4 Major Differences Between Off-Grid and Grid-Tie Solar
1. Grid-tie/on-grid inverters do not function with batteries meaning there is no way to store solar energy for later use — you use as you make solar energy (when there is sun) and go back to grid when sun is not available, whereas off-grid system comes with a battery bank, where excess solar energy is stored in batteries for future use.
2. Grid-tie systems are tied to the grid which means when the grid fails, and then grid-tie inverter will stop working. Off-grid solar system will work irrespective of grid availability as it is supplying the electricity either directly through solar or from the batteries.
3. With grid-tie systems you can sell excess solar power that you make back to the grid/electricity company which is not possible with off-grid systems. In the case of off-grid systems, the excess solar power, which gets left after charging the batteries and running the load, cannot be used.
4. Grid-tie systems should used in areas with good grid supply and for establishments where the operational hours are during the day such as schools, colleges and other businesses. If you live in a place where the state offers an attractive net metering policy then on-grid solar makes good financial sense for you. Off-grid systems should be installed where grid supply is unreliable such as farmhouses in remote places, villages etc.