Solar street light power system design and calculation

We usually analyze various factors affecting the solar street light power system firstly, and then calculate the actual solar street light power system according to the situation. When designing the solar street lamp power system, we generally calculate the daily power generation, storage, and power storage according to the power consumption of the lamp, and finally provide a scientific and reasonable configuration scheme for the user.

Solar street light design calculation

The factors that affect the power system.

Width and lanes of the road

When we know the condition of the road, we will know how to determine the pole height and pole distance.

Requirement of lighting

we need to know the requirement of lighting, like ground lux level, then we can calculate the power assumption of LED light, which is mutually determined with the lamp pole.

Operation Hours per day

How many lighting hours per day, whether the user needs half power after midnight?

Sunshine conditions

It depends on the sunshine conditions in the application area, which mainly depends on the annual average sunshine radiation value and the lowest peak sunshine in winter

Average continuous rainy days in this area.

Other conditions, like the highest or lowest environment temperature.

With these conditions, a scientific and reasonable solar power system can be designed.

Street light power consumption calculation

Calculation of battery configuration of the solar street lamp

1： First, calculate the current:

For example 12V battery system; two 30W lamps, 60 watts in total.

Current = 60W ÷ 12V = 5 A

2： Calculate the battery capacity demand:

For example the cumulative lighting time of street lamp every night needs to be 7 hours (H) with full load;

(for example, open at 8:00 p.m., close 1 road at 11:30 p.m., open 2 roads at 4:30 a.m., and close at 5:30 a.m.)

It needs to meet the lighting requirements of 5 consecutive rainy days. (5 days plus the night before the rainy day, 6 days in total)

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

In addition, LUXMAN Solar lighting reminds you that in order to prevent overcharge and over-discharge of the battery, the battery is generally charged to about 90% and the discharge remains about 20%. So 210ah is only about 70% of the real standard in the application.

Calculation of solar street lamp solar panel

3： Calculate the peak demand (WP) of the solar panel

The cumulative lighting time of the street lamp every night needs to be 7 hours (H);

★: the average daily effective illumination time of the solar panel is 4.5 hours (H);

At least 20% of the reserved amount for the solar panel needs to be reserved.

WP÷17.4V ＝ （5A × 7h × 120％）÷ 4.5h

WP÷17.4V ＝ 9.33

WP ＝ 162（W）

★: the daily illumination time of 4.5H is the sunshine coefficient near the middle and lower reaches of the Yangtze River.

In addition, in the solar street lamp module, the line loss, controller loss, the power consumption of sensors, and constant current source are different, which may be about 5% – 25% in practical application. So 162w is only the theoretical value, which needs to be increased according to the actual situation

Related article:

https://luxmanlight.com/how-to-choose-batteries-for-your-solar-street-light-project/