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# Power calculation of Outdoor Solar Street lights

2021-07-14 10:04:01 Outdoor solar street light design

Outdoor solar street lights are composed of solar panels (including brackets), lamp holders, control boxes (with controllers and batteries, etc.), and light pole foundations. Solar street lights are generally separate power supply systems and are not connected to the power supply network of conventional street lights. There are three main types of solar street light systems: 12V, 3.2V, and 3.7V.

Solar street light battery selection
1. Type of outdoor solar street light battery

Solar cells convert solar energy into electricity. There are two more practical ones, such as monocrystalline silicon and polycrystalline silicon.
1) The performance parameters of monocrystalline silicon solar batteries are relatively stable, suitable for use in places where the average sunshine time exceeds 4 hours;
2) Polysilicon solar panels are suitable for use in places where the sunshine time is less than 4 hours;

2. Working voltage of the outdoor solar street light battery
The working voltage of the solar street light battery is about 1.5 times of the battery voltage to ensure the normal charging of the lithium battery. For example, 5V～6V is needed to charge the 3.2 battery.
Solar street light battery requires 15-18V solar battery to charge 12V lithium battery. To charge the 24V lithium battery, a 33～36V solar battery is required. The following mainly introduces the relationship between the power of the light source, the voltage capacity of the lithium battery, and the volt power of the solar street light panel.

W (energy) = P (power) × T (time)
According to the law of conservation of energy, the solar panel converts light energy into electrical energy through photoelectric conversion and is stored in a lithium battery. The electrical energy in the lithium battery is converted into light energy to provide energy to the LED at night. The three have a common unit called watts. When Wh, 1Wh=1W × 1h, for example, the energy consumed by a 1W light for one hour is 1Wh. There is another word in physics that means energy, called Joule J, 1J = 1W × 1S (seconds), for example, A 1W heating wire generates 1J in 1 second, so 1Wh = 1J × 3600s = 3600J. Both actually represent energy. The difference is that Joule is generally used to represent heat energy, such as the very classic Joule's law in physics. (Joule's law is the law that quantitatively states that conduction current converts electrical energy into heat. The content is: the heat generated by the current passing through the conductor is proportional to the square of the current, proportional to the resistance of the conductor, and proportional to the time it takes to energize.

Why LED lights generate heat is actually because part of the electrical energy is converted into heat energy. The greater the current, the greater the heat generation, and the greater the resistance, the greater the heat generation. Therefore, the high-power LED lights of the mains must be designed for heat dissipation. Solar energy Why do we say that the thickness of the copper wire is important? It is also closely related to this Joule's law. )

W=U (Lithium battery voltage) × C (Lithium battery capacity)
C (Lithium battery capacity) = I (current) × h (time)
W=U (lithium battery voltage) × I (current) × h (time) = P (power) ÷ h (time)
The maximum charging current of the solar panel is I (current) = P (solar panel power) ÷ U (solar panel voltage)
We take the average sunshine time as the working time of the solar panel, and the capacity that the solar panel can charge the battery in a day is: C (capacity) = I (current) × h (average sunshine time) = P (solar panel power) ÷ U (Solar panel voltage) × h (average sunshine time)
The energy-charged into the lithium battery is: W = U (lithium battery voltage) × C (capacity)
Theoretically, the energy used by the lamp holder in a day cannot exceed the energy of the solar panel to charge the lithium battery in a day, otherwise the solar lamp will not be able to light up all night. recommended for you

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