Coping with an ever-growing telecom network becomes more challenging, especially in places where the electrical grid is unreliable. Operators looking to extend back-up power capability must increase energy storage capacity, pushing today's mainstream technologies beyond their limits.

Most back-up power systems used in telecom sites today rely on Valve Regulated Lead-Acid (VRLA) battery banks, which are costly to maintain and need replacements typically every 3 years. These battery banks are also typically heavy, bulky, and are prone to self-discharge.

Critical back-up time required at telecom sites ranges from 4 to 8 hours. Many telecom operators oversize their VRLA battery banks as much as 300% (up to 24 hours back-up time) to cater for unexpected long-duration outages. This solution is costly as all the battery banks need to be replaced at the end of their lifetime.

Remote off-grid telecom sites also integrate photovoltaic (PV) solar panels used to recharge the VRLA battery banks during the day. At night, the sites rely completely on these battery banks for power. Many telecom operators currently oversize their VRLA battery banks to cater for unexpected decreases in solar exposure, such as poor weather during several days. As a result, it is not uncommon for PV integrated off-grid telecom sites to have reserve battery banks that offer up to 3-5 days of run-time.