November 05, 2020

Solar Battery Chemistry Explained: Know your Elements

Solar Battery

Battery storage has revolutionized the renewable energy landscape – helping to solve two of solar power’s greatest limitations:

  1. Some days are cloudier than others
  2. At night, there is no sunshine at all


With batteries, you can capture and store daytime solar power for overcast days or when the sun finally sets. As an added benefit, you can manage energy usage to avoid demand charges or load shift when time-of-use (TOU) pricing goes up. As a result, you benefit from:

  • Increased monthly savings
  • Greater energy independence
  • Shorter payback periods
  • Higher carbon savings
  • Better returns on your investment

However, not all solar batteries are created equal. And before committing to one technology or another, it is important you understand the pros and cons of the two leading storage options – lithium-ion (LI) batteries and lithium-iron phosphate (LFP) batteries.


How Do Solar Batteries Work – and Which Type Should You Choose?

Batteries store chemical energy that can be converted into electrical energy whenever “work” is required. This is true for AAA batteries on up – with the spectrum of chemicals ranging from lead acid to salt compounds to everything in between. But for modern applications like solar storage and electric vehicle (EV) charging, the two most common battery technologies are lithium-ion and lithium iron phosphate.


Which solar battery is right for your solar installation?


Lithium-Ion Solar Battery: Pros and Cons

Also known as a lithium cobalt battery, the lithium-ion solar battery is basically an upgraded version of the storage technology used in most mobile devices and laptop computers. It is versatile and affordable, making it a common favorite for many solar applications. Tesla’s fleet of electric vehicles also relies heavily on this storage technology.

However, the lithium-ion solar battery has several drawbacks:

1. Thermal Runaway

Lithium-ion batteries are prone to overheating. You have likely seen this with your own smart device or laptop. But lithium-ion battery safety is an even bigger problem with larger applications like solar storage. Worse still, minute increases in temperature often lead to further increases in a phenomenon known as thermal runaway. And if left unchecked, this can result in fire, injury, or even death.

2. Limited Lifecycles

Because of their higher operating temperatures, lithium-ion batteries are not as resilient as other storage technologies. They carry a limited number of charge cycles, with the average lifespan of a typical lithium-ion battery lasting two to three years for most consumer electronics. In solar applications with larger batteries, the warranty coverage is closer to five years (or 2,000 cycles). This means you may have to replace your batteries at least five times over the 25-year warrantied lifetimes of your solar panels.

3. Health and Environmental Risks

Lithium-ion batteries rely on cobalt to help with electrical conductivity during the charging phase. Adding this element increases the overall stability of the battery. But cobalt is a rare material that is difficult to mine ethically. Moreover, it is toxic to humans and animals – making its continued use both a public and environmental health risk.


Lithium Iron Phosphate Solar Battery: Pros and Cons

Lithium iron phosphate batteries are technically a derivative of more traditional lithium-iron batteries – with both sharing many of the same advantages. But this newer storage technology offers several important benefits absent from their lithium-ion counterparts:

  • LFP solar batteries rely on phosphate instead of cobalt – eliminating many of the health and environmental risks that lithium-ion solar batteries pose.
  • The lack of cobalt also makes lithium LFP solar batteries cheaper to manufacture. Phosphate is both easier and less expensive to mine responsibly.
  • Due to their phosphate composition, LFP solar batteries run cooler – with less wear and tear. Equally important, they do not pose any of the fire-safety risks (i.e. thermal runaway) commonly associated with the lithium-ion solar battery.

Because of these benefits, LFPs deliver unrivaled durability and performance compared to most other storage technologies. And if you are worried about lithium-ion battery storage safety, LFPs pose fewer environmental, health, and fire risks.

A Better Approach to Solar Battery Safety and Performance

Having on-site storage is better than having none at all. But if your goal is to maximize the ROI of your clean energy investment, LFP solar batteries are the clear winner given their cost, performance, durability, and environmental sustainability.

These benefits explain why we have designed our own Enphase storage system around lithium iron phosphate technology. And by subjecting our batteries to strict quality controls and rigorous stress testing, we are able to ship our high-performance solar storage solutions with an industry-leading warranty of 10 years (or 4,000 cycles). This extended coverage helps to ensure you continue enjoying the above benefits for as long as possible.

To learn more about lithium-ion battery safety and why we recommend LFP storage technology instead, schedule a free consultation with one of our clean energy experts today.

Questions? Contact us. We'll help you build your system, today.
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