On-grid systems are the most common type of solar PV system for a home or industry. They are connected to the electrical grid, and allow the alternative and practically simultaneous use of solar energy as well as electricity from the grid. This type of systems do not need to produce 100% of the electricty demand for a home or business.
As we know electricity has to be spent in real time. However, the over-generated energy can be temporarily stored as other forms of energy (e.g. chemical energy) in batteries, as this usually requires a solid money investment and typically comes with significant electricity losses.