The importance of battery to solar panel

Battery (also commonly known as battery) is an important component of the solar power supply system. Its main function is to store the electric energy generated by the solar panel in the battery immediately for the use of electrical equipment. The battery has the function of storing electric energy and stabilizing voltage.

The main technical parameters of the battery are voltage and capacity. Voltage refers to the rated voltage of the battery, i.e. the normal working voltage, generally including 3V, 6V, 12V, 24V, 36V, etc. Capacity refers to the capacity of storage battery to store electricity. Generally, it includes 4ah, 6ah, 12Ah, 20Ah, 40ah, 60ah, 120ah, etc. For example, taking 40ah battery as an example, it means that when the battery is charged with 4A current, it can be fully charged within 10 hours; If it is charged with 1A current, it will take 40 hours to fully charge. On the contrary, the same is true when discharging. Generally, the charging and discharging time of the battery should be 10 hours.

When charging the battery with solar cells, the voltage of the solar cells should exceed the working voltage of the battery by 20%-30% to ensure the normal charging of the battery. For example, 8-9v solar cells are required to charge 6V batteries, and 15-18v solar cells are required to charge 12V batteries.

As for how to match the solar panel when charging the battery, it mainly depends on your actual needs.

Can solar panels work without batteries?

Solar panels can not normally supply power to electrical equipment without batteries.

The reasons are:

1. Solar panels are just devices that convert light energy into electricity, but they cannot store electricity.

2. Solar panels can generate high electromotive force when the light is strong; When the light is weak, only a low electromotive force can be generated. That is, the output voltage is very unstable and cannot normally supply power to electrical equipment.

Therefore, the solar power generation system must be composed of solar panels, voltage conversion modules and batteries.

The voltage conversion module converts the unstable voltage generated by the solar panel into a voltage suitable for charging the battery to charge the battery.

The electric equipment obtains relatively stable power supply voltage from the battery.

How to connect the solar panel and the battery

When the solar cell is connected to the battery, it is best to use a photovoltaic charging controller, which can control the output voltage of the solar cell and protect the battery from overcharge. At the same time, when the solar cell does not generate electricity at night, it can prevent the battery from backflow.

The connection method is as follows:

Solar cell – photovoltaic controller – battery – DC load.

While the solar energy charges the battery, it is completely feasible for the battery to supply power to the outside. In this case, the power used by the load will give priority to the direct use of the power of the solar cell, and the rest will be charged into the battery; On the contrary, if the power of this solar cell is not enough, it will take power from the battery at the same time.

Calculation formula of solar panel and battery configuration

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 lighting time of street lamps is 9.5 hours per night, and the actual full load lighting is 7 hours (H); Example 1: 1 LED lamp

(for example, 100% power is turned on at 7:30 p.m., reduced to 50% power at 11:00 p.m., then 100% power after 4:00 a.m., and turned off at 5:00 a.m.)

Example 2: 2-way non LED lamps (low pressure sodium lamp, electrodeless lamp, energy-saving lamp, etc.)

(for example, two routes are opened at 7:30 p.m., one is closed at 11:00 p.m., two are opened at 4:00 a.m., and five are closed at 5:00 a.m.)

It is required to meet the lighting requirements for 5 consecutive rainy days. (5 days plus the lighting of the night before the rainy day, totaling 6 days) battery = 5A × 7h × (5 + 1) days = 5A × 42h =210 AH

In addition, in order to prevent overcharge and discharge of the battery, the battery is generally charged to about 90%; The remaining discharge is about 5% – 20%.

Therefore, 210ah is only about 70% – 85% of the real standard in application. In addition, the actual loss shall be measured according to different loads,

The actual working current is affected by the constant current source, ballast, line loss, etc., and may increase by about 15%-25% on the basis of 5A.

 III:Calculate the peak demand (WP) of the battery panel: the cumulative lighting time of the street lamp per night needs to be 7 hours (H);

★: the average daily effective illumination time of the battery panel is 4.5 hours (H); At least 20% of the reserve for the demand for battery panels shall be relaxed.

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, and ballast or constant current source power consumption are different, which may be about 15%-25% in practical application. Therefore, 162w is only a theoretical value, which needs to be increased according to the actual situation.

Annual average sunshine time and optimal installation inclination in major cities in China

  Calculation formula of solar panel and battery configuration

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