Li-ion and LiFePO4 batteries are the best options for modern solar street lights, offering superior performance and reliability compared to traditional lead-acid batteries.
AGM and Gel batteries are the most commonly used Lead-Acid batteries for solar street lights. Lithium-Ion (Li-Ion) batteries are among the most popular batteries for solar street lights, but also the most expensive ones. They use a lithium metal oxide cathode and a lithium-carbon anode, immersed in a lithium salt electrolyte.
Lithium batteries are a more advanced technology delivering around 4,000 cycles while operating at an 80%-100% DoD. Each battery has a different type of safety certification, regarding electrolyte chemicals and the manufacturing process. Solar street lights require a battery with UL-8750 certification or a safer one.
How much battery does a 12V solar street light need?
To power a 12V solar street light for 12 uninterrupted hours (19:00 to 07:00) considering losses due to an 80% round-trip efficiency, a DOD of 50%, and taking 2 days of autonomy, you would require a 75Ah@12V battery for the 1,500-lumen fixture and nearly 600Ah@12V battery bank for the 12,000-lumen street light.
Lithium solar batteries are a rechargeable energy storage solution that can be paired with a solar power system to store excess solar power. India's installed solar energy capacity stood at around 61.97 GW as of 30th November 2022, and the government planned many projects to reach its ambitious target of increasing its share to 100 GW by 2022.
Are solar street lights safe?
Solar street lights require a battery with UL-8750 certification or a safer one. One major aspect to consider in safety measures is avoiding batteries falling under thermal runaway, this can rapidly heat the battery and cause it to explode or release hazardous gases.
To size the capacity required for the battery, it is valuable to use the expression below: As an example, we can take a 1,500-lumen fixture that consumes nearly 15W, while a 12,000-lumen solar street light consumes 120W.