By the end of this year, and for the first time in history, more people are going to store energy in personal residential batteries that are tied to the electrical grid. This represents a 57% increase in total residential battery system sales. Grid-tied home batteries offer users a more reliable source of power because they are independent of fluctuations in renewable energy generation, such as low solar output on cloudy days. Energy generated by turbines on a windy day, for example, could be stored in a battery for use when there is little to no wind.