Methane fuel physical plant details

[JohnDelvfar]

I am very interested in finding out more details of the Mars physical generation plant that will make the Methane fuel' for the return journey.

How Efficient is the sabatier process? will it take years to generate the amount of fuel necessary for a return journey? what are the power requirements of the process? Will you need acres of solar panels or just a few square feet. What amounts of regolith are necessary to produce the required amount of Fuel?  volume of water/cubic meter?  Does anyone know who (what company) is working on this hardware? are there already working prototypes? I know that the ISS has one working now but it is small not the size necessary to produce the fuel for a return from mars mission .

I have been following the discussion about mars missions for years and i have not seen any answers to these questions. I hope someone out there can point me in the correct direction!  thanks

Edited January 23, 2018 by JohnDelvfar
clarity and miss spelling

[PB666]

2 hours ago, JohnDelvfar said:

I am very interested in finding out more details of the Mars physical generation plant that will make the Methane fuel' for the return journey.

How Efficient is the sabatier process? will it take years to generate the amount of fuel necessary for a return journey? what are the power requirements of the process? Will you need acres of solar panels or just a few square feet. What amounts of regolith are necessary to produce the required amount of Fuel?  volume of water/cubic meter?  Does anyone know who (what company) is working on this hardware? are there already working prototypes? I know that the ISS has one working now but it is small not the size necessary to produce the fuel for a return from mars mission .

I have been following the discussion about mars missions for years and i have not seen any answers to these questions. I hope someone out there can point me in the correct direction!  thanks

I think that you should consider what space X says its going to do for getting to Mars and back are only placeholder recipes. IOW they are grossly stating what they know they have to do to get there and back and are adding plausible details that in actuality will be settled on later.

CO₂ + 4H₂ → CH₄ + 2H₂O is the process.
The component CO2 is available in the atmosphere of Mars is 600 pascals with a composition of 98.7% CO2. Its hard to translate this into earths atmosphere but if we use 44.64 moles per cubic meter. And CO2 is 44 moles per cubic meter then a cubic meter of Martian atmosphere would weigh 1.914 kilograms. However since the Martian atmosphere is much thinner 600/101,300 then they would be ~ 11.33 grams per cubic meter. Note that it is the oxygen that drives chemical energy from rockets, so that the oxygen derived from CO2 that is more important than the Methane, I am not sure how rich Methane/O2 rockets are Kerosine runs rich and Hydrolox rockets a bit leaner, so that there is probably not a full burn to CO2 maybe half CO and CO2 in the output. The reason I say this is that to make methane on Mars will require water.

4H20 ---- >1.3V -----> 2H₂ + O₂  Chemical Electrolysis. This is a terribly energy inefficient reaction and is very slow.
Here are the production methods for hydrogen [https://en.wikipedia.org/wiki/Hydrogen#Production].

For each CO2 you turn to methane you will need 2H20 to be converted to Oxygen and hydrogen . . .you will need to store the oxygen as well as the methane, there is no condition on Mars were liquid oxygen and methane are stable as liquids so they will have to be cooled and pressurized.

The question of feasibility of Methane production is a choice with no alternatives, if they want to be able to return from Mars without have a devoted station in LMO, then they have to produce fuel on Mars. That does not mean that they can produce enough fuel to get back to Earth, but assuming that they bring or deposite enough equipment on Mars then it is plausible, if and only if they can find a source of water, there are low spots on Mars that would make getting the CO2 rather easy, up to 2 kPa of CO2, but getting the water would not be east at all.

 

[sh1pman]

59 minutes ago, PB666 said:

I think that you should consider what space X says its going to do for getting to Mars and back are only placeholder recipes. IOW they are grossly stating what they know they have to do to get there and back and are adding plausible details that in actuality will be settled on later.

CO₂ + 4H₂ → CH₄ + 2H₂O is the process.
The component CO2 is available in the atmosphere of Mars is 600 pascals with a composition of 98.7% CO2. Its hard to translate this into earths atmosphere but if we use 44.64 moles per cubic meter. And CO2 is 44 moles per cubic meter then a cubic meter of Martian atmosphere would weigh 1.914 kilograms. However since the Martian atmosphere is much thinner 600/101,300 then they would be ~ 11.33 grams per cubic meter. Note that it is the oxygen that drives chemical energy from rockets, so that the oxygen derived from CO2 that is more important than the Methane, I am not sure how rich Methane/O2 rockets are Kerosine runs rich and Hydrolox rockets a bit leaner, so that there is probably not a full burn to CO2 maybe half CO and CO2 in the output. The reason I say this is that to make methane on Mars will require water.

4H20 ---- >1.3V -----> 2H₂ + O₂  Chemical Electrolysis. This is a terribly energy inefficient reaction and is very slow.
Here are the production methods for hydrogen [https://en.wikipedia.org/wiki/Hydrogen#Production].

For each CO2 you turn to methane you will need 2H20 to be converted to Oxygen and hydrogen . . .you will need to store the oxygen as well as the methane, there is no condition on Mars were liquid oxygen and methane are stable as liquids so they will have to be cooled and pressurized.

The question of feasibility of Methane production is a choice with no alternatives, if they want to be able to return from Mars without have a devoted station in LMO, then they have to produce fuel on Mars. That does not mean that they can produce enough fuel to get back to Earth, but assuming that they bring or deposite enough equipment on Mars then it is plausible, if and only if they can find a source of water, there are low spots on Mars that would make getting the CO2 rather easy, up to 2 kPa of CO2, but getting the water would not be east at all.

 

One of the first BFRs can land near an exposed ice deposit and bring a rover with drills to harvest ice. The rover can have several tons of equipment, batteries, etc. Maybe a deployable solar array as well? It should harvest the ice, melt it, and then electrolyze the water, collecting both hydrogen and oxygen. Then drive back and refuel the ship somehow, repeat until done.

[FleshJeb]

Robert Zubrin and Pioneer Astronautics are probably the people you want to be looking at.

http://pioneerastro.com/Team/RZubrin/Mars_In-Situ_Resource_Utilization_Based_on_the_Reverse_Water_Gas_Shift_Experiments_and_Mission_Applications.pdf

Page 15, S/E-RWGS for scaling of components. These processes only require mining the atmosphere. The require that hydrogen be brought along, but each kg of hydrogen turns into 20kg of fuel.

From a Zubrin's 2011 addendum to The Case For Mars (I won't link it because it delves into specific politics):

• "The entire process takes ten months, at the conclusion of which a total of 108 tonnes of methane/oxygen bipropellant will have been generated."
• Requires "100 kilowatt nuclear reactor"

 

Edited January 24, 2018 by FleshJeb
speeeeling

[Hesp]

1 hour ago, PB666 said:

The question of feasibility of Methane production is a choice with no alternatives, if they want to be able to return from Mars without have a devoted station in LMO, then they have to produce fuel on Mars. That does not mean that they can produce enough fuel to get back to Earth, but assuming that they bring or deposite enough equipment on Mars then it is plausible, if and only if they can find a source of water, there are low spots on Mars that would make getting the CO2 rather easy, up to 2 kPa of CO2, but getting the water would not be east at all.

 

I'm wondering if they ever considered Propane instead than Methane.

It has a higher densification potential when subcooled (less tanks on the vehicle) and storage on Mars should be way simpler (boiling point at 1 bar: -42°C, basically Mars' mean temperature)

[PB666]

24 minutes ago, sh1pman said:

One of the first BFRs can land near an exposed ice deposit and bring a rover with drills to harvest ice. The rover can have several tons of equipment, batteries, etc. Maybe a deployable solar array as well? It should harvest the ice, melt it, and then electrolyze the water, collecting both hydrogen and oxygen. Then drive back and refuel the ship somehow, repeat until done.

What is the power supply to do this?

[sh1pman]

52 minutes ago, PB666 said:

What is the power supply to do this?

Not much to choose from, either solar or nuclear. 

[PB666]

And then you better bring alot of solar, maximum power production at high latitudes is on the order or 150 w/m². To make methane from CO2 and water requires a nickle catalyst and a temperature of 1000'C

[JohnDelvfar]

13 minutes ago, PB666 said:

And then you better bring alot of solar, maximum power production at high latitudes is on the order or 150 w/m². To make methane from CO2 and water requires a nickle catalyst and a temperature of 1000'C

thank you that is the kind of information i am looking for!  do you have any more information on the physical process?  i take it that the energy to accomplish the transformation comes from the heating of the catalyst but is there any other place energy is needed to further the reaction. I understand the cryonic's and pressurization process necessary to turn gaseous methane to liquid methane fuel and the energies required there. it is the making of the Methane from h2o and co2 that i am trying to get a handle on. the equipment necessary and the energies that need to be supplied.

Thanks everyone for your comment so far. I am looking forward to finding out more!

Edited January 24, 2018 by JohnDelvfar
spelling

[FleshJeb]

57 minutes ago, JohnDelvfar said:

thank you that is the kind of information i am looking for!  do you have any more information on the physical process?  i take it that the energy to accomplish the transformation comes from the heating of the catalyst but is there any other place energy is needed to further the reaction. I understand the cryonic's and pressurization process necessary to turn gaseous methane to liquid methane fuel and the energies required there. it is the making of the Methane from h2o and co2 that i am trying to get a handle on. the equipment necessary and the energies that need to be supplied.

Thanks everyone for your comment so far. I am looking forward to finding out more!

Except he's talking about outdated methods which are much more energy intensive. From the PDF (which apparently went unread) I referenced in my first post:

1. "Zirconia electrolysis process is quite simple. Carbon dioxide gas is heated to temperatures of about 1000 C" This is the old one.
    
2. "Reaction (1), known for over a century as the "Sabatier reaction," is highly exothermic and has a large equilibrium constant (~109) driving it to the right. It occurs spontaneously in the presence of either a nickel or ruthenium catalyst (nickel is cheaper, ruthenium is better) at temperatures above 250 C. (Typical reactors operate with peak temperatures around 400 C in the forward reaction zone, declining to 200 C at the exit.)" This was first suggested for ISRU in 1976, and popularized by Zubrin in the 1990s. See page 3 of the PDF for more details on the chemical reactions and heat required.
    
3. "Mars Direct manned mission propellant production could be done in three 10 liter pipe reactors. Operating at ~400 C" For an idea of scale. This is just for the Sabatier process, and doesn't include the electrolysis gear.
    
4. Power/Propellant:
   • Sabatier/Electrolysis: 166 W-day/kg
   • Zirconia electrolysis: 1562 W-day/kg
      
5.  Table that I referenced in my first post:
    

[JohnDelvfar]

FleshJeb

thank you for the information. For some reason i did not see your post until i refreshed the whole page. that is indeed exactly the information i was looking for.  i have been searching the net for diagrams or plans of a working piece of equipment without success as of yet. From this table i can see that just a simple flow system of the reactants over the catalyst will easily scale to what is needed

 

[kerbiloid]

There is also a difference between
the chemical experiment in a class (when you don't need pure methane, you just want to get a more-or less flammable gas),
the ISS waste utilization facility when you just throw out the methane-like product,
and high-purity methane to be sure that your engine won't stall in flight.

Also, not in milligrams, but in decatonnes.

The sabatiering is just the beginning of the process. It doesn't give pure metane, it gives a mixture of methane, carbon dioxide, carbon monoxide, water steam, soot, some traces of random parasite hydrocarbons, other junk gases.
The plant should separate the product and filter them out (because they can will change the engine characteristics and can just freeze inside the pump (because the methalox temperature is way below both water and carbon oxides melting points).

Industrially they use a set of coolers/exchangers and two-column separator with special agents to separate the hydrogen/hydrocarbon semi-products and carbon/sulfur oxides.
One column is a reactor where the agent takes the oxides from the semi-product, and another one is regenerator where the oxide-rich agent regenerates to be returned back.

As a bunch of columns from the chemical plant unlikely is appropriate (also on Mars it probably should be bigger due to low gravity and thus low vertical gradients), they probably should use a bunch of (even don't know, maybe centrifuges or so) to turn the gas mixture into something you can call a methane fuel.

 

4 hours ago, PB666 said:

And then you better bring alot of solar, maximum power production at high latitudes is on the order or 150 w/m².

100 kW/0.15 kW/m² = 667 m² = 26x26 m.

The rover could also use this solar panel as a sail!

[FleshJeb]

2 hours ago, kerbiloid said:

The rover could also use this solar panel as a sail!

Just for giggles, I looked up existing sail calculators and some aerodynamic physics. (I also checked that there wouldn't be any weird Mach effects. Turns out the speed of sound in an ideal gas barely varies with pressure.)

Aerodynamic force is directly proportional to pressure as well as area. So, you could use a (regrettably) Earth-bound sail calculator. Just multiply the area you input by the ratio of Mars pressure to Earth pressure.

[Racescort666]

10 hours ago, sh1pman said:

One of the first BFRs can land near an exposed ice deposit and bring a rover with drills to harvest ice. The rover can have several tons of equipment, batteries, etc. Maybe a deployable solar array as well? It should harvest the ice, melt it, and then electrolyze the water, collecting both hydrogen and oxygen. Then drive back and refuel the ship somehow, repeat until done.

Made me think of this.

9 hours ago, FleshJeb said:

Requires "100 kilowatt nuclear reactor"

Not totally unreasonable but it would be the largest nuclear reactor ever launched. For comparison, the SNAP-10A produced 30kW of thermal power and nominally was supposed to produce 500W of electricity (which it did before it was shut down due to a spacecraft problem unrelated to the reactor according to wiki). I assume that nuclear power scales up pretty easily since the smallest ship reactor I found power numbers for is 74MW. Therefore, 200X the capacity of SNAP-10A is 6MW thermal and 100kW electrical. I have no idea what it would weigh but 200X SNAP-10A would be 58t. Crazy heavy but within the handwaving range of BFR. 

There are however several points to be made to this that would decrease the size of the reactor:

• SNAP-10A has only 1.7% thermal-electrical efficiency, most RTGs are around 5%
• If you're going to build a reactor, go all out and use a heat engine rather than using thermalelectric effect. Efficiencies as high as 25% are not unreasonable
• 100kW does not specify if it is thermal energy or electrical energy and many of the processes require heat
• Also, this power could be spread out over multiple reactors which would probably be smart anyway

4 hours ago, kerbiloid said:

100 kW/0.15 kW/m² = 667 m² = 26x26 m.

Don't forget that solar panels are only ~15%-20% efficient so... 667 m²/0.15 = 4447 m² =  67X67 m o_O 

[Green Baron]

3 hours ago, FleshJeb said:

Just for giggles, I looked up existing sail calculators and some aerodynamic physics. (I also checked that there wouldn't be any weird Mach effects. Turns out the speed of sound in an ideal gas barely varies with pressure.)

Aerodynamic force is directly proportional to pressure as well as area. So, you could use a (regrettably) Earth-bound sail calculator. Just multiply the area you input by the ratio of Mars pressure to Earth pressure.

While this is all true, solar sails and aerodynamic sails are not comparable. There is one special case where an aerodramatic sail works only by the pressure of the wind on a downwind course, but this is rarely the case and even avoided when sailing because it is the most inefficient course and demands full attention when doing so with the usual fore and aft sails.

 

Edit: ignoring the low Marsian pressure, a wind sail needs to be adjusted to the wind conditions and the course, which would be counterproductive to solar power generation in which case it needs to be adjusted towards the sun. Also flexible solar panels are less effective than rigid, subtracting more from the already low efficiency on Mars.

Edited January 24, 2018 by Green Baron

[StrandedonEarth]

12 hours ago, FleshJeb said:

• Requires "100 kilowatt nuclear reactor"

 

So about ten Kilopower units then.

[Green Baron]

2 hours ago, Racescort666 said:

Don't forget that solar panels are only ~15%-20% efficient

More than double that.

https://en.wikipedia.org/wiki/Multi-junction_solar_cell

Theoretic maximum ~70%. Which other technology can reach that ?

Edited January 24, 2018 by Green Baron

[PB666]

Gee, I leave the discussion for 12 hours and my the little logic sprites come bounding out of the wood work.

First, since the Methanogenesis reaction cannot occur at low temperature is a vacuum or just sitting there it all assumes you brought along a reactor vessel, one that can be turned (rolled around it axis), and that you can both purify and store the reaction product. Since it assumes that you will liquify the methane you need an LNG plant. Also the water needs to be separated.

The electrolysis reaction requires 2e- per mole/n of water. The book value is 2.37 x 10⁵ J per mole 55.5556 = 1.327 x 10⁷ J/kg. The maximum theoretical efficiency is 90%. So . . . . ~15 MJ per Kg

4H₂ + CO₂ ------> CH₄ + 2H₂0  It takes 8kg of hydrogen to make 16kg of Methane

If we look at a BFR and the amount of methane require. 240,000 kg x 8/16 x 15 MJ per Kg = 1.8 TJ of energy required to fuel a BFR. And BTW

If we divide this by the number of seconds in a typical daylite day then its roughly thats 62.5 Megawatts of power (416 thousand 1 meter solar panels). IF we consider the minimal weight of a solar panel is 1 kg (A very generous reduction in current mass), then that is a landing on Mars weight of 416 kT, but the other problem is that not all that energy goes into the formation of Methane, about half the energy goes into heat during methanogenesis

So lets say that we only could afford 1 ton of solar panels (31 x 32 m of solar panels), then it would take 416 martian days. If the plan is to land in a polar region and extract water from Ice, then increasee the time. Mar's tilt is higher than Earths and there are many areas that go dark in its winter. And remember that those 1 kg per square meter panels just lie flat on the ground, there is no provision for tracking, stands or brackets, these require added mass.

The maximum power output of NTGs is typical 10 kW, so even if you decided to do this in 100 days, you still need 625 kW/day which means you would need 62 of them, and the nuclear thermal generators are not cheap in terms of weight either, you wont find a 10kW generator for 10kg.

So lets consider all of the costs

1. Finding water piping  and the cost of pressurizing atmosphere to remove CO2
2. The weight cost of the equipment for #1
3. The weight cost of solar panels and weight cost of the electrolysis equipment (not discussed)
4. The cost of storing hydrogen and oxygen (presumably at some point liquified and oxygen scaveging equipment to keep it liquified)
5. The weight cost of a methanogensis reactor, the weight cost of cooling the reactor.
6. The weight cost of storing methane and at some point liquifying it.
7. The energy cost for cryogenesis.
8. The weight cost of systems for deploying solar panels and cooling equipment, carbon capture, and water drilling. (to have a well you have to have a drill).
Assuming that many operations will be Roboticized.

So in the Musk Video is shows a Martian City and growing  . . . . . .
The problem is that Cities require water, and so do space craft, you can recycle the water in  a city but not in a spacecraft. So that if you plan to have a city, you best get your spacecraft water elsewhere.

9. The cost of reaching out from the base site (as shown in the video) to find water and transport the water back to the base.

 

 

 

 

Edited January 24, 2018 by PB666

[Green Baron]

To generate 60MW on Mars with upper range consumer grade solar panels near the equator you'd need around 300,000 m² of them (divide by area/panel), less with the better ones mentioned up in the thread. They only need dusting and an exchange no earlier than in 20 years.

Or 6,000 of the 10KW nuclear reactors.

 

Edit: Solar power generation near the Marsian poles isn't possible/practical.

 

Edited January 24, 2018 by Green Baron

[PB666]

I am considering the average location, IOW where ever the water is, not where the sunlight is.  . . . . . .

The average I take at 150 w/meter^2. If I am not mistaken the panels on the ISS are 2?? watt per square meter, and again Mars is 3/2 the distance so its basicaly 4/9th that on Earth, so 150w/sq.meter is being generous with what is being placed in space.

We have to remember one thing, if you are hauling solar panels all the way from Earth to Mars, you could bring the most efficient which is 42% (@622 W/meter) then you are basically going to have 261 watts per meter _But_ that efficiency declines quickly because of the instability and hole problems. If you take the most stable panel they will last longer 25 to 50 years, potentially 75 is you use very expensive contacts for electrical conduction but their efficiency is going to be low. The highest efficiency panels lose 15% of their efficiency within 100 solar days and decline slowly after that.

They are not going to haul the solar panels back or abandon them, that would be dumb. Panels that last a long time are desired. The second thing is that you do want panels that tilt, tilting is very useful, although there is not much dust suspended in the martian atmosphere, when there is dust there tends to be alot of it (winds sometimes blow in the 2 and 3 magnitude range), and thus you want to to tilt those panels to an inverted angle. So that the weight estimate is actually an under estimate for any long term use of panels. There is a third problem with panels on Mars that is far less of a problem on Earth. CO2 the major gas on mars is not really a magnetic dipole and it lacks polarity, while there is a two minipoles in CO2 they offset each other. Thus the magnetosphere does very little work on CO2 and thus CO2 provides little shield, and although it can pass current it generally could be considered an insulator again, putting electrons on either oxygen is not going to be a thing since the Oxygens are electron withdrawing, you might get an electron to bind the carbon or a proton to delta+ on the oxygen but again not a great charge carrier in the martial atmosphere, ionizing CO2 therefore would not either be easy and little work it expected. Although, I must point out that scientist believe that Mars has lost CO2 as a result of ionization and magnetic forces, this is slow relative to water. From this consideration the magnetic and electric fields that give rise to the power within solar storms is not going to be sufficiently deprecated in the Martian atmosphere to protect sensitive electronics, and the voltage potential across any sufficiently long object is expected to be, at times (very very brief periods of time) to be extreme, extreme enough to damage electronics (which typically have sensing voltages of 5 or less).

As a consequences during any intense ION storm we expect electrical pressure along traverses on  Mars. For long term panel stability this is a problem, on  the Hayabusa spacecraft two of the panels were rendered inoperable because of the dark-spot activity. The ISS is largely immune because its orbit is close to Earth, but any true polar spacecraft can expect this (an maybe a reason that there are almost no true polar spacecraft). So having 1 meter wide panels is not very wise, smaller panels that have scavenger wires of alternating positive and negative wires would protect the panels by attracting current to the wires and into some kind of current buffer. There's another problem also, because if you are using large panels you want to use huge step voltages, and this compounds the problem, versus smaller panels the voltage is lower but carry more amps and has some excess capacity. Imagine that we have a step voltage of say 1400 V, which will be the case at the edge of some (the last) p-type semiconductor, then this would be extremely attractive to any negatively charged IONs coming in from space, if the n-type connector is harder to access, then the corresponding positive charge will have an extreme attraction to any part of the system that is less insulated. If you are running alot of isolated parallel panels then they are easier to shield and if one is damaged the damage will be less damaging to the entire system.

I consider 150 W/panel at a kg per meter  for a large protective system to be very generous. This idea that we can have a roll out of a panel of say 0.00001 to 0.001 meter thickness is not feasible on mars unless you already have some protective enclosure for the panel, not realistic

This is why I say, don't tell me anything you are going to do on Mars without first telling me how you are going to power it. Power = f(mass) and acceleration = thrust / mass and also dV=f(acceleration)*burn time. If someone handwaves in alot of power, I have to handwave behind Their back -dV.

 

Edited January 24, 2018 by PB666

[kerbiloid]

18 minutes ago, PB666 said:

If I am not mistaken the panels on the ISS are 2?? watt per square meter

According to wiki, ~30+/-5 W/m².

(84..120 kW) / 8 arrays 35x12 m.

[PB666]

16 minutes ago, kerbiloid said:

According to wiki, ~30+/-5 W/m².

(84..120 kW) / 8 arrays 35x12 m.

You've made an error, I will figure it out.
 

Its 32.8 kW per solar array of 34x12 at maximum power, (80 kw/meter) I think that one solar array is nearly always in the Normal position (not relevant).

16,400 solar cells in 8x8cm = .08 x .08 = 0.0064 m²    so total area exactly is 104.96 m² These are then spread into 35x12 meters by sets of folds and joins.
If we look just at power production per solar cell area its 320 watt per meter, if we were to convert this to mars its

(149/227)² * 320 = 137.87. So that if we were using the ISS's solar cells, perfectly compacted to form a continuous place, its 137.87 watts per sq.meter.

 

Edited January 24, 2018 by PB666

[Green Baron]

Solar constant for Mars is 600W/m² (a little less than 1/2 that of earth) but atmospheric scattering is lower. Near the equator there'd be no problem with getting the maximum of a panel (peak only of course !) ~30-40% of that as electricity, assuming the latest generation solar panels. The ISS panels are out of style, like a pc from 2006 ;-) Seriously, several generations have past since then. Good household ones are better these days (25% are the ISS panels i read somewhere but can't remember where).

But of course: conversion losses, excess panels and storage for nighttimes make it difficult. But then again, a failing nuclear device needs replacement or repair as well. And solar panels aren't dangerous at all. But will probably not work at latitudes 50° and higher ...

Edited January 24, 2018 by Green Baron

[kerbiloid]

13 minutes ago, PB666 said:

You've made an error, I will figure it out.

https://en.wikipedia.org/wiki/Electrical_system_of_the_International_Space_Station

Quote

Each ISS solar array wing (often abbreviated "SAW") consists of two retractable "blankets" of solar cells with a mast between them. Each wing uses nearly 33,000 solar cells and when fully extended is 35 metres (115 ft) in length and 12 metres (39 ft) wide.^[1] When retracted, each wing folds into a solar array blanket box just 51 centimetres (20 in) high and 4.57 metres (15.0 ft) in length.^[2] The ISS now has the full complement of eight solar array wings.^[3] Altogether, the arrays can generate 84 to 120 kilowatts.^[4]

 

[PB666]

5 minutes ago, Green Baron said:

Solar constant for Mars is 600W/m² (a little less than 1/2 that of earth) but atmospheric scattering is lower. Near the equator there'd be no problem with getting the maximum of a panel (peak only of course !) ~30-40% of that as electricity, assuming the latest generation solar panels. The ISS panels are out of style, like a pc from 2006 ;-) Seriously, several generations have past since then. Good household ones are better these days (25% are the ISS panels i read somewhere but can't remember where).

But of course: conversion losses, excess panels and storage for nighttimes make it difficult. But then again, a failing nuclear device needs replacement or repair as well. And solar panels aren't dangerous at all. But will probably not work at latitudes 50° and higher ...

Well let's just see, I calculated the power output of 137 watts per meter at 22.8% OK so lets see what power efficiency is for space ready solar materials.

(Reference: National Renewable Energy Laboratory (NREL) - National Renewable Energy Laboratory (NREL), Golden, CO − United States Department of Energy website image explanatory notes)

And we select the highest of space stable of 33%, so that we can get 200 watts. Again this is only going to be, for a panel lying on the ground, 1/3rd of a Martian day. So that average power production per day per meter is going to be 66.6 W.
But I have to state that no solar panel in space (or Mars) will ever get this even, because the panels are drawn out over an area that contains diodes, joints wiring ect. On the ISS solar arrays the panels form less that 1/3rd of the area, so you're not going to be able to hand wave those wastes away.

I repeat that thin film solar arrays are only feasible if you have already in place a regime of power conduction end stochastic event protection (dust and storm abatement) if you don't have the weight for these in the system, you are essentially digging a hole on Mars and throwing solar panels into them.