Solar Energy now following inverse square law

[RuBisCO]

I notice that I was not getting the solar power I got in previous version out in Jool space. So I checked with a solar escape probe, turns out solar power now follows the inverse square law. So for example the KSP wiki still states that out at Jool you receive 50% the power you receive at kerbin, but now it is 3-4%

This changes game play radically! Solar power is virtually useless out beyond Duna. How is laythe warm enough to be wet?

[Bill Phil]

This isn't new news.

Laythe is getting tidal heating, plus salt in the oceans and a whole bunch of "science".

[RuBisCO]

This isn't new news.

Laythe is getting tidal heating, plus salt in the oceans and a whole bunch of "science".

Well I don't think that is very realistic but that not really the big problem: The game lacks any viable power source out their other then RTGs and RTGs can't really cut it for the power demands of mining and and research labs.

[ghpstage]

Theres also fuel cells and the larger fuel cell arrays. Fuel cells output 1.5 EC/sec, and arrays 18EC/sec. A few arrays will fuel anything and are pretty efficient in terms of fuel use, using just 0.02/sec.

[dryer_lint]

You've also got fuel cells, but yeah, RTGs are your only choice at that point. Also, a tip for power usage: "locked" batteries can be re-enabled even when your probe is out of power, so they're really useful as emergency or long-term energy storage. Took me way too long to figure this out...

[RuBisCO]

Question: can fuel cells power a miner, extracting and converting ore too fuel faster then it burns it?

I'll test that and find out.

[ghpstage]

I don't have much experience using ISRU so I couldn't tell you, will depend on engineer's skill and the areas resource density.

A quick test in sandbox is pretty encouraging, a max level engineer (Its meant to be a sandbox, why can't we edit Kerbal's level ) can mine ore out of the launchpad much, much faster than its burnt by the cells.

Edited May 9, 2015 by ghpstage

[RuBisCO]

Well it works off fuel cells. The ISRU converts many times more ore to fuel then is consumed to power it all, not very realistic but it does make for interesting game play dynamics: now in order to get any thing done in deep space (lab research) will require mining to power it.

[Brotoro]

Ugh. I shan't be doing that.

[Xavven]

Be aware that solar panels reduce their power generation as they overheat. There's a certain planet that might surprise you *hint hint*

[Foxster]

You can generate a LOT of electricity from a small amount of LF+O with a fuel cell. Jool-area missions is what they were introduced for. Doesn't help with long-life bases of course, which leave PB-NUKs or doing some mining as the only other solution.

[Spatzimaus]

You can generate a LOT of electricity from a small amount of LF+O with a fuel cell. Jool-area missions is what they were introduced for.

The problem with this is, what about orbital probes? Without a way to replace the LFO, a fuel cell isn't really an option for something like a ScanSat mapping satellite that stays in orbit for a long time but has an ongoing energy cost. I've got a 4-ton ion probe I designed for these missions, but look at its power problem: ~2.5 energy/sec for the scanners isn't a huge amount. A small 1x6 solar panel produces 1.6e/s at Kerbin, but at Jool you divide that by 25, giving 0.064 at best. Even with 16 of them I'd only produce about 1.0e/s assuming perfect exposure (not going to happen with that many), so I have no choice but to load on several RTGs (0.75e/s apiece) instead for anything heading out to Jool or beyond. Sure, each RTG has as much mass as five of the 1x6 arrays, but it's still negligible compared to the size of a vehicle as a whole.

I'm not saying that they should go back to the old equation, but it does mean that solar panels seem almost useless now for anything that isn't explicitly designed only to go to the inner planets. The base energy production numbers might just need a bit of tweaking to keep solar power viable.

[Grumman]

If they did change it, they could make it something like 1/x^1.5 instead of 1/x^2. That would make solar panels 1/11th as efficient at Jool instead of 1/25th as efficient.

[Brotoro]

We need a nice little nuclear reactor (with radiators, of course).

- - - Updated - - -

Here you go...A really crappy "nuclear reactor":

It's 49 PB-NUKs in a box...with what I like to picture are radiators.

Mass 4.9 tones...But it will continuously run two drills and one ISRU refinement unit (in the dark).

But that's much worse than a real reactor part could do.

Edited May 12, 2015 by Brotoro

[Othuyeg]

You can use a liquid fuel engine to produce electricity. The LV-N provides 5 electric units per second at full throttle (overheating issue to be kept in mind)... I don't have the game on my laptop and the wiki does not have the required numbers but I wonder if it would be possible to power a drill by having an LV-N facing the ground next to a drill.

Edit: Yes, I know it is not in any way sensible seeing as we have fuel cells. But it is the KERBAL WAY!

Edited May 12, 2015 by Othuyeg

[Maolagin]

I'm not saying that they should go back to the old equation, but it does mean that solar panels seem almost useless now for anything that isn't explicitly designed only to go to the inner planets. The base energy production numbers might just need a bit of tweaking to keep solar power viable.

Yes, that's kind of the point. In the real world, solar power really is almost useless out past Mars. JUNO in particular is a groundbreaking mission precisely because it was able to combine the latest panels with the latest low power electronics to pull off a very basic solar powered mission at Jupiter. Before that, everything that has flown beyond the asteroid belt has been radioisotope powered.

[Spatzimaus]

Yes, that's kind of the point. In the real world, solar power really is almost useless out past Mars.

I'm perfectly aware of the physics involved, as I'm an astronomer by profession. The thing is, KSP has already changed quite a few other things for the sake of gameplay, primarily due to one single factor: only the active vessel can apply thrust, and only when it's not in time warp. While it sounds simple, in practice this has a couple significant effects:

1> Maneuvers are done at nodes. In reality a manned trip to somewhere like Mars could apply a low amount of thrust for the entire transfer, but in KSP the thrust is all done at once and then the vessel coasts until it enters the SOI and has to do an insertion burn. For a renewable resource like electricity, that means your vessel needs enough generation and/or battery capacity to handle the entire burn in a short period.

and more importantly for this discussion,

2> In the real world an ion drive has a ridiculously low thrust (several orders of magnitude below KSP's version), which also means they don't have to use huge amounts of electricity for a burn in the first place.

If you want to make something like an ion-propelled probe that can visit the outer planets using the real world's engineering efficiencies, it wouldn't need to stack a dozen RTGs and/or dozens of solar arrays just to power a single small engine. Primarily thanks to the 0.23 thrust increase (a factor of 4 difference), though, one KSP ion engine now uses about 8.5e/s, while one RTG only produces 0.75 and we've already discussed how ineffective the solar panels are. So, you end up stacking a ton of RTGs (at a ridiculous cost) for each ion engine, or use an appalling number of solar panels.

The point is, it all depends on what the developers' concept of an ideal unmanned probe is. If it's supposed to be something with an ion engine, one RTG, four small solar arrays, and a few batteries, then you'd get something that'd look approximately like a real-world probe. But, that sort of design can't even produce one quarter of the electricity needed to offset an ion's thrust. Sure, if we could set the probe to 10% throttle and timewarp (or switch to something else) then it'd be different, but we can't, and the developers already made it clear with the new resource scanning system that they're not fans of the "go make a sandwich" type of gameplay. So, for gameplay reasons the current electrical generators need to be boosted substantially just to keep ions viable as a propulsion system.

[Thahat]

Question: can fuel cells power a miner, extracting and converting ore too fuel faster then it burns it?

I'll test that and find out.

YES, even on kerbin, right on the launchpad. at least if you use the large array-style fuel cells.

i think i had 6 drills, one large converter, and 3?4? large fule cells (experiment with how many need to be on)

and it came out positive. though you do need some initial fuel to work with and preferably a large battery so if you mess up you dont instantly drain all your power.

[brdavis]

I'm perfectly aware of the physics involved, as I'm an astronomer by profession.

It's seems ironic that I was really happy to hear that solar power was dropping as an inverse square law… because I'm a physics and astronomy professor and was always really annoyed that solar cells behaved the way they previously did in the game. Trying to explain to my students was made harder by the previous design choice… where the current (1.0.2) design choice forces consideration of a new set of trade-offs.

for gameplay reasons the current electrical generators need to be boosted substantially just to keep ions viable as a propulsion system.

I don't actually see that - for one thing I can't think of any mission that has used (or has proposed using) ion engines beyond about Mars. For another, you've got a point that some of the game mechanics "break" ion engines (like no continuous thrust mission profiles), but I'm not convinced "breaking" the inverse square law is a good solution to other problems. Honestly the biggest problem I see with it is not propulsion for small probes way out in the beyond, but power sources. RTGs are *great* things (and you can store up a lot of power for a short time… yep, ion burns may be power limited, what's wrong with that), but supplying a base is another story. A compact true reactor might be handy in this regard, but could certainly be added by a mod too.

[Jesrad]

Well it works off fuel cells. The ISRU converts many times more ore to fuel then is consumed to power it all, not very realistic

Actually, it is realistic. If it took more energy to refine the ore, than you could get from the refined fuel, you'd be better off just using your input energy directly, than bother mining at all in the first place. And there would be no oil industry on Earth.

[egoego]

I found the old solar panels were to overpowered. I could not find a use for the large XL thing besides for the looks. I was able to power a whole space station in Kerbin orbit with just one OX panel.

The new system does change a lot when it comes to electric power, but it is challenging and therefore fun

[Kerbart]

Well I don't think that is very realistic but that not really the big problem: The game lacks any viable power source out their other then RTGs and RTGs can't really cut it for the power demands of mining and and research labs.

Have you checked the moons of Jupiter? Same thing happens there. And your wishes about realism have been granted: solar panels ARE lacking further away in the solar system and RTG's really DON'T cut it for large power demands. Welcome to deep space exploration!

[Maolagin]

I'm perfectly aware of the physics involved, as I'm an astronomer by profession. The thing is, KSP has already changed quite a few other things for the sake of gameplay, primarily due to one single factor: only the active vessel can apply thrust, and only when it's not in time warp. While it sounds simple, in practice this has a couple significant effects:

Yeah, I'm sorry that my reply came out so flippantly. I didn't mean to imply that you don't! Funny, I'm also an astronomer and occasional spacecraft engineer. How many of us are on here, anyway?

1> Maneuvers are done at nodes. In reality a manned trip to somewhere like Mars could apply a low amount of thrust for the entire transfer, but in KSP the thrust is all done at once and then the vessel coasts until it enters the SOI and has to do an insertion burn. For a renewable resource like electricity, that means your vessel needs enough generation and/or battery capacity to handle the entire burn in a short period.

and more importantly for this discussion,

2> In the real world an ion drive has a ridiculously low thrust (several orders of magnitude below KSP's version), which also means they don't have to use huge amounts of electricity for a burn in the first place.

So the message I was responding to was about powering scanners and such, and that probably should be hard to do with solar. That said, the issue of ion-engine realism was and is a curious rabbit-hole with both the old and the current solar power curve.

I'm willing to assume there's good technical reasons why "thrust in the background during timewarp" is hard to implement. Given that batteries are cheap and pretty light, that batteries *do* recharge during timewarp so long as the craft is loaded, and given that ion engines have drastically higher thrust and electricity consumption than is realistic, it seems to me that the intended approximation to real ion missions is the one we have right now: load up on batteries, run them to empty with the ion thrusters, then recharge on timewarp. Rinse and repeat until desired delta-V is achieved, or do it periodically during cruise.

[Grumman]

I'm willing to assume there's good technical reasons why "thrust in the background during timewarp" is hard to implement.

I'd expect it's not the thrust but all the other interactions that happen when under load that makes it hard to implement. But there's no real reason why you couldn't declare make ion drives an exception and just not calculate any of the hard stuff during timewarp on the basis that ion drives are too weedy and use too little fuel to have a significant effect on stresses, ship mass or CoG.

[Sky_walker]

To give you a sense just how long do the ions burn in space, here is a trajectory of NASA Dawn probe equipped with ion engines:

But there's no real reason why you couldn't declare make ion drives an exception and just not calculate any of the hard stuff during timewarp on the basis that ion drives are too weedy and use too little fuel to have a significant effect on stresses, ship mass or CoG.

There's many, many fundamental reasons why it's not possible. But let give me you just one to consider - how exactly are you going to synchronize your rotation with the trajectory around the sun? You don't realize the amount of precision required. To end this quickly: KSP just wasn't build to allow things like that.

Edited May 12, 2015 by Sky_walker