Without a connection to the utility grid, batteries are essential to balance periods of excess production and excess demand. In addition to batteries, these systems almost in all cases, will require supplemental power such as Generator. This is to protect the batteries against shortfalls of power when the solar system is under-producing and the batteries are discharged, especially in Winter months and or when there is not enough Sunlight available.
Off-grid solar systems differ from grid-tied systems in the sense that solar is the primary source of electricity to the structure. This requires some adjustment of when and how the power is used to live within the design of the system.
For example, the battery banks can store enough electricity for a household for 1 to 3 days (or more, depending on the battery size). If there is a longer stretch of cloudy days and the sun energy is running low, a back-up generator would need to provide power. For these reasons, off-grid solar systems are a primitive or “remote-only” alternative to more common solar setups.