Lithium-ion solar batteries are a popular choice for home energy storage due to their long lifespan, low maintenance requirements, and compact size compared to other battery types.
When used with solar panels, these batteries store excess solar energy for later use, such as during the night or during power outages. In some regions, lithium-ion batteries can even help reduce electricity bills.
Here’s a closer look at what you should know before installing a lithium-ion battery system.
Lithium-ion batteries are rechargeable energy storage solutions that can be used independently or in conjunction with a solar energy system to store excess power.
When used alone, lithium-ion batteries can be charged directly from the grid, providing backup power during outages and helping to manage peak electricity rates. By charging the battery when electricity is inexpensive and discharging it during peak rate times, homeowners can reduce their energy costs.
When paired with solar panels, lithium-ion batteries offer the greatest value, especially if net metering is not available. The battery stores excess solar energy generated by your panels, allowing you to power your home entirely with solar energy even when the sun isn’t shining.
Lithium-ion batteries are a popular choice for homeowners seeking efficient battery storage for several compelling reasons:
The Depth of Discharge (DoD) measures the proportion of stored energy that has been used relative to the battery's total capacity. Lithium-ion solar batteries are deep-cycle batteries with DoDs around 95%, allowing you to use a significant portion of the stored energy. In contrast, typical lithium-ion batteries have DoDs closer to 50%, meaning you can use more of the battery’s energy and need to charge it less frequently.
Due to their high DoD and infrequent charging cycles, lithium-ion batteries have a longer lifespan. Most lithium-ion solar batteries come with a minimum warranty of around 10 years or approximately 10,000 cycles, whichever comes first. In comparison, lead-acid batteries typically have a shorter warranted lifespan of about 5 years.
Energy density refers to the amount of power a battery can store relative to its physical size. Lithium-ion batteries offer higher energy density than lead-acid batteries, allowing them to store more power in a smaller space, which is ideal for homes with limited space.
Lithium-ion batteries boast a higher round-trip efficiency compared to other types of solar batteries. Efficiency measures how much usable energy you get from the battery compared to the energy required to store it. Lithium-ion batteries generally have efficiencies between 90% and 95%.
One of the significant advantages of lithium-ion batteries is their minimal maintenance requirements. They need little to no regular upkeep beyond ensuring they are free of debris. In contrast, lead-acid batteries often require frequent maintenance, such as managing off-gassing.
Despite their many advantages, lithium-ion batteries do have some drawbacks:
Lithium-ion batteries are typically more expensive than other battery storage options, particularly when compared to lead-acid batteries. However, solar battery systems can qualify for incentives such as the federal tax credit, which helps offset the cost. It's also worth noting that while lead-acid batteries may have a lower initial price, they generally need to be replaced more frequently, potentially increasing your overall storage costs.
Lithium-ion batteries are at a higher risk of thermal runaway, which is a condition where the battery overheats and potentially catches fire. Although this risk exists, the likelihood of such an event is very low when the battery is properly installed and maintained.
There are two main types of lithium-ion batteries used for home energy storage: Nickel Manganese Cobalt (NMC) and Lithium Iron Phosphate (LFP).
Nickel Manganese Cobalt (NMC) batteries use a cathode made from a blend of nickel, manganese, and cobalt. These batteries are often what people refer to when discussing lithium-ion technology. NMC batteries gained popularity for their superior performance compared to lead-acid batteries, making them a mainstream choice for energy storage.
Lithium Iron Phosphate (LFP) batteries feature a cathode composed of lithium iron phosphate (LiFePO4). The materials used in LFP batteries, particularly iron and phosphate, are more abundant and less costly than the cobalt used in NMC batteries. This makes LFP batteries more affordable and easier to recycle. Additionally, LFP batteries are known for their enhanced safety due to their resistance to thermal runaway and better tolerance of temperature fluctuations. They also lack toxic materials, making them a safer and more environmentally friendly option compared to NMC batteries.
Lithium-ion solar batteries are an excellent choice for residential solar energy systems due to their compact size, substantial energy storage capacity, long lifespan, and low maintenance requirements. They offer more usable energy and longer durability compared to lead-acid batteries.
However, in some cases, lead-acid batteries may be more suitable. If you need a solar battery primarily for backup storage rather than daily use, or if you’re working on an off-grid solar project, lead-acid batteries can be a cost-effective solution that meets your needs without significant expense.
