Planned operating strategies can extend life of solar batteries

A commercial collaboration with IBM Research Australia

Batteries that store renewably sourced electricity are set to change the way people access and pay for electricity, with Australia at the vanguard of adoption.

About half of the 1.5 million Australian households with solar panels are expected to add batteries to their systems in coming years to counter a drop in payments they receive for energy contributed to the national power grid.

With such a massive shift underway, agile technology companies such as IBM Research Australia have perceived that both the battery industry and incumbent energy providers will face technical challenges and have research underway to provide solutions.

A key issue is how decisions about the way the batteries are used impact on the batteries’ lifetime and, therefore, their cost.

The implications of these decisions can now be explored using optimisation methods developed in part by Khalid Abdulla, a PhD student at the University of Melbourne’s Department of Mechanical Engineering. His research was conducted in conjunction with an internship program to work on the problem with the IBM Research Australia team.

The life of a lithium battery in a residential setting can range from about three to eleven years depending on how it is operated.

The lifetime can be extended by operating about the middle range of battery states of charge. That might mean cycling the battery between 70 and 30 per cent full, rather than completely discharging or fully charging them.

Also, slow rates of movement between high and low states of charge (operating the battery at lower currents) further reduce battery degradation.

Mr Abdulla’s research found that optimising a battery’s operation to reduce household electricity bills, while ignoring degradation, results in a short battery life. A 50 to 100 per cent greater lifetime value is possible with strategies that account for battery degradation in the optimisation.