***SPOILERS****
In the solar station, it is in the server room where you have to crawl through the tunnel and rearrange the fuses in the 2 separate rooms. In one of the rooms you want to rearrange the fuses so they are all blue and then a console will open up near the access tunnel. This will rotate the tunnel so that when you crawl through it you will end up in a room with the peng (among other things).