ZEMCH 2019 International Conference Proceedings April.2020 | Page 440
charges the battery only with PV power. Mode 2 supplies PV power to the load first and charges the
battery with PV and grid power. In mode 3, the battery is preferentially charged with PV power, and
only the PV power is supplied. Mode 4 preferentially charges the battery with PV power and then with
PV and grid power.
Table 1. Operation modes of BESS.
Operation Mode
Mode 1
Mode 2
Mode 3
Mode 4
PV Power Supply Priority
Load
Load
Battery
Battery
Battery Charge Source
PV only
PV & Grid
PV only
PV & Grid
4. Experiment Results
The power data per day were analyzed for each operation mode of BESS. The experiment lasted
about 3 months from August 21, 2019 to November 08, 2019. The experiment was conducted on all days
except rainy days and days the apparatus were checked. This paper representatively describes the
experimental dates that showed the characteristics of the modes. Figure 3 shows the graph of time
variations of the daily PV, battery, grid and load power, battery voltage, and battery capacity (SOC). In
this experiment, the connection load was an electric fan with a power consumption of 260 W, but it
actually consumed 200 W. For reference, the PV power differed between day to day due to weather
effects.
Under mode 1, charging started at 06:18 and was completed at 09:54 on August 23, 2019. The
power was fully discharged about 10 h after the battery began to discharge. The discharge power was
1.854 kWh (discharge peak power of 0.199 kW), and the load power at this time was 2.037 kWh. An
intermittent discharge occurred between 15 and 17 oʹclock, but the start and end times of
(a) Mode 1 (August 23–24, 2019) (c) Mode 3 (November 05–06, 2019)
(b) Mode 2 (August 27–28, 2019) (d) Mode 4 (September 17–18, 2019)
Figure 3. Performance characteristics of BESS prototype with veranda PV.
(a) Mode 1; (b) Mode 2; (c) Mode 3; (d) Mode 4;
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ZEMCH 2019 International Conference l Seoul, Korea