Determine the configuration of battery panels and batteries, and control the cost of solar street lights

Determine the configuration of battery panels and batteries, and control the cost of solar street lights

We should know that before choosing solar street lights, we should make some preparations, such as where are solar street lights installed? What is the latitude and longitude? Road width geometry? How is the rainy weather? How long does it take to keep the lights on? Only in this way can we better determine some parameters of solar street lights, choose a good configuration, and bring a good light experience.

So in this process, how to determine the configuration parameters of solar street lights? Today, I will mainly look at how to determine the configuration of solar panels and batteries.

We can give an example to illustrate that a 12V 60W street lamp requires 7 hours of full load per night and 3 days of continuous cloudy and rainy days, and the local sunshine coefficient is 4 hours as an example.

 
1. Battery capacity

a. Calculate the current

Current=60W÷12V=5A

b. Calculate the battery capacity

First of all, we must understand that there are 3 consecutive days of rainy and cloudy days, but do not directly use this value for the subsequent calculations, but also add the lighting of the previous night, which is 4 days.

Storage battery=current×lighting time per night×days=5A×7h×4 days=140AH

However, it should be noted that 140AH is not the final capacity, and the problem of overcharge and overdischarge of the battery needs to be considered. In application, 140AH should be only about 70% to 85% of its true standard, and the actual working current of solar street lights will also be affected. Constant current source, ballast, line loss, etc., therefore, the current will increase by about 15% to 25% on the basis of 5A.
 
Therefore, considering this factor, the battery capacity should be recalculated, for this case.

The smallest battery capacity = 140AH ÷ 85% × 115% = 189AH

Maximum battery capacity=140AH÷70%×125%=250AH

2. Battery panel power

Before calculating the power of the solar panel, we should know that the solar panel is composed of solar cells. Generally, there are 36 cells connected in series. The voltage of a single cell is between 0.48 and 0.5V, regardless of the size of the solar cell. The voltage of the board itself is approximately between 17.3V and 18V. In addition, when calculating, at least relax the reserve of 20% of the battery board demand.

Battery panel power ÷ battery panel working voltage = (current × night lighting time × 120%) ÷ sunshine coefficient, then

Minimum battery panel power = (5A × 7h × 120%) ÷ 4h × 17.3V = 182W

Maximum battery panel power = (5A×7h×120%) ÷ 4h×18V=189W.
 
However, this is not the final battery panel power, because in the process of solar street light work, the line loss, the loss of the controller, and the power consumption of the ballast or constant current source are also different. Practical applications It is about 5% to 25%, so the smallest 182W and 189W are just theoretical values, which increase according to actual conditions.

The minimum actual power of the solar panel=182W×105%=191W

Maximum actual power of solar panel = 189W×125% = 236W

Therefore, in the case cited, the minimum battery capacity is 189 AH, and the maximum does not need to exceed 250 AH, and the battery panel must have at least 191W in terms of power and at most 236W.

When purchasing solar street lights, according to these calculation formulas, the lighting requirements are clarified, and various conditions are clarified, so that the configuration parameters of solar street lights can be better determined, and high-quality configuration can be completed at the lowest cost, bringing excellent The outdoor lighting experience.