On Grid with Battery Back-up System
Grid tied with battery backup system. To decrease your dependence on the grid even further, you can add a battery to the system to collect excess solar energy for use when light is low. You’re still tied to the grid as a secondary power source, but rather than feeding your surplus into the grid, you store it up for your own later use.
Off Grid Battery Stored System
Off Grid Photovoltaic Systems. These are not tied to the grid as a secondary power source. This is the extreme green alternative for those who want to eschew commercially generated electricity altogether. Off-grid systems are most useful for summer applications (when there’s more sun) and/or for places that have no access to the main grid. Recreational vehicles and remote cottages are prime candidates for this type of system. For practical purposes, especially for primary residences, you would want to have a generator for back-up power in cloudy weather or periods of high energy demand.