Firstly, the current is calculated.
Such as: 12V battery system; 30W lamp 2, a total of 60 watts.
Current = 60W_12V = 5A
Second: Calculate the battery capacity requirements:
For example, the cumulative lighting time of street lamps per night should be 7 hours (h) of full load.
(If it opens at 8:00 p.m., closes Road 1 at 11:30 p.m., opens Road 2 at 4:30 a.m., and closes at 5:30 a.m.)
It is necessary to meet the lighting requirement of 5 consecutive rainy days. (5 days plus overnight lighting on rainy day for 6 days)
Battery=5A*7h*5+1 days=5A*42h=210AH
In addition, in order to prevent the battery from overcharging and overdischarging, the battery is generally charged to about 90%, and the remaining discharging is about 20%. So [FS: PAGE] 210AH is only about 70% of the real standard in application.
Third: Calculate the peak demand of battery panel (WP):
The cumulative lighting time of street lamps per night is 7 hours (h).
: The average daily effective illumination time for the panels is 4.5 hours (h); at least the 20% reserve for the requirements of the panels should be relaxed.
WP_17.4V=(5A*7h*120%) and_4.5h
WP_17.4V=9.33
WP = 162 (W)
: The daily sunshine time of 4.5 hours is the sunshine coefficient near the middle and lower reaches of the Yangtze River. The upper and middle reaches of the Yangtze River are generally 5 hours.
In addition, in the solar street lamp module, line loss, controller loss, and power consumption of ballast or constant current source are different, which may be about 5% - 25% in practical application. So 162W is only a theoretical value, which needs to be increased according to the actual situation.
