I have answered this question in this post related to the Table of Shewbread, but I would like to elaborate a little bit more as I think it is very important.
The Golden Lampstand (The Menorah) was placed by the Southern Wall of the Tent of the Mishkan because, just like the Table, it had everything to do with the astronomical orientation of the Tabernacle.
First of all, when placement of the Lampstand is described, two different expressions are used:
- In Exodus 26:35, expression תימנה [têmānâ] is used, usually translated directly as "southward/ toward the south"
- But in Exodus 40:24, expression נגבה [neḡəbâ] is used, which is usually translated as "Negev ward /toward the Negev", but sometimes (i.e Gen. 12:9) as "toward the south-rim".
Therefore, you can rely on these interesting facts and on the diagrams below to get an idea why the Menorah was by the Southern wall of the Tent of the Tabernacle:
Here is a Sun Path diagram from this web site:
And here is another Sun Path diagram from this web site::
And one more Sun Path diagram from this web site:
this applet) for the Tabernacle if it had been located in Shiloh, Israel:
So as you can see, the Menorah (Lampstand) was located by the Southern wall of the Tent of the Tabernacle because it would essentially "mimic" the location of the Sun, REGARDLESS of where the Tabernacle would have been located.
Therefore, the Menorah would shine (just like the Sun) from the Southern wall of the Tent upon the Northern Wall (where the Table stood).
Here is a rendering to give you a better perspective on how these two artefacts were positioned relative to each other:
You can also check out the links below for extensive information and tools regarding the Sun Path and Position details: