Solar Street Light Battery: What to Know And How to Choose

Solar Street Light Battery What to Know And How to Choose

In the field of renewable energy, solar power generation, one of the most common and advanced technologies, is becoming more widely used and developed. A solar street light battery is a device that can convert solar energy into electricity and store it, and it is also a key component of a solar power generation system. In this passage, we will share all of the important knowledge about the solar street light battery. Let’s get started!

Is there a difference between solar light batteries and regular batteries?

Electrochemical performance differences: solar batteries have lower internal resistance and higher charging efficiency and can be charged in the case of insufficient light. General battery charging efficiency is relatively low and more prone to overcharging and overdischarging.

Deep discharge capacity difference: solar batteries have a strong deep discharge capacity; even at low power, they can maintain a longer time of discharge. However, in a state of deep discharge, the common battery is prone to capacity attenuation and life shortening.

Is it necessary to install batteries in solar street lights?

composite of solar street lights

The batteries are necessary for the solar street lights, and the reasons are as follows:

  1. Solar panels convert light energy into electricity, but they cannot store electricity.
  2. When there is sufficient light, the solar panels can generate a high electromotive force. But they can only produce a low electromotive force when the light is weak. So they cannot supply power to the devices with this unstable output voltage.

Therefore, a complete solar power system also needs the conversion modules and the batteries. The conversion modules will work to transform the unstable voltage into a stable one, and the batteries can then store the energy. The energy they store during the day can be used at night and can also power the lights on rainy days.

4 types of the solar street light battery

Lead-acid batteries

Lead-acid batteries consist of multiple positive and negative electrodes and electrolytes. The positive electrode consists of lead steel mesh, lead oxide, and stabilizer; the negative electrode consists of lead steel mesh, lead, and stabilizer; and the electrolyte consists of sulfuric acid and deionized water.

Lead-acid batteries are relatively cheap to produce, making them popular among different types of batteries. Secondly, the design of the lead-acid battery is simple and easy to maintain, has a relatively stable voltage output, and has a long life; it can generally be used for 2-5 years. Correspondingly, lead-acid batteries also have some disadvantages. The main disadvantage is that the weight is large, the volume is not small, and the need for frequent charging is easy to appear as a memory effect, resulting in a sharp decline in energy storage capacity. Secondly, lead-acid batteries may cause environmental pollution.

Colloid Battery

The colloidal battery belongs to a lead-acid battery, but it improves the performance of the old lead-acid battery to a large extent. It replaces the sulfuric acid electrolyte with a colloidal electrolyte. In this way, the colloidal battery obtains more power storage and a longer service life. It has better discharge performance and is safer. There is no free liquid inside the gel-like electrolyte, avoiding the thermal runaway phenomenon of the general battery. Besides, it has a slight corrosion effect on the plate, and the electrolyte will not delaminate. However, its production technology is difficult, and the cost is high.

Lithium iron phosphate battery

There is an olivine structure (LiMPO4) in the lithium iron phosphate battery. This material is easier to find, cheaper, and more environmentally friendly than traditional lithium ion secondary battery cathode materials. A lithium iron phosphate battery can charge and discharge with a high current quickly and safely. In addition, it is also resistant to high temperatures; lithium iron phosphate’s electric peak can reach 350 °C to 500 °C, while lithium manganate and lithium cobaltate are only about 200 °C. Its disadvantages include poor electrical conductivity and low temperature resistance.

Lithium Ion battery

Ternary lithium battery

Ternary lithium batteries are a kind of lithium battery. Some anodes use nickel, cobalt, and manganese, while others use nickel, cobalt, and aluminum. The Ternary lithium battery is safe and will not pollute the environment. It has a high output voltage and a large capacity, and at the same time, the output voltage is very stable. However, the structure of nickel, cobalt, and aluminum is unstable at high temperatures, which is a potential danger, so the costs of production are high.

Specifications of solar street light battery

Different voltages

The nominal cell voltage of different types of batteries is different. The nominal cell voltage of a lead acid battery, a gel battery, a lithium iron phosphate battery, and a ternary lithium battery is respectively 2.2 V, 2.35-2.4 V, 3.2 V, and 3.7 V.And usually, when we are choosing the battery, the voltage we find is the voltage of the battery pack. The value is normally 12 V, 24 V, and so on. They consist of several batteries of a certain type. Batteries with a higher voltage are more expensive, but their endurance capability is better. Besides, you should also decide which type of batteries you want.

How to calculate battery capacity for solar street lights?

You need to consider how many days you need your lights to light up for and how many hours they should work for a day. In addition, since the battery cannot overcharge or overdischarge, you need to increase the estimated value of the capacity. Also, think about the loss of the circuit.

The unit of capacity is Ah, so you need to figure out the value of the current and the working time. As for current, it is determined by voltage and power. Suppose your battery has a voltage of 24 V and there are two 50 W LED lights in the system; then the current will be 100 W/24 V = 5 A.

If you want your light to work from 7:30 p.m. to 5:00 a.m., maybe the working time is not 9.5 hours but less. Because usually we will only need half the power at midnight to save energy, Of course, it depends on your configuration. We will count it as 7 hours for our example. And then you should think about how many days you need it to work for—for instance, five rainy days.

Battery capacity =5 A x 7 h x 5 days =5 A x 35 h =175 AH

But 175 Ah is not the final answer. Since the battery cannot overcharge or overdischarge, you will need a larger capacity. So maybe 175 Ah is only 70%-85% of the needed capacity. In addition, the actual current should also increase by 15%-25% because there will be a loss in the current.

What is the battery life of solar street lights?

The lifespan of the battery is affected by multiple factors, such as the temperature, time of discharge, and depth of discharge. Generally, lead-acid batteries have a lifespan of 3-5 years. As for lithium-ion batteries, they have many advantages, like higher energy density and a lower self-discharge rate, so their lifespan is also longer. These batteries can last for about 5-15 years.

When should I replace my solar light battery?

  1. When the battery charges fast: Normally, it takes hours for the batteries to be fully charged. So it may be a sign if the batteries are fully charged within several minutes.
  2. If the voltage is lower than the rated voltage while connecting but suddenly rises when the battery is disconnected, then there may be something wrong with the battery.
  3. When the power supply time shortened: Your battery performance typically deteriorates over time. So you’d better replace the battery before it expires.

Where to install the solar street light battery?

Buried box: It is generally under the specially built cement next to the light pole, but this place cannot achieve a good insulation, gas, or waterproof effect.

Battery box: There are also some batteries at the bottom of the light pole in a specially welded battery box. Disassembly is very convenient, but under high temperature conditions, it has an impact on the life of the battery.

On the lamp: The lithium battery has a small volume and large capacity and can be placed under the solar panel, packaged with an insulated battery box and fixed under the panel, or placed in the lamp holder.


In the above passage, we talk about the introduction, types, and specifications of the solar light battery. For more useful information, you can visit and check out our blogs. Mokolight is an expert in the field of LED street lights. You can find high-quality LED lights for solar street lights at Mokolight, and these lights are guaranteed by certifications like CE and RoHS. As a professional manufacturer with over 17 years of experience, Mokolight will never let you down!

Written by ——
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
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