On-grid means your solar system is tied to your local utility’s GRID. This is what most residential homes will use because you are covered if your solar system under or over-produces in regard to your varying energy needs. All this means for you is that your utility system acts as your battery space. If you are producing more energy with your solar panels or system than you are using, the excess energy is sent to your grid’s power company, allowing you to build credit that you can cash out with at the end of the year, in a process called net metering. Being grid-tied is beneficial because you don’t have to buy an expensive battery back-up system to store any excess energy.