Systems and methods for determining degradation of batteries

A system for estimating battery degradation of a battery energy storage system (BESS), comprising:

• a controller comprising one or more processing modules and one or more non-transitory memory storage modules storing computing instructions which when executed by the one or more processing modules is configured to:
• (a) execute an iterative process over a pre-defined time period, wherein the pre-defined time period is divided into a plurality of iterations, wherein each iteration of the plurality of iterations comprises:
• (1) determine an average temperature of the BESS for a current iteration of the plurality of iterations by inputting the following into an average temperature look-up table (LUT):
• a state of health (SOH) of the BESS for the current iteration and a charge rate of the BESS for the current iteration;
• and
• (2) input the determined average temperature into a set of cell degradation equations to determine a SOH of the BESS for a next iteration of the plurality of iterations.