For only a little extra material, you too can have solar power for your deep sea base ... no longer need for puny Bioreactors or expensive Nuclear Reactors.
How do you do it you ask? I am glad you did because I will tell you.

Because ...

1. ... power is distributed trough all off the base, even parts that aren't physically attached!
   
2. ... the Multipurpose Room has one more special exploit! (more to that later)
   
3. ... system doesn't check if parts are "physically" attached! And even if it would does it ...
   
4. ... It doesn't check if later the chain is broken!

We all understand that this is a way to attach an I Compartment to (in this case) the Multipurpose Room (but base in general):

But this does the same!

This will be a full fledged part of your base, if you build it.
Though you still will need an (extra) entrance to it.

1. The stuff to build your base. (aside from what we do in this guide)
   
2. Seaglider (lets face it ... you need to move around fast)
   
3. Seamoth (because you don't want to drown)
   
4. Habitat Builder tool
   
5. 10 additional Titanium
   
6. 2 additional Glass
   
7. at least 1Storage Module for Seamoth for storing building material

(additional to the needed ones)

1. Seamoth Solar Charger
   
2. 2 additional Titanium and 2 additional Quartz for each Solar Panel you want to build
   
3. Ultra Glide Fins
   
4. Ultra High Capacity Tank
   
5. ability to build the Multipurpose Room
   
6. Cyclops
   
7. spare Batteries

Don't forget to move your Seamoth along (always a bit above where you build) to have access to your storage and air.

1. Pick your building site. e.g.
   
   
2. Build your first Multipurpose Room as normal. Maybe with Foundations underneath, if you want to.
   You can also build an airlock into it at that point. (But not needed, base isn't functional anyway at that time)
   
3. Put all Titanium in your Seamoth Storage Module. (other building material doesn't matter)
   
4. Place a ghost not directly above your base but with one space.
   Don't
   
   Do instead
   
   
5. Because you have no materials for it it will show up but not being build (and not using power from your tool)
   and look like this:
   
   
6. Repeat from step 4 till it will let you no longer place ghosts
   
   
   
7. Now take out exact 6 Titanium out of your Seamoth and then finish building the top module
   
   
8. Remove all ghosts
   
   
9. Now you can start over (from step 4) on top of top most Multipurpose Room till you reach step 6 again.
   But instead of taking out more titanium deconstruct the temporary (now free floating) Multipurpose Room in middle and use that to finalize the top one.
   
   
10. Rinse and repeat the last step till you reach the surface
    
    
11. Now place a Foundation next to your top most Multipurpose Room
    (Room might have to be finished to do so)
    
    
12. Now you can deconstruct the top most Multipurpose Room for reusing titanium, and finish the Foundation with it.
    
13. If this foundation is above water ... you can skip to step 17
    It is not above water if it looks like this: (avatar is still swimming)
    
    
14. Place the next ghost one step higher (also an Foundation)
    
    
15. Deconstruct the Foundation which is still under water.
    
16. Finish the top Platform
    
17. Now build an I Compartment (also known as Basic Compartment) facing towards the platform (slightly above it).
    
    
18. Now take out the rest of Titanium out of your Seamoth (and the Glass and the Quartz if you don't have them already in your inventory)
    
19. Add a Hatch at the bottom
    
20. Climb in through that Hatch.
    
    
21. And build another Hatch facing the Foundation from the inside.
    
22. After exiting the last Hatch you now should stand on the Foundation (Only way to get onto the Foundation.)
    
    
23. Now you can build as many Solar Panels as you like / have the material for
    But one is enough to power the basic functions of your base. (and above water it works better than below)
    

The base is now powered:

All of it.

• I don't have the Multipurpose Room / I don't like the Multipurpose Room.
  Is there a other way?
  
  Yes, there is. But that way takes more time, materials, and energy from the build tool.You can use most non glass Compartments (Basic /I, T, and X) which have an attachment point on top.Which you can use to build Vertical Connectors on top.
  But going that route you need to finish all parts you want to build on top of.And that takes more time and energy for construction and deconstruction (build one, place ghost on top, deconstruct below, finish building ghost, place ghost on top, and so on and so forth)
  And you get less height per step.
• I can't reach the Hatch (to get on the top Foundation)
  
  Swim upwards with full speed. That will make you jump out of the water a little. That most likely will help you reach it.
• I can't build the Foundation
  
  The Foundation can only be build if there is no part of the base directly below it ... no matter how deep below.Check if you have build something already there and work around it if need be.(But leave at least one part of your base on the sea floor)

http://creativecommons.org/licenses/by-nc-nd/4.0/
This guide "[exploit] Münchhausen Base (solar power for deep sea bases) (picture heavy)" in Steam by BiZZ Keryear is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.[creativecommons.org]
If you want use this work you have to link back to here, mention my username, and aren't allowed to add commercials (or earn money in any other way).