The Generator in your Grow Op is responsible for running all of the equipment for growing the dankest buds and, as you can imagine, that takes a lot of power!
As you level up your grow lights and water pumps, as well as add more and more pots, you're naturally going to need more power. This is where your Generator comes in!
You'll need to upgrade the Generator as you progress through the game, and each upgrade will allow you access to more pots and water pump/light upgrades. It's definitely a key factor in getting the most out of your plants!