Investigation of lithium-ion battery cycling in a grid-tied rooftop PV system through accelerated testing

Residential battery energy storage is expected to add considerable value to urban rooftop PV systems under Time-of-Use (TOU) retail electricity tariff structures. Lithium ion batteries in particular could provide an efficient means of shaving residential seasonal evening peak demand. In this paper, daily cycling behavior of a 73 Watt-hour (Wh) prototype lithium ion battery is analyzed on an accelerated basis to study its daily cycling characteristics as in a PV coupled system. Summer specific cycling of storage battery is conducted with a variable resistive load bank and a PWM controlled DC power supply substituting solar array. Due to the accelerated nature of testing, four round trips were possible in a single day. The battery was able to supply 1.21 kWh of monthly and 40 Wh of daily summer load with 45 Wh average input in each charging cycle. Economic and system indices driving monthly electricity charge savings are also addressed.