Every building on the Island needs a power supply.

Note, the more buildings you have, the more electric power is needed. Thus, you will get notifications from time to time, that you need more electricity to place a new building.
Build eco-friendly power plants, generators, and windmills — all which you can find in the Service tab in the store. This way, you'll never face a power shortage.

You can also use special accessories that reduce energy consumption in a building or increase energy production from power plants.