Tedlighting experts recommend using the LiFePO4 battery because it is non-combustible and highly thermally stable. Still, if you are thinking what to choose, LiFePO4 Battery vs Lithium Battery: Which Is Better for Solar Street Lights? We are going to help you figure out in this blog.
What is The System Used in Solar Street Lights?
The solar street lights are operated with an independent grid system. Solar Street Lights have a photovoltaic (PV) system with 5 components:
- Solar Panel (PV Module)
- Solar Charge Controller
- Battery Bank
- LED Light Fixture
- Pole and Housing
These components work to make the street lights efficient. Now, the next question you might be wondering is how to choose the battery for a solar street light. We are here with detailed answers in the next section.
The Battery Calculator for the Solar Light:
When you are going to buy the LED solar light, you must also know that a perfect battery will help you run the light perfectly. A good battery has reliable nighttime performance, with longer life span, and it is operational in cloudy and rainy weather as well. There are three factors on which your battery size depends, including the following:
- LED light power consumption
- Daily operating hours
- Number of backup (autonomy) days required
This guide explains the battery sizing process using industry-standard solar street lighting calculations.
Step 1: You Should First Calculate Daily Energy Consumption
The simple thing you can do is to make sure how much energy is consumed by the LED street light every day; for this, we have a formula that you can use. Formula:
Daily Energy Consumption (Wh)=Lamp Power (W)×Operating Hours (h)
An Example for you to understand it better:
A 40W LED solar street light operating for 12 hours per night: 40W×12h=480Wh
Daily energy requirement will be 480Wh.
The daily energy consumption forms the foundation of the entire solar street light battery sizing calculation. If you need longer operating hours or the wattage is high for LED lights, then you must make sure to buy the battery with longer life span.
Step 2: Calculate Energy Required for Backup Days (Autonomy)
Solar street lights must continue operating during periods of limited sunlight. This is known as battery autonomy.
Most commercial solar street lighting systems are designed for:
- 3 days autonomy (standard)
- 4–5 days autonomy (areas with frequent cloudy weather)
Formula:
Required Energy (Wh)=Daily Consumption (Wh)×Autonomy Days
An Example for you to understand it better:
For 3 days of backup:
480Wh×3=1440Wh
Total required stored energy = 1,440Wh
Autonomy ensures your solar street light remains operational during:
- Rainy days
- Winter weather
- Extended cloud cover
- Reduced solar charging conditions
Step 3: You Must Check the Battery Depth of Discharge (DoD)
The most important thing to know is that your battery should not completely discharge. There is a recommendation for the Depth of Discharge (DoD). This affects the performance and lifespan of the battery.
Typical DoD Values:
| Battery Type | Recommended DoD |
| LiFePO4 Battery | 80% (0.80) |
| Lithium-Ion Battery | 60% (0.60) |
| Lead-Acid Battery | 50% (0.50) |
Formula
Adjusted Battery Capacity (Wh) = Required Energy (Wh)/Dod
Example Using LiFePO4:
1440Wh/0.80 = 1800Wh
Adjusted battery storage requirement = 1,800Wh
Modern solar street lights commonly use LiFePO4 batteries because they offer:
- Longer lifespan
- Higher efficiency
- Better temperature performance
- Greater depth of discharge
- Lower maintenance requirements
Step 4: Convert Watt-Hours (Wh) to Amp-Hours (Ah)
Battery manufacturers typically rate batteries in Amp-hours (Ah). If you want to determine the capacity of the battery, you can follow the simple formula.
Formula
Battery Capacity (Ah) = Adjusted Energy Capacity (Wh) / Battery Voltage (V)
Example Using a 12.8V LiFePO4 Battery:
1800Wh/12.8V=140.63Ah
Required battery capacity = approximately 141Ah
Since batteries are sold in standard sizes, always round up to the next available capacity.
Conclusion
LiFePO4 Battery vs Lithium Battery: Which Is Better for Solar Street Lights? Our recommendation will always be the LiFePO4 Battery because they have longer lifespan. With our experience of decades working with solar lighting, we have always suggested these batteries, and over 500+ customers are using it with no complaints, including residential and commercial projects.
