It all depends on the pumps and lights, like mentioned above (yes, the skimmer too but a pump drives the skimmer).
Heres an example: Most reefers choose one of two options for their main source of flow in a high flow tank (most commonly SPS). Powerheads, or Closed Loops pumps.
Im sure you know what a powerhead is. Point it, they don't suck up much power. A Tunze 6125 pushes 3,170 GPH at only 22W. That costs you as much as a desk lamp to run.
Now, a closed loop. The pros of using a closed loop set up (an external pump pulls water from the tank and return its straight back to the tank) are:
• Less showing in the tank
• Aesthetically pleasing
• Potentially cheaper than power heads.
But, these large pumps pull more power. A large ReeFlo pump can pull up to 1000+W, but an average is ~300W.
With the lights, well you could probably guess.
Metal Halide and T5 are cheaper to purchase, but more expensive to run and replace bulbs. LEDs are more expensive to purchase, but a lot cheeper to run, and will save in the long run. Its your choice.
Hope this helps.