Christmas lights use quite a bit of electricity. The amount of electricity used depends on the type and number of lights, as well as how long they're left on. The average set of 100 lights can use anywhere from 4 to 20 watts of power per hour. So, if they're left on for 8 hours, that's between 32 and 160 watts of electricity used. If you have more lights or they're left on for longer, then the energy consumption will be even higher. It's important to be mindful of how many lights you use and how long you leave them on to