Backup Batteries

Batteries can be a cost-effective backup solution for short duration outages typically less than three hours. The graph below shows the probability of an outage based on the duration of the outage, and the majority of outages are relatively short. While the average outage duration might be several hours, this is skewed by the rare probability of such long outages.

A three-hour battery is likely to provide sufficient backup for about 50% of outage events. For many organizations this is sufficient because longer outages typically are associated with extreme weather events that force facility closures anyway. Obviously, battery backup would not be appropriate for operations that must keep operating for long periods of time, such as hospitals, nursing homes, food storage, and emergency centers – These require fossil-fueled backup generators. 

The combination of a battery and a small fossil fuel backup generator might be the most economic and practical solution for your organization.  The battery can handle short outages, and the fossil-fuel backup generator can support critical operations such as refrigerators, freezers, and safety equipment for extended periods. This combination of covering the entire load for a couple of hours and only the critical equipment for long periods represents the way most organizations operate.