Efficient solar panel placing strategy

kerbal-space-program

I've built a Mun-orbiting science station to process all the experiments that I've gathered from surface and space around. Basically this is simple final-stage rocket with four 3×2 solar panels attached symmetrically around the lab.
When I got to actual processing, to the enormously slow data processing per se, a lack of solar power generation is added. Batteries are not a bottleneck of this design, as they don't charge to the max during sunny-time.

My small question is how much electricity do I need to keep a science lab up and running with full data & 2 scientist sciencing on it?

My bigger question is how to optimally place solar panels & which (3×2 or 1×6 or just cover the fuel tank with 1×1 panels?) so that they could be conveniently deployed and get the most suntime i.e. maximize electricity per panel per day and provide enough of so needed electricity for the lab?

Best Answer

TLDR:

The short answer is a Mobile Processing Lab uses approximately 5 units of electricity per second.

The long answer is a little more complex: Solar panel placement doesn't matter as much if your station is oriented in the right angle to catch maximum sunlight. What I mean is you can have all the solar panels in the world, but if they're on the shadow side of your station, they won't work.

Placement of solar panels

You should position your panels in a way that your orientation doesn't matter. I like to go with 4x symmetry and either the 1x6 or 2x3 panels, that way at least 2 panels are in some sun at all time. I prefer the 1x6 because they can stretch around from behind your station and still get some power.

This method of panel placement works in all orientations, whether side on to the sun, even if it's rotated or if it's pointed toward or away from the sun.

Supply of electricity

Your other problem is getting enough electricity to power your station. The 6 square solar panels (both 2x3 and 1x6) will supply 1.64 electricity units per second when pointed at the sun from Kerbin orbit (it increases as you get closer to the sun and decreases further away).

That means that you'll need two sets of four to get all the power you need.

OR... if you have unlocked the Gigantor XL solar panel, just one can supply 24 elec/second...

*not to scale (this is huge)

A final word on the mobile processing lab

If you want to keep your station powered - don't land it! On the surface night lasts... all night (5 hours on minmus), that means 5 hours on batteries. The Mun is tidally locked to Kerbin which means Mun's night is 3 Kerbin days - that's a long time without electricity. In orbit, night can be a single minute (or less depending on your altitude).

Related Solutions

How to use Jool to put a spacecraft into a solar polar orbit

So you're correct in using Jool for a gravitational slingshot into a high inclination, and you're also correct in assuming that you can only get about 40° from an encounter prior to switching the spheres of influence. Trying to set up burns prior to switching SoI is an exercise in futility. What you do want to do is set up your encounter so that you're coming in close to over a pole. 200m/s early (about a month out from switching SoI) can save a lot down the road.

Getting your trans-Joolian burn correct is actually one of the biggest factors for saving fuel. Not only do you minimize delta-V on the transfer burn, but you'll also minimize delta-V on the polar injection burn. You want to start your transfer about 65° after crossing the terminator into night when Jool is leading Kerbin by about 95°. When it comes to the phase angle, burning too early is really bad, as delta-V costs go up exponentially with the amount of time before optimal. Burning late isn't so bad, as costs go up much slower (quadratically maybe? Don't know for sure). This is a utility for determining optimal burn patterns.

So you've done your transfer burn, and you've done your final correction burn before switching SoI, and you're just waiting those last few seconds before that Jool orbit line changes from yellow to green. When that happens, you'll want to immediately plop down a maneuver node not too far in front of you. You're basically going to be doing a bunch of min-maxing to get your inclination into the high eighties. First, set your incoming inclination for best result inclination. Next, add about 500m/s of prograde velocity. You're doing this because you essentially have to kill something like 4000m/s of horizontal velocity and turn that into vertical. Next, reduce your periapse using the ground vector until optimal. Rinse and repeat, adding the most velocity in the prograde direction. Eventually, you'll get to a point where the inclination of the resulting orbit is correct, but the periapse will be in the sun, or the apoapse will be way out of the system. You're three options are to try and fix it now, try to fix it at Jool periapse, or (easily) fix it once you achieve polar orbit.

It's a tough operation, but with patience and experimentation, you should be able to get it every time.

Which communication method is most efficient

Note: With Version 1.2, the functionality of antennas was changed a lot and more antennas were added. This answer might not be very useful anymore.

With version 1.0, the antennas were rebalanced. But the stats listed on the construction screen seem to be misleading, because they have little relation to their actual performance.

As an experiment I tested transmitting the atmospheric analysis experiment with each antenna and measured the energy and time (without unfolding animation) it required.

Antenna     | Mass | Cost |Energy | Time
------------+------+------+-------+-----
16          | .005 | 300  | 1200  | 60s
DTS-M1      | .03  | 600  | 1200  | 35s
88-88       | .025 | 1100 | 2000  | 10s

As you can see, the antennas later in the tech tree have a higher transmission speed. The fastest antenna - the 88-88 - requires more energy than the other two to transmit the same results.

Often the limiting factor when transmitting is energy supply, not transmission speed. To really make use of the 88-88, you need more battery capacity and/or a lot more energy sources which means more mass to carry.

That means when timing is not a concern, the first antenna, the Communotron 16 is usually the optimal choice because it has the least mass and is the cheapest.

The only case where it might make sense to choose a faster antenna could be a probe which is planned to research the lower atmosphere of a planet but isn't equipped in any way to slow its descent and thus only has a limited time before it ~~crashes onto the surface~~ performs a lithobrake maneuver.

By the way: When you equip your craft with multiple antennas you can transmit multiple results in parallel which saves you a lot of time.