11 ms·
In fairness, solar cells can be about 5x more efficient in space (irradiance, uptime).
by moeadham 8mo ago
In fairness, solar cells can be about 5x more efficient in space (irradiance, uptime).
- __alexs 8mo agoSolar cells have exactly the same power rating on earth as in space surely? What would change is their capacity factor and so energy generation.
- bastawhiz 8mo agoThe atmosphere is in the way, and they get pretty dirty on earth. Also it doesn't rain or get cloudy in space
- __alexs 8mo agoSure but like, just use even more solar panels? You can probably buy a lot of them for the cost of a satellite.
- deleted 8mo ago[deleted]
- rcxdude 8mo agoThe cost of putting them up there is a lot more than the cost of the cells
- schiffern 8mo ago>just use even more solar panels I think it's because at this scale a significant limit becomes the global production capacity for solar cells, and SpaceX is in the business of cheaper satellites and launch.
- skywhopper 8mo ago“This scale” is not realistic in terms of demand or even capability. We may as well talk about mining Sagittarius A* for neutrons.
- schiffern 8mo agoYou don't even need a particularly large scale, it's efficient resource utilization. Humanity has a finite (and too small) capacity for building solar panels. AI requires lots of power already. So the question is, do you want AI to consume X (where X is a pretty big chunk of the pie), or five times X, from that total supply? Using less PV is great, but only if the total cost ends up cheaper than installing 5X the capacity as terrestrial PV farms, along with daily smoothing batteries. SpaceX is only skating to where they predict the cost puck will be.
- DennisP 8mo agoAnd in geostationary, the planet hardly ever gets in the way. They get full sun 99.5% of the year.
- XorNot 8mo agoBoosting to geostationary orbit knocks a big chunk out of your payload capacity. Falcon 9 expendable will do 22 tons to LEO and about 8 tons to GTO.
- DennisP 8mo agoThat's still a smaller ratio than the ~4X gain in irradiance over LEO. But if you're doing it at scale you could use orbital tugs with ion drives or something, and use much less fuel per transfer. It's probably not competitive at all without having fully reusable launch rockets, so the cost to LEO is a lot lower.
- XorNot 8mo ago8 tons over 22 is a little over 1/3rd the original payload to LEO. If 4x the solar generation potential (not irradiance - the sun is not 4x brighter in space at Earth's orbital radius) is the reward, that's putting an incredible premium on a 3x multiplier on launch costs per kg (at minimum - likely higher, you're also inheriting a worse radiation environment). But those two parameters are not equals: 3x the cost per kg is a much higher number then 4x the solar power.
- DennisP 8mo agoMy response is already contained in my comment above, in the sentences after the first.
- deleted 8mo ago[deleted]
- fuzzfactor 8mo agoI'm all for efficiency, but I would think a hailstorm of space junk hits a lot harder than one of ice out on the farm. Except it doesn't melt like regular hail so when further storms come up you could end being hit by the same hail more than once :\
- PunchyHamster 8mo agoeven at 10% (say putting it on some northen pile of snow) it is still cheaper to put it on earth than launch it
- bastawhiz 8mo agoI don't disagree
- DoctorOetker 8mo agowould you prefer big tech to piss their waste heat into your rivers, soils and atmosphere? or would you prefer them to go to the bathroom upstairs? at some point big tech is in a "damned if you do, damned if you don't" situation...
- mrguyorama 8mo agoHere in Maine in the depths of winter (late December), 1 m^2 of ground can collect 4 kwh per day (weird units). That's why people are trying to build solar here. Our power is expensive due partially to failing to build basically any new generation, and some land is very cheap, and the operational cost of a solar farm is minuscule. Solar farming is basically an idle game in real life and my addiction is making me itchy. You can overprovision, and you should with how stupidly cheap solar is. That we aren't spending billions of Federal dollars building solar anywhere we can, as much as we can, is pathetic and stupid and a national tragedy. We got so excited about dam building that there's no where to build useful dams anymore, and there is significant value to be gained by removing those dams, yet somehow we aren't deploying as much solar as we possibly can? It's a national security issue. China knows this, and is building appropriately. The southwest should be generating so much solar power that we sequester carbon from the atmosphere simply because there is nothing else left to do with the power.
- deleted 8mo ago[deleted]
- kortex 8mo agoSatellites can adjust attitude so that the panels are always normal to the incident rays for maximum energy capture. And no weather/dust. You also don't usually use the same exact kind of panels as terrestrial solar farms. Since you are going to space, you spend the extra money to get the highest possible efficiency in terms of W/kg. Terrestrial usually optimizes for W/$ nameplate capacity LCOE, which also includes installation and other costs.
- tasty_freeze 8mo agoFor one or a few-off expensive satellites that are intended to last 10-20 years, then yes. But in this case the satellites will be more disposable and the game plan is to launch tons of them at the lowest cost per satellite and let the sheer numbers take care of reliability concerns. It is similar to the biological tradeoff of having a few offspring and investing heavily in their safety and growth vs having thousands off offspring and investing nothing in their safety and growth.
- Waterluvian 8mo agoAtmospheric derating brings insolation from about 1.367KW/m2 to about 1.0. And then there’s that pesky night time and those annoying seasons. It’s still not even remotely reasonable, but it’s definitely much higher in space.
- shagie 8mo ago> And then there’s that pesky night time and those annoying seasons. The two options there are cluttering up the dawn dusk polar orbit more or going to high earth orbit so that you stay out of the shadow of the earth... and geostationary orbits are also in rather high demand.
- Waterluvian 8mo agoPut them super super far away and focus all the energy into one very narrow death laser that we trust the tech company to be careful with.
- crabmusket 8mo agoSolar modules you can buy for your house usually have quoted power ratings at "max STC" or Standard Testing Conditions, which are based on insolation on Earth's surface. https://wiki.pvmet.org/index.php?title=Standard_Test_Conditions_(STC) https://wiki.pvmet.org/index.php?title=Standard_Test_Conditi... So, a "400W panel" is rated to produce 400W at standard testing conditions. I'm not sure how relevant that is to the numbers being thrown around in this thread, but thought I'd provide context.
- __alexs 8mo agoThat's super interesting. STC uses an irradiance of irradiance 1000W/m2, in space it seems like you get closer to 1400W/m2. That's definitely better, but also not enormously better. Seems also like they are rated at 25C, I am certainly not a space engineer but that seems kind of temperate for space where cooling is more of a challenge. Seems like it might balance out to more like 1.1x to 1.3x more power in space?
- bastawhiz 8mo agoAnd how much of that power would be spent on high speed communications with Earth that aren't, you know, a megabit or two per second
- chaos_emergent 8mo agoI grew up on a rural farm in California with a dial-up connection that significantly hampered my ability to participate in the internet as a teenager. I got Starlink installed at my parents' house about five years ago, and it's resulted in me being able to spend considerably more time at home. Even with their cheapest home plan, we're getting like 100 Mbps down and maybe 20 to 50 up. So it's just not true at all that you would have connections that are a megabit or two per second.
- bastawhiz 8mo agoThat's not what I'm suggesting. The post says "deep space". If you're going to try to harvest even a tiny percentage of the sun's energy, you're not doing that in Earth's orbit. The comparison is a webcam feed from Mars.
- crote 8mo agoThat's pretty much a solved problem. We've had geostationary constellations for TV broadcast at hundreds of megabytes for decades now, and lasers for sat-to-sat comms seems to be making decent progress as well.
- bastawhiz 8mo ago> it is possible to put 500 to 1000 TW/year of AI satellites into deep space, meaningfully ascend the Kardashev scale and harness a non-trivial percentage of the Sun’s power Which satellites are operating from "deep space"?
- _n66o 8mo agoThose are for video. AI Chat workflows use a fraction of the data.
- cowsandmilk 8mo agoIt is more than 5x less expensive to get surface area on earth’s surface.
- bob1029 8mo agoRight now it is. However, the amount of available land is fixed and the demand for its use is growing. Solar isn't the only buyer in this real estate market.
- JeremyNT 8mo agoWe have so much excess land with no real use for it that our government actually pays farmers to grow corn on it to burn in cars. Availability of land for solar production isn't remotely a real problem in the near term.
- moralestapia 8mo agoThis. I feel like everyone just lost their mind.
- doctorwho42 8mo agoYou just have to remember, most of these people live in high density regions and have little comprehension about how much surface area humanity truly occupies... And that isn't even accounting for offshore constructs.
- rainsford 8mo agoThe Technology Connections Youtube channel recently did a great video arguing pretty convincingly that the land used to grow corn for cars would be vastly more efficiently used from an energy perspective if we covered it with solar panels.
- recursivecaveat 8mo agoThis is really underselling it tbh. Any land that's growing corn in a developed country is likely top 1% of land on earth. Half of the earth is desert and tundra. Which is still incredibly easier to work with than space because you can ship there with a pickup very cheaply. Maybe when nevada and central australia are wall-to-wall solar panels we can check back on space.
- ben_w 8mo agoThe quoted "1 TW of photovoltaic cells per year, globally" is the peak output, not the average output. They're only about 20% higher peak output in space… well, if you can keep them cool at least.
- pantalaimon 8mo agoBut there are no clouds in space and with the right orbit they are always facing the sun
- jrk 8mo agoThe 1TW is the rated peak power output. It's essentially the same in space. The thing that changes is the average fraction of this sustained over time (due to day/night/seasons/atmosphere, or the lack of all of the above). It's still the same 1TW theoretical peak in space, it's just that you can actually use close to that full capacity all the time, whereas on earth you'd need to over-provision substantially and add storage, so 1TW of panels can only drive perhaps a few hundred GW of average load.
- singleshot_ 8mo ago> the whole capacity Wouldn’t something like half of the panels be in shadow at any time?
- ben_w 8mo agoDepends where you put them. The current vogue option is a sun-synchronous orbit: https://en.wikipedia.org/wiki/Sun-synchronous_orbit https://en.wikipedia.org/wiki/Sun-synchronous_orbit
- WalterBright 8mo agopolar orbit
- deleted 8mo ago[deleted]
- philistine 8mo agoDoes that include all the required radiators to vent heat?
- chartisma 8mo agoand of course, the continuous opposite boost needed to prevent the heat vent from knocking them out of orbit.
- virgildotcodes 8mo agoI think this is all ridiculous, to be clear, but re: this problem couldn't the radiators in theory be oriented so that they vent in opposite directions and cancel out any thrust that would be generated?
- tenuousemphasis 8mo agoNow do waste heat.
- deleted 8mo ago[deleted]
- DoctorOetker 8mo agoHere you go: https://news.ycombinator.com/item?id=46862869 https://news.ycombinator.com/item?id=46862869
- sltkr 8mo agoFortunately there are no downsides to launching solar cells into space that would offset those gains.