1： First, calculate the current:

Example: 12V battery system; Two 30W lamps, totaling 60 watts.

Current=60W ÷ 12V=5A

2： Calculate the battery capacity requirement:

For example, the cumulative illumination time of street lamps at night needs to be 7 hours (h) at full load;

(For example, opening at 8:00 pm, closing 1 channel at 11:30 pm, opening 2 channels at 4:30 am, closing at 5:30 am)

Need to meet the lighting needs for 5 consecutive rainy days. (5 days plus overnight lighting before cloudy or rainy days, totaling 6 days)

Battery=5A × 7h × (5+1) days=5A × 42h=210AH

In addition, to prevent overcharging and discharging of the battery, the battery is generally charged to around 90%; Leave about 20% of the discharge residue. So [FS: PAGE] 210AH is only about 70% of the true standard in applications.

3： Calculate the peak demand (WP) for the battery panel:

The cumulative illumination time of street lamps per night needs to be 7 hours (h);

★: The average daily effective light exposure time for battery panels is 4.5 hours (h); Relax the reserve requirement for battery panels by at least 20%.

WP ÷ 17.4V=(5A × 7h × 120% ÷ 4.5h

WP ÷ 17.4V=9.33

WP=162 (W)

★: 4.5 hours of daily light exposure refers to the sunshine coefficient near the middle and lower reaches of the Yangtze River. The middle and upper reaches of the Yangtze River generally last for 5 hours.