Solar Battery Storage in 2018: Lead Acid or Lithium Ion?

by Anna Gretz
December 15, 2017
Home Battery

If you’re kicking off 2018 with lead acid battery, it’s time to do some more research on the best way to store solar energy.

Whether you’re looking to store additional energy for back-up power, or want to get off-grid entirely, using lead acid batteries is no longer the cleanest, quietest, or most dependable option. Most people with energy storage also have a way to generate energy on-site. A common source of at-home energy generation is rooftop solar panels. Rooftop solar is a fantastic way to harness the free, clean energy that the sun gives off every day--there’s a good reason why solar panel sales are growing exponentially every year. When the sun goes down, however, rooftop solar owners are stuck drawing electricity from the unstable and unreliable power grid. Solar energy storage is the best way to keep a stockpile of solar energy for use when you need it the most, like after the sun goes down, or in the case of a power grid outage.

Decades ago, lead acid batteries were at the forefront of the residential energy storage scene… but lately, they’ve lost their luster in comparison to lithium-ion battery technology. Want the details? Keep reading.

Lithium-Ion Batteries: The Greatest Electrochemical Potential

It took a while for lithium ion batteries to gain popularity since their introduction in the 1970s, but once people caught on to how little lithium-ion batteries weighed in comparison to their multiple-hundred-pound lead acid competition, they were sold. Lithium is the lightest of metals, and has the greatest electrochemical potential. Basically, this means that per pound, lithium ion batteries are going to give you the most energy density. Since they are far lighter and more efficient than lead acid batteries, they really up the convenience and usability factor for residential solar customers.

Making Clean Energy Even Cleaner

If you’ve ever looked into the environmental impact of lead acid batteries, you were likely unimpressed. Lead acid batteries require a lot more req materials to produce than lithium-ion batteries do, meaning more mining, and a bigger environmental impact. The lead acid battery industry itself also requires a lot of energy to sustain--large quantities of pollution are released into the air and surrounding areas during the production of lead acid batteries.

Lithium-ion batteries, in comparison, require much less mining because they need less raw materials. Many solar battery manufacturers are also looking for ways that they can use renewable energy sources for power within their factory itself, like Tesla’s Gigafactory. Going the renewable energy route can result in an impressively small carbon footprint, coming from a factory that enables others to decrease their own carbon emissions as well. That’s what we like to see.

Lithium-Ion Outlasts Lead

Lithium-ion solar batteries have a significantly higher cycle life than lead acid batteries do in deep discharge applications. This means that lithium-ion batteries can support a higher number of complete charge/discharge cycles before their capacity falls under 80%. Recent data shows that a lead acid battery would have to be 2.5 times larger in capacity than a lithium-ion battery to get comparable cycle life. When you’re considering bringing a solar battery into your home, size matters.

The difference in cycle life is even greater in extreme climates. In warm climates where the temperature hovers around 90 degrees Fahrenheit, the difference in cycle life between lithium-ion solar batteries and lead acid batteries is huge. In these extreme temperatures, it takes less than 1000 charge/discharge cycles for lead acid batteries to drop below 80% in retention, while lithium-ion batteries wouldn’t see that much of a drop until at least 2000 cycles. This huge jump in battery lifetime is an exciting development for consumers who don’t want to worry about their solar home battery capacity dropping when they need power the most (like when your air conditioner is pretty much keeping you alive.)

This also means that lithium-ion solar home batteries won’t require replacement nearly as quickly as lead acid home batteries. After charging and discharging a lithium-ion solar battery thousands of times, it remains highly functional. Lead acid batteries decline much more quickly, leaving solar home battery owners with thoughts of replacement looming in the near future. More frequent replacement means less return on the initial investment made in each solar home battery system.

Lithium-Ion Batteries Provide Worry-Free Energy Storage

Another inconvenience of lead acid batteries comes in the amount of maintenance each unit requires to prolong its battery life. Lead acid solar home battery users need to keep track of battery voltage, water levels, overcharge functions, and routine electrolyte maintenance. All this information is necessary to make sure lead acid solar home batteries are being maintained and serviced on a regular basis. Failure to track this data could result in even more costly repairs, or even earlier replacement of the solar home battery itself.

Lithium-ion solar batteries, on the other hand, are virtually maintenance-free, allowing owners to enjoy using their solar home battery without worrying about permanent damage due deep discharge. There are many other things in life that demand and captivate our attention. Your solar home battery no longer has to be one of them. Your solar home battery system can now be here to support you and your household, instead of the other way around.

Li-Ion Batteries Boast Better Recyclability

Currently, lead acid solar batteries are recycled much more frequently than lithium-ion batteries, boosting their case for environmental friendliness. Lithium-ion solar batteries, however, have a very high ability for recovery and recyclability, even though their recycling rate is lower than lead acid batteries. The reason for the lower recycling rate of lithium-ion home batteries is simply because the technology is still emerging, and the machinery needed to recycle them is still costly, and in a more developmental stage. As the industry grows, lithium-ion solar battery recycling is expected to quickly rival lead acid batteries, and perhaps even surpass it due to the lower cost of using recycled lithium instead of mining more. Watch for some major advancements in lithium-ion solar battery recycling in the years to come.

Lighter Batteries, Lower Cost

The cost of transporting and installing lead acid batteries has been historically discouraging to consumers. The sheer weight of lead acid solar home batteries makes them difficult to transport, and harder to install. Because of the weight of lead acid solar battery materials, there is no easy way to cut this cost. Instead, many are turning to lithium-ion solar batteries to offer a lighter alternative.

Lithium-ion solar home batteries weigh much less, lowering shipping costs by 80%. The installation cost of lithium-ion solar batteries are similarly cut by over $16 per kilowatt hour. This makes the price of lithium-ion solar home batteries considerably lower to ship and to install, making them much more appealing to consumers. With the rising demand for solar home batteries across the country (and world), lower transportation and installation costs will become more and more important.

Lithium-Ion Batteries Complete a Smart Home

New solar home battery models have revolutionized residential energy storage by being connected and controlled by the cloud. “Smart” technology is infiltrating all devices (think phones and televisions) and solar home batteries are no exception.

Smart home batteries will give renewable energy users, like those with solar panels, huge advantages. Smart solar home batteries have the ability to learn weather and energy trends, so they can focus on storing energy during the sun’s hours of peak performance to make sure it’s available when the sun’s rays are not as strong. This practice can help maximize power usage, and also minimize the waste of energy when its abundant. Smart solar home batteries also facilitate communication with solar home battery owners, and are able to accept wireless commands, giving owners even more control over their energy.