The Power Plant is a large man-made area presumably used to power the other buildings on Isle V3. It has massive power-lines that run underground, so it can be theorized that the power plant powers every building on the island through underground cables. It can be assumed that it uses some form of hydroelectricity for power, due to its closeness to the ocean.
It is one of the most isolated buildings in the map, the closest water source is at the Port.