What is the difference between grid-tied and off-grid solar systems?

Grid-tied systems connect to the utility grid, allowing export of excess power and import when needed. They require grid-tie inverters with anti-islanding protection but need no batteries. Off-grid systems are independent, requiring battery storage for night/cloudy periods and careful sizing to meet all loads. Grid-tied is simpler, cheaper, and more efficient; off-grid provides complete independence but is more expensive. Hybrid systems combine grid connection with battery backup for power security.