Since solar panels generate electricity only from sunlight, you need a way to store energy. Although batteries can be used for storage, the simplest (and cheapest) solution for most people is to maintain a connection to the grid.

If your solar panels generate more energy than you use - when you're at work, on vacation or just not running many devices - excess power will flow back to the grid. In many places, utility companies offer a program called “net metering” that compensates for the extra power you generate.

At night, or whenever you need extra power, you will pull it out of the grid. With a grid-connected system, you will never have to worry if the power you need is greater than the power required by your solar system. You can also choose to use only solar energy to provide a partial average electricity bill and then use the grid.