There are two main types of solar panel systems that you would mostly hear of – On-Grid (or Grid-Tied) solar power system and Off-Grid solar power system. While the former is connected to the local grid, the latter has no connection to the grid. As On-Grid solar power systems are connected to the local grid, they rely on the grid for power supply during the nighttime or during the days when the solar panels produce less energy than what’s required. And on days when the On-Grid solar power systems produce excess energy, the surplus gets passed to the local grid through a system known as Net Metering System. The surplus units transferred to the grid get offset later in the monthly bill. Off-Grid solar systems, on the other hand, have no connection to the grid and they rely on solar batteries for storing surplus energy produced by the solar panels and for using the stored energy when there’s a power deficit.