The Central Power Hub (CPH) is your main power generator at the start game. It has Solar Panels, and can burn fuels to generate power. Unfortunately it can only hold one fuel source at a time. In the tutorial of the game you will set up a basic fuel system for your CPH using some Coal Ore that is near, This will run out over time and you will need to find more, this can be automated the same way from a distance to keep a constant supply of Fuel to the CPH.
It can hold 2,000 Power as is sufficient enough to handle your basic build at the start of the game. This is your main base central core and must be protected at all times, any mobs that appear will go directly for your CPH and avoid any other structures you have built. Protect it!
You cannot build directly above the CPH. For the 1st 2 block height above the CPH there is a 3x3 radius, after the 1st 2 blocks the radius increases to 5x5.