If you are currently using grid power, grid-tied PV is the most efficient method of turning the sun's energy into electricity. This is mainly because these systems do not require any batteries. Grid-tie inverters convert the solar DC into AC power, and match the frequency of the grid (hence the name, grid-tied). These systems can be used in any size, from a single panel to large solar farms. The systems can either offset energy and costs directly, or be metered separately on a feed-in tariff program.