How to configure a complete solar street light
How to calculate configuration of a solar street light? Firstly we need to figure out three questions below.
Now we will make every item clear, we also need to consider local working temperature, installation height, required brightness and different customers have their own demands, perhaps you can read my other articles at www.hansen-energy.com
For example, actual power 30W required, customer demand street lights on 10hours in evening and last 5 continuous rainy days.
Solution 1: Combination of half power and full power light on in evening(recommended)
What’s solution 1 meaning？ It is solar street light will be output in different brightness(power) in different time frame at night, controller adjust different current output to LED in different working time. For example, at night, larger flow of people from 7:00P.M to 11:00P.M, we adjust it as full power(30W) in the time frame and half power(15W) from 11:00PM to 3:00 AM, and adjust half power or full power from 4:00AM to 6:00 AM.(the time frame is just an example and factory can set different time frame and power based on customers’demands ). then we can calculate required power of solar panel according to this solution.
Required power value of selected solar street light
Confirming working hours in evening
Realize local sunshine hours(the equal sunshine hours in China is 4 hours)
Now we will make every item clear, we also need to consider local working temperature, installation height, required brightness and different customers have their own demands, perhaps you can read my other articles at www.hansen-energy.com
For example, actual power 30W required, customer demand street lights on 10hours in evening and last 5 continuous rainy days.
Solution 1: Combination of half power and full power light on in evening(recommended)
What’s solution 1 meaning？ It is solar street light will be output in different brightness(power) in different time frame at night, controller adjust different current output to LED in different working time. For example, at night, larger flow of people from 7:00P.M to 11:00P.M, we adjust it as full power(30W) in the time frame and half power(15W) from 11:00PM to 3:00 AM, and adjust half power or full power from 4:00AM to 6:00 AM.(the time frame is just an example and factory can set different time frame and power based on customers’demands ). then we can calculate required power of solar panel according to this solution.
Power(PV) is power for required solar panel and unit is Watt, and led source working hours unit is H, coefficient is 1.43, the value of 1.43 is ratio of solar kit peak voltage and system working voltage, fox example, a system with working voltage 12V for charging and discharging, and its peak voltage of solar kits can reach 17V~17.5V, when system working voltage is 24V and peak voltage is 34V~34.5V(it seems like a 4.2V charger is not able to charge for system of working voltage 12V, so charging voltage voltage requires higher than system voltage). peak sunshine hour is H, two coefficient are 0.85, which are battery coulombic efficiency and solar kit attenuation losses, dust cover and other factors.
Fox example LED power is 30W, working hours 10hours and local peak sunshine hours is 4Hours, then the power for solar panel should be:
Specific solar panel power is decided by solar kit specification, we can choose 125W.
We will calculate battery capacity since we have solar panel power.
The calculation of battery capacity, we need to realize local rainy days situation and get what kind of battery we will use(LiFeO4 is most choice) and lasting days, as told customer require 5 continuous rainy days, the calculation process below:
Battery voltage unit is AH, load power unit is Watt, Working hour per day is H, storage days is D(day), and Depth of Discharging(DoD) is based on different kind of battery, we can set it as 0.7, system voltage unit is Volt. Then LED source is 30W, working hour per day is 10hours(8hours full power in total), storage days is 5 days.
Above we said our solution is combination of full power and half power, so actual full power hours per day is 8H, so the battery we need is 12V 175AH, this kind solution is a electricity saving solution and many factories use the solution.
Solution 2: Full power in whole (not recommended)
This kind of solution requires the light output is 30W in whole night(10hours) from 7:00pm to 6:00am, then required solar panel power and battery capacity will be larger and leads to cost increased.In solution 2, the solar panel power should be,
In Solution 2, the required battery capacity should be,
According to above calculation result, we can see the solar panel power is 148W in solution 2, actually we need to choose 18V150W panel and battery capacity is about 12V 220AH, then the cost will be increasing 20% around.
To sum up, I believe you have a rough realization on calculation, but nowadays there are many suppliers overstate power value and battery capacity and etc. You can see my post http://www.hansen-energy.com/new/Solar-Street-Light-K-SeriesAll-in-Two.html
Thank you for your reading!