After the photons are transformed into electricity, the panels direct this energy to power the home. Some homes, those independent of the utility grid, must rely on battery storage to store energy, yet they may also have to rely on backup generators when there is too much demand on the size of the system. Many people use solar in tandem with the utility companies so that they have a convenient back-up during fluctuating periods of energy. This net metering partnership is a bit involved, but it has also been evolving to become more effective as more and more people choose solar to provide the bulk of electricity to power their homes.