How to Choose the Battery of Solar Powered Street Lamp?


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Rechargeable battery is the core component of solar powered street lamps. It stores and releases electrical energy, and its function is equivalent to an electrical energy warehouse. The energy of solar powered street lamp is unstable, the energy is strong during the day but no energy is provided at night. The solar powered street lamp needs to work at night, so the solar powered street lamp system needs to be equipped with rechargeable batteries.

The working principle of the battery is to store the electric energy produced by the solar modules during the day as much as possible to meet the needs of electricity consumption at night. In addition, it is also necessary to consider being able to meet the needs of lighting in rainy and cloudy days. Therefore, the capacity of the battery should match the solar components, light source and lighting time. If the battery power is too small,  it can’t provide enough lighting; If the battery power is too large and the battery will be difficult to be fully charged, which affects the lifespan of the battery and also increases the cost.

solar powered street lamp

So how to choose solar street lamp battery? Let's first look at the classification of batteries:

1. Lead-acid/gel battery: This type of battery has a cycle life of 300-500 times. It is characterized by low price, complicated installation, large size, serious pollution, and short life.

Lead-acid/gel battery

2. Ternary lithium battery: The cycle life is 300-500 times. It is characterized by low price, simple installation, small size, no pollution, short life, low safety performance, and poor high temperature performance.

Ternary lithium battery

3. Lithium iron phosphate battery: The cycle life is 2000 times. It is characterized by high price, simple installation, small size, no pollution, long life, high safety, and good high temperature performance.

Lithium iron phosphate battery

We can see from the above comparison that the cost performance of lithium batteries is relatively high. As a professional solar street lamp manufacturer, EXC always insists on quality first, and uses high-quality lithium iron phosphate batteries to make solar powered street lamps cost-effective.

In addition to understanding the classification of the battery, the capacity of the battery is determined by the following factors. To choose the correct battery, the following factors need to be considered:

1. The number of working days of the battery alone. Under special climatic conditions, the battery can discharge up to the remaining capacity of the battery accounting for 20% of the normal rated capacity.

2. The battery discharge capacity per day. For occasions where the daily load is stable and not demanding, the depth of the daily discharge cycle can be limited to 80% of the rated capacity of the battery's remaining capacity.

3. The battery must have sufficient capacity to ensure that it will not lose water due to overcharging. Generally, when selecting the battery capacity, as long as the battery capacity is greater than 25 times the peak current of the solar power panel, the battery will not cause water loss during charging.

4. The electric energy leaked by the battery itself will increase its self-discharge rate as the battery life increases and the battery temperature increases. For new batteries, the self-discharge rate is usually less than 5% of the capacity. But for old batteries of poor quality, the self-discharge rate can be increased to 10% to 15% per month.

5. The length of continuous rainy days determines the capacity of the battery. When purchasing solar powered street lamps, you need to provide the longest number of continuous rainy days that may occur in the local area so that engineers can recommend batteries of suitable capacity.

If you want to know more about the design of solar street lamp, please feel free to contact us, we will provide you thoughtful suggestion.