One of the oldest battery types, lead-acid batteries use a sulfuric acid electrolyte fluid to submerge lead plates creating a chemical reaction conducive to storing and discharging electrical currents. One of the main advantages of lead-acid batteries is that they are the most common type of battery available, making them very easy to find. Because they are common, they tend to be the most affordable option as well. Additionally, lead-acid batteries provide consistent and stable power output for the long term. They will generally be easy to replace or upgrade if you need to switch them out or upgrade them.
Some drawbacks of lead-acid batteries include their size and weight. They are often cumbersome and take up a fair amount of space. Their ambient working temperature is also lower than room temperature, so using them will necessitate you having an environment available to keep them cool.
Lead-acid batteries are a popular option for creating off-grid solar setups and emergency backup power systems.
Lithium-ion batteries are made up of various metal sheets, separated from each other by polyolefin, and submerged in a lithium salt solution. Similar to lead-acid batteries, the arrangement of these materials within a lithium-ion battery creates a chemical reaction that directs electricity in and out of the battery for storage and discharge.
Lithium-ion batteries have many advantages, starting with the fact that they require little to no maintenance. They are also more energy-dense than lead-acid batteries, which allows lithium-ion batteries to come in smaller sizes while still packing the same energy capacity. Additionally, they can work reliably in environments with more temperature fluctuations. One of the biggest benefits of a lithium-ion battery is its higher depth of discharge compared to other batteries, meaning that it can use more of its full charge in any cycle, a fact that also contributes to lithium-ions lasting longer (up to 15 years).
Downsides of lithium-ion batteries include their cost and potential fragility. The materials involved can make lithium-ion batteries more expensive than others, sometimes double what a similar capacity lead-acid battery might cost. When not used properly, a lithium-ion battery can also be fragile, so they will need a stabilizing circuit if you want to use them safely.
Most commonly, lithium-ion batteries are found in electric vehicles, but in home solar energy use cases, they are also popular as space-saving options or battery options for climates and homes with more extreme temperatures.
In a flow battery, electrolyte chemicals are housed in two separate tanks (one with zinc and the other with bromine) and simultaneously pumped past opposite sides of a graphite membrane. This interaction allows the chemicals to exchange electrons and produce a current.
Flow batteries can offer several advantages for a solar energy system. First, flow batteries are very scalable, meaning that their potential energy output scales proportionately with their physical size. Flow batteries also don’t tend to overheat during use. Finally, a flow battery has a very high depth of discharge in comparison to most other battery types, so you’ll get a longer lifespan and more power per charge from each battery.
On the other hand, there are some drawbacks to consider with flow batteries. For one, they tend to be more expensive because of the costly materials used to make them. This can also make them a challenging item to acquire since very few companies actually produce flow batteries for commercial use. Their scalability is a double-edged sword. If you have a higher energy usage, you will likely need a larger flow battery to make it work. One other thing to watch out for is corrosive and toxic materials. Zinc and bromine can be dangerous, so flow batteries should be very carefully handled to avoid exposure to these materials.
Flow batteries are best used in cases with high energy demand. If you have a large-scale system and plan on doing multiple charge cycles daily, a flow battery might be suitable for your solar setup.
4. Sodium-Nickel Chloride
Sodium-nickel chloride batteries use sodium, nickel, and sodium chloride electrodes immersed in a complex mixture of ceramic and sodium-based electrolytes. These mechanics work similarly to lead-acid or lithium-ion batteries but with different chemicals causing the reaction.
A few benefits of sodium-nickel chloride batteries include their sustainability, lack of toxic chemicals, and a broad ambient working temperature range. A sodium-nickel chloride battery is fully recyclable and does not produce any toxic chemical emissions or create any fire risks. Additionally, their ambient working temperature range spans anywhere from -4ºF and 140ºF, allowing them to function efficiently in some truly extreme temperatures.
Looking at the negatives, sodium-nickel chloride batteries usually have a shorter lifespan than other types of batteries, so long-term reliability is an issue. They also have a shallow depth of discharge, which means that a significant amount of the energy it stores is functionally unusable.
Sodium-nickel chloride solar batteries are most often used in off-grid solar installations requiring a large power load. They can also be used as emergency backup power sources.