How to choose solar street lamp
We should know that before choosing the solar street lamp, we should do some preparatory work, such as where is the solar street lamp installed? What are the latitude and longitude? What's the width? What about rainy weather? How long do you need to keep the lights on? In this way, we can better determine some parameters of solar street lamps, choose the right configuration, and bring good lamp experience.
So in this process, how to determine the configuration parameters of solar street lamps? Today we will look at how to determine the configuration of solar panels and batteries.
We can take an example to illustrate that for a street lamp of 60W with 12V, the cumulative lighting time of each night needs to be fully loaded for 7 hours and 3 consecutive cloudy and rainy days, and the local sunshine coefficient is 4 hours.
One, battery capacity
A. calculate the current
Present current = 60 w 12 v = 5 a
B. Calculate the battery capacity
First of all, we should understand that it will be cloudy and rainy for 3 consecutive days, but we should not directly use this number for the following calculation, and we should also add the previous night's lighting, which is 4 days.
Battery = current × lighting duration × days per night =5A×7h×4 days =140AH
But to pay attention to the capacity of 140 ah is not finalized, also need to consider to the problem of battery charge discharge, 140 ah should only in the application of the real standard of 70% ~ 85%, and actual working current of the solar street lamps will be affected by the constant current source, ballast and line loss, therefore, the current on the basis of 5 a also increases 15% ~ 25%.
Therefore, considering this factor, the battery capacity should also be recalculated, for this case.
Minimum battery capacity =140AH÷85%×115%=189AH
Maximum battery capacity =140AH÷70%×125%=250AH
Computing power panels, we should know that solar panels composed of cells, generally speaking, there are 36 pieces of batteries in series, single block of cells, regardless of size, about between 0.48 ~ 0.5 V voltage, voltage of solar panels itself probably between 17.3 V ~ 18 V, in addition, calculation, ease demand for panels at least 20% of the reserve amount.
Panel power ÷ panel working voltage = (current × lighting duration per night ×120%) ÷ sunshine coefficient, then
Minimum power of the panel = (5A×7h×120%) ÷4h× 17.3v =182W
The maximum power of the panel = (5A×7h×120%) ÷4h×18V=189W
However, this is not the ultimate power panels, because in the process of solar street lights work, but also to the line loss, the loss of the controller, and power consumption of the ballast or constant current source is also different, about 5% ~ 25% in the actual application, so a minimum of 182 w and 189 w is only a theoretical value, according to the actual situation is also increased.
The actual power of the panel is the minimum =182W×105%=191W
The maximum actual power of the panel =189W×125%=236W
Therefore, in the case cited, the battery capacity should be at least 189AH, and the maximum should not exceed 250AH, while the panel power should be at least 191W, and at most 236W.
In the purchase of solar street lamps, according to these calculation formulas, the lighting requirements are clarified and various conditions are clarified, so as to better determine the configuration parameters of solar street lamps, complete the high-quality configuration at the minimum cost, and bring excellent outdoor lighting experience.