Field study on operational performance and economics of lithium-polymer and lead-acid battery systems for consumer load management

This paper presents long-term field test results of lithium-polymer and advanced lead-acid battery systems for consumer load management. The battery systems aimed to minimize electricity bills of an industrial consumer by shifting its load to lower priced time-zones and regulating its peak. Annual and daily peak reduction effects and operating revenues are examined under a time-of-use tariff and battery promotional incentive. Capacity degradations of the batteries are calculated to estimate the actual lifetime. Based on actually earned revenue during the field test and predicted service life for the each type of the batteries, total expected revenue per unit installation capacity is estimated and compared with investment cost per capacity to perform the economics of the tested battery systems for consumer load. This analysis found that the profitability cannot be assured under the considered time-of-use pricing alone but can be expected when adequate incentive is provided. It is also revealed that the batteries in real use conditions lose their capacity considerably quicker than suggested by manufacturers. Therefore, it is recommended to consider actual fading pattern of the battery for accurate economic evaluation at the design stage and to reflect the battery degrading cost into the charge-discharge scheduling model to optimize operating revenue.