Marginal Costs of Battery System Operation in Energy Arbitrage Based on Energy Losses and Cell Degradation

Optimal control of a battery energy storage system for energy arbitrage strongly depends on the marginal costs of operation. A cost function considering energy conversion losses and cycle-induced capacity losses is defined to calculate the marginal costs as a function of system power and power flow direction. The results are evaluated and reveal increased costs due to energy losses at low power operation, as well as increased costs due to capacity loss costs during charge operation at high power. The marginal cost function is evaluated for an optimal system control in an energy arbitrage scenario with variable electricity prices. Here, results show that for low price variation the optimized power control aims for minimized marginal costs. At high price variation, that strongly exceeds marginal costs, the optimum operation according to the best prices is the most profitable control. Finally, a discussion on the inclusion of the cycle-induced capacity losses is presented.