How to design solar street light specification

How to design solar street light specification for your specific project based on different working condition?

“Energy saving and emission reduction” is a hot topic at present. With the aggravation of the energy crisis and the seriousness of environmental pollution, in order to have a sustainable environment, it is necessary to continuously develop and utilize new energy sources. Therefore, solar energy is a new energy source received public attention.

Compared with traditional street lights, solar street lights have the advantages of energy saving, environmental protection, aesthetics, low operating costs, and intelligent operation. Taking advantage of the natural environment, installing solar street light has very practical significance for strengthening energy conservation and emission reduction.

Solar Street Light Configuration

The main compositions of solar street lights including: solar panels, batteries, controllers, LED light sources, light poles. The price of solar street lights is calculated according to the specific parameters of the above components.

1. Calculate the current:
   Such as: 12V battery system; 2 pcs of 30W lamps, total output is 60W.
   Current I＝60W÷12V＝5A

2. Calculate the battery capacity:
   For example: the lighting time of (solar) street light is 7 hours per night (h)
   Need to meet the lighting needs of back up 5 rainy days (5 days plus the lighting of the night before the rainy day, let’s say total 6 days):
   Battery capacity =5A×7h×(5+1) days
   =5A×42h
   =210AH

In addition, in order to prevent the battery from overcharging and over-discharging, the battery is generally charged to about 95%; the remaining discharge is about 20%. So for a 210AH battery, the exact capacity is only about 75% in the application.

3. Peak demand (WP) of solar panels:
   The lighting time of street lamps needs to be 7 hours (h) per night;
   For example: the solar panel receives an average of 4.5 hours (h) of effective sunlight per day (Note: 4.5h is the sunshine coefficient of spefici area);
   For full charging purpose, at least 20% more power is demand.
   WP÷17.4V＝(5A×7h×120%)÷4.5h
   WP÷17.4V＝9.33A
   WP = 162 (W)

4. Simple formula for your design solar street light solution
   Solar battery module power = power * power consumption time / local peak sunshine time * loss coefficient (1.6-2.0)
   Battery capacity = power * power consumption time / system voltage * rainy days * system safety factor loss factor (1.6-2.0)