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How practical is it to manufacture solar cells on the Moon? I understand there is a lot of silica there, and in theory if we could robotically make and deploy solar cells on the Moon, then we would (in time) have practically unbounded energy to use there.

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    $\begingroup$ The Moon has all the needed elements needed to manufacture solar cells, except money. Silicon wafer manufacture requires a ludicrously large and complex infrastructure to support it, to the extent that many small-to-medium countries on Earth cannot afford to do it themselves. Setting up a sufficient infrastructure to lead to silicon wafer manufacture for solar cells on the Moon will require not millions, nor billions, but trillions of dollars. Many of them, too! $\endgroup$
    – PcMan
    Aug 22 at 9:29
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    $\begingroup$ It looks to me like shipping smallish amounts of Perovskites to the moon and manufacturing solar cells out of that would be a lot cheaper. I don't see money as an issue really - and I doubt it would cost more than a couple of hundred million to put a 3D printer churning out Pervoskite solar cells once the Startship is up and running. But we will see. $\endgroup$
    – Mike Wise
    Aug 22 at 10:07
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Perovskites may prevent the need for such complex manufacturing facilities.

https://www.nasa.gov/feature/glenn/2019/building-solar-panels-in-space-might-be-as-easy-as-clicking-print

Perovskites are made of Calcium, Titanium, and Oxygen, all of which have been found in significant quantities (>1%) on moon rocks (source).

This source estimates the Moon's crust to be composed of 4-6% Calcium, 1-2% Titanium, and a whopping 60% Oxygen. (Silicon is estimated at 16% and Aluminum at 6%, for anyone interested in making mirrors.)

Also needed for Perovskites is an absorber material, usually (so far) either methylammonium lead trihalide or the same thing with tin in place of lead. Sourcing these must be considered as well at some point.

See Perovskite Solar Cells on Wikipedia as well, and this article, which mentions some other details. One drawback: Perovskite cells have had shorter lifespans than other cells. One interesting fact: They have some reliance on lead (Pb), which has made them unattractive for on-Earth applications, but may not matter as much in space.

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  • $\begingroup$ Accepting this to call attention to a key insight. 1 liter of fluid can apparently make a megawatt of solar power. I actually find this hard to believe, but if true... $\endgroup$
    – Mike Wise
    Aug 11 at 7:02
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    $\begingroup$ Another key point is perovskites are challenged heavily by the earth's corrosive atmosphere. The Moon, and even Mars would be much more forgiving. $\endgroup$
    – Mike Wise
    Aug 11 at 7:03
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There are parts that would be easy, and parts that would be quite difficult. Here is a video that shows you how solar cells are made on Earth.

Here's a few things you need:

  1. A very high efficiency clean room.
  2. Wafer manufacturing capabilities
  3. Etching equipment
  4. Diffusing equipment
  5. Metal inlaying

Bottom line is, this is very large and difficult equipment. It would probably not work very well. What are some alternatives? The best alternative would be to make mirrors, which in turn heat a substance, like water, and runs like any turbine engine runs. Wikipedia has a nice photo of one of these on Earth.

enter image description here

Mirrors, especially non-precision mirrors, would be relatively easy to manufacture on the moon. Aluminum and silicon are quite plentiful, the two key elements to making mirrors. The turbines might be difficult to manufacture on the Moon (I really don't know about this one), but they could be brought from Earth, reducing the weight significantly vs the solar panels that would be required to make this system work via direct transport from Earth.

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    $\begingroup$ This is a good start, but doesn't really address how to make them on the moon. That is a different place, and the high volume approaches used on earth under highly competitive conditions with easy access to capital inevitably leads to using large amounts of specialized equipment. I would think manufacturing on the moon would have to use a different approach. $\endgroup$
    – Mike Wise
    Jul 1 '15 at 10:00
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    $\begingroup$ Solar cells would require all of the items listed. The equipment brought to the Moon would be lighter, and probably not as fancy of equipment, but it will still require the same type of stuff. Computer chips, which solar cells are a type of, require very expensive and heavy equipment. I really think the mirror idea will be the first solar power generated on the moon. It doesn't require anything complex to make happen. As you stated, manufacturing on the moon will require a different approach, namely the use of mirrors instead of photovoltaics. $\endgroup$
    – PearsonArtPhoto
    Jul 1 '15 at 10:38
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    $\begingroup$ I would expect a cleanroom in space to be very different from one on Earth. On one hand there is no suspended dust, on the other hand, even the smallest particle will, when ejected, impact ballistically. $\endgroup$
    – gerrit
    Apr 17 '19 at 8:35
  • $\begingroup$ It's worth noting that mirrors can reflect additional light onto solar cells. $\endgroup$
    – ikrase
    Jun 26 '19 at 5:47
  • $\begingroup$ It's not necessarily an either/or choice in the long run. We could do mirrors first to give us more power to work with, and solar cells after that using that increased power output. $\endgroup$
    – DJG
    Aug 10 at 12:32
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Lunar Reources Inc. proposes to manufacture solar panels in situ by electrolyzing the lunar regolith to seperate the various components (metals, silicon, oxygen, etc.) and vacuum-depositing material on the surface. There's an article on Universe Today about their proposal to build a radio telescope of the far-side of the moon using this technique. Universe Today also has a podcast interview with their CTO Alex Ignatiev that goes into more detail regarding the production of solar cells specifically.

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On Earth the factories that make silicon solar cells operate within a greater economy that offers ready access to energy, water, construction capability, specialist suppliers and services. Manufacturers don't exist and work in isolation or self-sufficiently in extreme environments.

Making solar cells on the moon appears to require something very different. It appears to require some kind of highly automated and wholly self contained solar cell manufacturing plant built of modular elements, that has to include associated mining, refining and processing and production of all the materials and consumables that complex and exacting solar cell manufacturing requires.

It appears beyond our current technological capabilities to make such an automated, self contained PV manufacturing plant, even one operating with full access to those specialist materials, consumables and services on Earth.

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  • $\begingroup$ I think the implicit goal is to USE in-situ these PV. The implicit hypothesis seems to be that transport from Earth to the Moon is prohibitive. $\endgroup$
    – Ng Ph
    Aug 11 at 16:39
  • $\begingroup$ @NgPh - well, it IS prohibitive (as well as lacking any commercial viability) but so is in-situ manufacture. I suggest that in-situ is a different kind of prohibitive, requiring advanced technologies that can do and provide what a complex, globally interconnected, low transport cost economy does, without the economy or the economies of scale that help make highly specialised materials and services available and commercially viable. $\endgroup$
    – Ken Fabian
    Aug 12 at 1:17
  • $\begingroup$ Worth considering that certain aspects of the moon may actually make it easier than it is on earth (ex. near-vacuum for atmosphere already) $\endgroup$
    – DJG
    Aug 12 at 11:10
  • $\begingroup$ Maybe the solution is to use nuclear at the beginning to get the production facilities up and running, then gradually switch to solar as more panels have been manufactured. $\endgroup$
    – DJG
    Aug 12 at 11:23
  • $\begingroup$ @DJG - that sounds like establishing supporting infrastructure and services first; a chicken and egg problem? A lot will depend on what the moon mission/project is trying to achieve and doing it within limited budgets. Cost of developing complex technologies for Lunar missions are very high but there are no commercial opportunities. $\endgroup$
    – Ken Fabian
    Aug 12 at 23:14

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