Storage technologies are not only defined by the storage medium, but also by the type of application and the duration of time over which the stored energy is used. The typical time durations and applications are generalized as follows:
|Duration of Energy Storage Capacity at Rated Load of Storage Device
|Extremely short duration (1-10 seconds)
||Power quality: provide critical load ride-through during voltage sags and shorter momentary interruptions.
|Short duration (10-300 seconds)
||Power quality: provide critical load ride-through during longer voltage sags and momentary interruptions. Allow time for alternative power feeds and back-up generators to be energized.
|Moderate duration (5-60 minutes)
||Power quality/service reliability: all previously described benefits, plus allow for ride-through during longer-duration power interruptions.
|Longer duration (1-4 hours)
||Power quality/service reliability/ some limited DER applications: all previously described power quality benefits plus some limited load-leveling/peak-shaving capabilities.
|Very long duration (4 hours up to several days)
||Distributed storage and generation - load-leveling, peak-shaving. Storage for stand-alone PV or wind systems.