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Solar cells have exactly the same power rating on earth as in space surely? What would change is their capacity factor and so energy generation.
by __alexs 9mo ago
Solar 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 9mo agoThe atmosphere is in the way, and they get pretty dirty on earth. Also it doesn't rain or get cloudy in space
- __alexs 9mo agoSure but like, just use even more solar panels? You can probably buy a lot of them for the cost of a satellite.
- deleted 9mo ago[deleted]
- rcxdude 9mo agoThe cost of putting them up there is a lot more than the cost of the cells
- schiffern 9mo 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 9mo 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 9mo 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 9mo agoAnd in geostationary, the planet hardly ever gets in the way. They get full sun 99.5% of the year.
- XorNot 9mo 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 9mo 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 9mo 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 9mo agoMy response is already contained in my comment above, in the sentences after the first.
- deleted 9mo ago[deleted]
- fuzzfactor 9mo 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 9mo 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 9mo agoI don't disagree
- DoctorOetker 9mo 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 9mo 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 9mo ago[deleted]
- kortex 9mo 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 9mo 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 9mo 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 9mo 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 9mo 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 9mo 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 9mo 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?