How to Decide the Right Battery Size for Solar Street Lights

When deciding the right battery size for solar street lights, there are certain things which one needs to consider before reaching the appropriate decision. It can be difficult to select the accurate size of the batter, but this guide will make it much easier for you.

Normally, if the batter is undersized, the street light would not be able to work in case of three or more rainy days. Whereas, if the battery is oversized, then you would have to face sulfating, so follow this guide to choose the battery size as per your needs.

Deep Cycle Batteries

The battery type that is used for an off-grid solar streetlight is a deep cycle battery. The thing is that not every type of battery would be suitable for off-grid solar street lights and the deep cycle batteries have been designed for it. The off-grid solar street light requires permanent power supply from batteries and not from an electric company; hence, the battery should be strong enough to provide deep discharges.

Essential Terms That You Must Know About

Battery Capacity and Power

The amount of energy which is supplied by a battery at a time is the power rating and it is measured in Watts. The battery capacity is the aggregate amount of energy which can be stored in a battery.


It is another word for battery capacity. For example, if the nominal voltage of a battery is 12V, then, it would continue to release about 2 Amps currents for a period of 10 hours.

Depth of Discharge

It refers to the amount of energy which is available and can be used in a battery when it has reached a completely charged state to a completely discharged one. It is a very important factor in deciding the right batter size for solar street lights.

Battery Working Temperature

This is the ideal environmental temperature for the battery. Normally, it is 27 degrees centigrade or 80 Fahrenheit since the internal reaction of the battery is optimal at the temperature. As the temperature lowers, the efficiency would decrease. As a rule of thumb, higher temperatures improve the efficiency. However, only if the temperature is a little over the optimal temperature and it would only be so for a short time.

Step by Step Guide

For the first step, you need to prepare the required data such as the rated working voltage of the LED, rated LED power, the days of autonomy, LED brightness settings, and battery type.

Next, you need to calculate the daily energy consumption and keep the 3 days autonomy in mind. Finally, consider the depth of discharge. It is quite simple to calculate the right size for solar street lights once you understand the steps and the meaning of essential terms.

Always remember to keep the temperature in mind as you do not want the battery to be sulfating as it would only lead to increased costs over the long run.

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *