The Solar Light Battery Challenge

A solar lighting system is a bit of a tricky thing, which is why it’s necessary to have a lighting engineer size your system properly. The reason why solar needs proper engineering is because one wrong aspect of power can cause the system to malfunction. That’s why batteries tend to be a challenge for a system; you’ll need something that can sustain the levels of light and then store enough energy for the next day-night cycle. The battery used must be able to supply the light with enough power to last a long time while also charging enough to replenish the power used.

Battery Types

Not all solar light batteries are created equal. It’s important to understand the technology behind the battery or batteries you’ll use in your solar lighting system, because otherwise, you may be sinking money into a component that fails early. The right type of battery is required to ensure your solar lights will stay on even in the darkest stretches of the year.

There are several battery types on the market, but the main types that are the most commonly used in solar lighting are gel lead-acid, AGM lead acid, lithium-ion, and nickel-metal hydride.

Lithium-Ion batteries are very popular because they’re used in small electronics--laptops, cell phones, tablets, other devices. However, using this kind of battery in a solar light isn’t a great idea because--especially when they’re higher capacity--they’re liable to catch fire and explode. Remember, batteries will be sitting in the sun for extended periods of time and so precautions about what kind of battery your system will need are important.

Nickel-Metal Hydride batteries are more popular in smaller solar projects and definitely more viable than Li-Ion. However, they are notorious for self-discharging over time and aren’t the best idea for long-term, repetitious use. 

Lead-acid batteries are the most popular batteries for solar street lighting systems. We’ll dive into a few reasons why here in this next section.

The Best Solar Light Batteries are Deep-Cycle Lead-Acid Batteries

Batteries are complex devices because they take in electrical power, store it as a chemical, and then revert it back to electrical power when needed. Lead-Acid batteries have certain qualities about them that make them ideal for solar street lights:

Constant Charge-Discharge

Solar lights work on a daily cycle of gathering energy and utilizing energy--thus, you need a battery that can charge and discharge constantly. These kinds of batteries can take this constant rate of charge-discharge easily without losing too many power cycles. 

Great Depth of Discharge

A depth of discharge refers to how much a battery can be safely discharged without too much energy to sacrifice. If a battery drains below the recommended level, it can sacrifice overall power cycles and battery health. 

A lead-acid battery’s optimal DoD is about 15%. A properly-sized solar lighting system will most often drain the battery to this level. The max recommended level is 20% of the battery’s total power. 

If there’s a drain beyond this, the system is either sized incorrectly, the battery from the manufacturer is not a quality lead-acid battery, or there are other problems to address with the solar lighting system. Ensure your batteries are quality, or else you may see irreparable damage to your system.

All-Weather Resilience

The batteries are self-heating, so if they’re out in the cold they’ll be able to withstand the temperature drop. They survive well in the heat. However, if the environment isn’t the best for them to keep their optimal charge, you can opt to bury them

Conclusion

There are many solar light batteries on the market, and it’s important you know which ones operate the best for your lighting system. Purchasing the wrong battery could lead to money lost or a safety hazard for the public. Be aware of where your money goes. If you're interested in moving forward with a project with Greenshine new energy, contact us for a quote. Feel free to browse our solar lighting guide for 2020 as well.