First of all, we need to know the composition of a 15W solar street lights.
Composition of 15W solar street light
1. light board (including light bead and aluminum base plate)
2. Solar panel (divided into polycrystalline silicon and monocrystalline silicon)
3. Lithium battery (divided into iron lithium and three yuan)
Second, calculate the power we want to use.
Self-use power calculation (formula: P power = u voltage I current)
1. Lighting power
2. Lighting time
3. Endurance in rainy days
Suppose that we need to use 30W solar street lights, and the lighting time is 8 hours a day, we can get:
30W * 8h = 240W (30W lights for 8 hours every day to get the consumed power)
In this way, we can get the capacity requirements of the battery pack that should be configured. Generally, 3.2V lithium iron single string / 3.7V three-element single string battery pack is used below 20W, 9.6V (lithium iron 3 string) / 12.8V(lithium iron 4 string) / 11.1V(three-element three-string) battery pack is used for 20-40w, and 24V battery pack is used above 50W (not much in this, because there are few used). We use 3 elements 11.1V lithium battery pack to calculate:
240W / 11.1V = 21.62a, even integer value is recommended, 11.1V/22a battery pack is required.
When the battery capacity comes out, calculate the generating power. Photovoltaic panels are usually 18V below 120W and 36V above 120W. Pay attention to the voltage. Generally, the average daily sunshine time is 3-5 hours (the sun at noon is full, and it is weak in the morning and afternoon). Baidu can find the local average sunshine time.
22A lithium battery / 5h (sunshine time) × 18V (solar voltage) = 80W (solar panel)
The light power is 30W, 22A11.1v lithium battery and 80W solar panel are required.