So I just found out there's a limit to the sun...

[technion]

I had a manoeuvre node with a two minute burn for a kerbin encounter, when I realised my solar panels had stopped working and I couldn't activate anything.

I guess the obvious thing to do is turn off SAS, recharge on the next lap, except it's a TEN YEAR wait to get back there!

[Johnno]

Yep, solar panels will generate more power on Moho than they will on Eeloo.

RTGs are handy so you don't have to rely on solar power.

[vexx32]

Aye, the solar panels get different output based on how close you are to the sun. It'd be interesting to know what the exact cutoff distance is.

[Kasuha]

Maybe you could check where your panels start working again and adjust the apoapsis to that height at PA. If you have enough fuel for that.

Another option is to try that correction at the point where your panels start working again. If you try to find optimal maneuver, it may not be that much worse than doing it at AP.

[technion]

Well FYI, cutoff seems to be ~200,000,000,000, although when it kicks in, it's still quite slow and I had to sit with SAS disabled for a bit before I could make a turn. Thanks Kasuha, I'll do just that, although it looks like it's going to be hours - top warp speed is terrible out here.

[SRV Ron]

Fixed panels will generate no power if parallel to the sunlight. If that is the case, you will have to wait until the ship gets orientated to the sun as it goes around its orbit. Otherwise, distance is figures in as to how much power a panel generates. While turning off SAS helps, probes always draw power. Expect dead batteries until your solar panels can generate enough power to wake up your ship

[SunJumper]

Also, why do you have such a large apoapsis?

[technion]

SunJumper, I just escaped Laythe and was in an orbit around the sun quite similar to Jool's when I left the computer for a bit. I came back and was floating through a Jool encounter that left me on the course in that screenshot.

[SpaceSphereOfDeath]

According to my voygigergerger probe the cut off is Approx 200Gm

EDIT: just thought of a hypothesis of why it happens, maybe that's the distance the sun gets unloaded from the game and there's just a sprite?

Edited October 28, 2013 by SpaceSphereOfDeath

[Rjhere]

According to my voygigergerger probe the cut off is Approx 200Gm

EDIT: just thought of a hypothesis of why it happens, maybe that's the distance the sun gets unloaded from the game and there's just a sprite?

That's an awesome name for a probe!

[Smidge204]

I noticed this myself sending probes out. I haven't taken any direct readings to determine if it's proper inverse-square law or not (probably is) but it's an appreciated attention to detail in a game already stuffed with details.

Anyone verify the dropoff rate for solar power yet? I might try to measure power gain at various Kerbol altitudes on my next trip out, just to see.

=Smidge=

[allmappedout]

I noticed this myself sending probes out. I haven't taken any direct readings to determine if it's proper inverse-square law or not (probably is) but it's an appreciated attention to detail in a game already stuffed with details.

Anyone verify the dropoff rate for solar power yet? I might try to measure power gain at various Kerbol altitudes on my next trip out, just to see.

=Smidge=

AFAIK, it's not inverse square, but I've done no experiments to prove this.

[Mr Shifty]

From the wiki:

Generated power will also decrease with increasing distance from Kerbol, but rather than following the real-life inverse-square law it experiences a spline curve of 3 piecewise cubics defined from 4 points:

Distance (m)	 Power        Comment
0                 10x	
13,599,840,256    1x          Kerbin's orbit
68,773,560,320    0.5x        Jool's semi-major axis
206,000,000,000   0x          Almost 3x Jool's orbit

[Nemoricus]

AFAIK, it's not inverse square, but I've done no experiments to prove this.

It's not, but out of curiosity, does anyone know why the developers chose to implement it this way?

[lazarus1024]

Oh. When was this added, because I never noticed it before?

I kind of wish it was closer to just the inverse-square law. That way for things Duna in, you can easily use solar panels. For stuff further out, you either have to go big with solar panels or switch to RTGs (supposing you want to do much).

That said, I'd guess for Jool and especially Eeloo you would want to either go dense with solar panels or just use RTGs.

This'll get more interesting as there are more things that require electrical power (and before that happens, please allow batteries to store more juice! They last an unrealistically short period of time for basically any load).

[Kerbart]

It's not, but out of curiosity, does anyone know why the developers chose to implement it this way?

I'll take a wild guess. First there was the level of solar power for Kerbin orbits. Then the inner planets were added. Inverse square works both ways, so to prevent solar panel performance from being absolutely ridiculous when venturing to the inner planets (a single panel would be enough for a gargantuan craft) performance was mapped to a fixed curve instead of the inverse square law. Which probably means that it's also a bit friendlier when going to the outside of the system.

[Smidge204]

From the wiki:

Well kiss mah grits! Interesting that they actually made it so complicated... Kerbart has a good point, especially considering the scale of the system as a whole is wonk'd for the sake of playability. Maybe inverse square wouldn't be a good fit after all!

=Smidge=

[phidauex]

It makes sense that the solution wouldn't be a true inverse square law, because photovoltaic cells don't respond linearly to irradiance - they have a linear range where their output is proportional to the irradiance, but at very low and very high levels they respond non-linearly. I'm not sure what you'd call the resulting curve, but it would be something of a "damped" inverse square law. Thermal effects will also start to affect panels - heat drops cell efficiency quickly, and without big heat-sinking a module near Moho would be suffering from large drops in efficiency (despite all the extra light).