring (which I am sure is not included in that weight) and potentially also some cooling, no?

[TrevorMonty]

You would still need a lot of wiring (which I am sure is not included in that weight) and potentially also some cooling, no?

The conductors add significant weight, increasing voltage to kVs is not simple in a vacuum. Never found a good explain but it seems vacuum provides less electrical insulation than air.

One option is use conductors inside gas or liquid filled pipe. This does offer possibility of using very fine superconductors as gas or liquid could provide low temperatures required. Complex yes but this small pipe could carry considerably more power than equivalent (weight) aluminum conductor.

[Robotbeat]

You would still need a lot of wiring (which I am sure is not included in that weight) and potentially also some cooling, no?

The conductors add significant weight, increasing voltage to kVs is not simple in a vacuum. Never found a good explain but it seems vacuum provides less electrical insulation than air.

That is not true. You can increase to higher voltage. Vacuum is a much better insulator than air. One of the main reason folks don't do it is because of the need for stepping-down the voltage (but some applications, like electric thrusters, can use high voltages directly).

Very high voltages have simply not been required given current arrays. Easier to operate at lower voltage if you don't need higher voltages.

[Eric Hedman]

Don't need it on an aluminum backing!

Build it like a solar sail. Try a spin-stabilized structure or with gossamer supports, with very high voltage power lines to keep the mass down. Design the electric thrusters to take the voltage supplied directly by the solar array so you can get rid of the PPU and just use some relays to control it. The thrusters would have to operate at very high temperatures so that they wouldn't need a heavy radiator.

Without a backing, would something this thin and fragile be able to survive the vibrations of launch?  Has anything this thin been successfully deployed in space? 

I'd also be interested in how this material holds up under the intense sunlight over time.  Sounds like there are plenty of things to test out with this material.

[Robotbeat]

Don't need it on an aluminum backing!

Build it like a solar sail. Try a spin-stabilized structure or with gossamer supports, with very high voltage power lines to keep the mass down. Design the electric thrusters to take the voltage supplied directly by the solar array so you can get rid of the PPU and just use some relays to control it. The thrusters would have to operate at very high temperatures so that they wouldn't need a heavy radiator.

Without a backing, would something this thin and fragile be able to survive the vibrations of launch?  Has anything this thin been successfully deployed in space? 

I'd also be interested in how this material holds up under the intense sunlight over time.  Sounds like there are plenty of things to test out with this material.

No doubt you would start with the material either in a roll (like Hubble's first array or the ROSA array) or z-folded. It would be compact and well-constrained for launch.

[Vultur]

Don't need it on an aluminum backing!

Build it like a solar sail. Try a spin-stabilized structure or with gossamer supports, with very high voltage power lines to keep the mass down.

Has anybody reevaluated space-based solar power with this kind of construction & modern very thin film solar cells?

[Eric Hedman]

Don't need it on an aluminum backing!

Build it like a solar sail. Try a spin-stabilized structure or with gossamer supports, with very high voltage power lines to keep the mass down.

Has anybody reevaluated space-based solar power with this kind of construction & modern very thin film solar cells?

This is so new from MIT that I doubt anyone has done any full blown analysis of how this could change the mass numbers, flights required, etc.  I suspect that more details will need to be worked out before any realistic numbers could be calculated.

[Robotbeat]

There's this article presented at the International Astronautical Congress:

http://www.spacefuture.com/archive/early_commercial_demonstration_of_space_solar_power_using_ultra_lightweight_arrays.shtml

BTW, there's something you should know that you wouldn't know if you just read some press release: Ideas like this are old. In this field of aerospace, just about anything you can imagine has been thought of before, often over half a century ago. MIT may have just developed this solar cell, but people have been thinking about this sort of thing since forever.

[Vultur]

This is so new from MIT that I doubt anyone has done any full blown analysis of how this could change the mass numbers, flights required, etc.

Sure, but thin films in general have been around a while. I believe the cells on IKAROS (launched in 2010) were 25 micrometers thick, and they were on a solar sail, rather like what Robotbeat was describing in terms of deployment.

There's this article presented at the International Astronautical Congress:

http://www.spacefuture.com/archive/early_commercial_demonstration_of_space_solar_power_using_ultra_lightweight_arrays.shtml

Thanks!

EDIT: fixed quote tag

[virnin]

What about lunar implementations rather than free-flying platforms?  Are any of the backing films strong enough to be laid directly on the lunar surface?  I'd be very happy to have a km^2 solar array to support my lunar hotel, preferably several, widely distributed, so at least one of the set would be in sunlight at any given time of the lunar cycle.

[savuporo]

What about lunar implementations rather than free-flying platforms?  Are any of the backing films strong enough to be laid directly on the lunar surface?  I'd be very happy to have a km^2 solar array to support my lunar hotel, preferably several, widely distributed, so at least one of the set would be in sunlight at any given time of the lunar cycle.

Not a new idea. http://www.cam.uh.edu/projects/space-materials - scroll down to 'Solar Cells on the Moon'
CAM used to be called 'Space Vacuum Epitaxy Center' and they published a bunch of research about this about 15-10 years ago.