The role of a battery in a solar light system is to store the electric energy converted by the solar panels. This power is later used to illuminate the light source. Solar lights use different rechargeable battery types. Below we explain in detail about different kinds of batteries used in solar lights.
- Lead–acid battery and SMF
- Lithium ion battery (Li-ion)
- Lithium iron phosphate (LiFePO4)
LEAD-ACID AND SEALED MAINTENANCE FREE (SMF) BATTERY:
Because of the price advantage, people widely use lead acid batteries. It is inexpensive compared to new technology batteries. Lead acid batteries can be used for a variety of applications and there are extensive sizes and applications available. They are tolerant to overcharging there is very low self-discharge. Lead acid batteries are considered dependable as they use a technology established over the years. However, lead acid batteries have many disadvantages compared to Li-ion and LifePO4.
They need regular maintenance and the risk of explosion is more. There are a lot of environment concerns as they contain lead and it will be difficult to handle extreme weather conditions. Two of the biggest disadvantages of using lead acid battery in your solar lights are a bigger solar panel is needed for charging and since the size of the battery is bigger, it will require a lot of space. Solar panel is to generate at least 12 V to charge the battery which means during cloudy days it will be difficult to generate 12 V. Life of lead acid battery is around 3 to 4 years.
LITHIUM ION (LI-ION) BATTERY
Li-ion battery is compact and priced higher compared to lead acid battery. These are the batteries that are used in mobile phones, laptops and cameras. It requires 3.7 V of power to charge these batteries. That means solar panel size can be smaller. During cloudy days, solar panel can continue to generate 3.7 V and these batteries can easily charge. These batteries require no maintenance and life of battery will be 5 to 6 years. Li-ion batteries efficiency reduces during very high or very low temperatures.
LITHIUM ION PHOSPHATE BATTERY (LIFEPO4)
LiFePO4 battery is compact, portable and priced higher compared to Li-ion. This technology is being widely used in most of the modern electronic devices. It is the most advanced battery type currently available in market. Since it requires only 3.2 V of power for charging, smaller-sized solar panels can be used. During cloudy days, solar panel can generate 3.2 V for the batteries to charge. There is no maintenance required and lifespan of LiFePO4 battery is around 9 - 12 years. One of the advantages of using this battery is that it can with stand extreme weather conditions and guarantee more safety and reliability.
Usage of Batteries in Solar Lights.
Unlike traditional solar street lights which use lead acid batteries, modern solar street lights use either lithium-ion or lithium iron phosphate batteries. One of the main reasons why these two batteries are chosen for solar street lights is their compact and lightweight design which makes it easy for the lights to be installed on top of a pole or a wall. Both lithium-ion as well as LiFePO4 batteries have excellent backup capacity and durability.
Solar street light that use batteries with good storage capacity can continue illuminating even on non-sunny days when there is not enough sunlight to charge the batteries. All the solar lights use in-built rechargeable batteries now and Solar garden lights, solar flood lights and solar emergency lights still continue to use lead acid, lithium-ion or LiFePO4 batteries. The installation and maintenance of solar lights are very easy with in-built battery and the price of the battery depends on the type, the capacity of the battery and the manufacturer.