The ampere-hours removed from a fully charged cell or battery, expressed as a percentage of rated capacity.

For example, the removal of 25 ampere-hours from a fully charged 100 ampere-hours rated cell results in a 25 percent depth of discharge.

Under certain conditions, such as discharge rates lower than that used to rate the cell, depth of discharge can exceed 100 percent.

An adjustment factor used in some system sizing procedures which "allows" the battery to be gradually discharged over a 30-90 day period of poor solar insolation.

This factor results in a slightly smaller photovoltaic array.