The Four Types of Solar Batteries

by Tyler Deken November 8th, 2022

Solar batteries are a great way to store energy captured from the sun. Without a battery, you will lose solar power every night or during cloudy days. 

You can also think of a solar battery as backup insurance that will keep your home powered during blackouts. 

Solar batteries come in all shapes and sizes, making it easy to find one that will suit your needs. Here are the four most common types of solar batteries on the market today.

Lithium-Ion Solar Batteries

  • The most popular and expensive type of solar battery, lithium-ion batteries have a high energy density and low self-discharge rate. 
  • They also have a long lifespan, often lasting up to ten years.

Lead-acid Solar Batteries

  • A cheaper option that is not as popular, lead-acid batteries have a shorter lifespan and must be replaced more often. 
  • However, they do have a high tolerance for deep discharge.

Saltwater Solar Batteries

  • A new type of battery that is very efficient and environmentally friendly, saltwater batteries use electrolytes made from water and salts. 
  • They have a longer lifespan and are less likely to catch fire than lithium-ion batteries.

Flow Batteries

  • These batteries have a separate tank filled with liquid electrolytes, allowing for easier scaling to a higher capacity. 
  • Flow batteries also have a longer lifespan and can handle deep discharge well.

Understanding Solar Battery Technology

Solar batteries allow you to store excess energy for later use. During the day, your solar panels collect power to fuel your appliances. 

If there is no immediate energy demand, this power will be stored in the battery. Without a battery, this accumulated solar energy would be wasted. 

Aside from holding backup power, solar batteries can help you avoid peak utility charges. The collected energy is stored as an alternating current (AC) to keep the power longer. 

Afterward, a solar inverter converts it to a direct current (DC), which is better at maintaining energy over long distances. Essentially AC is better for storage, and DC is better for movement.

Best for Each Scenario

  • Most homeowners will want to go with a lithium-ion battery setup for their home
  • Depending on the location, lithium-ion batteries and nickel-cadmium batteries have applications for solar light setups 

Lithium Solar Batteries


  • Most popular type of battery on the market today 
  • Long service life 
  • High energy density 

  • Cons
  • Relatively expensive compared to other options 
  • Vulnerable to high temperatures 

Average Cost: $15,000 per battery; $60,000 for a total home setup 

Lifespan: 8 to 15 years, 9 on average 

Lithium-ion solar batteries are the most popular type of solar battery on the market today. They’re also the most expensive, but they offer the best performance in terms of power and capacity. 

Lithium-ion solar batteries can last up to 10 years with proper care, making them an excellent long-term investment.

As the name suggests, the batteries work by moving lithium-ion particles between the positive and negative electrodes. 

This battery has a high energy density, meaning it can store energy in a small space. They also have a low self-discharge rate, meaning they will maintain their charge for more extended periods.

One downside to lithium-ion solar batteries is their vulnerability to high temperatures. Keeping these batteries in a cool, ventilated area is essential to ensure their longevity. 

Lithium-ion batteries can be prone to catching fire if not correctly cared for.

Most Popular Lithium-Ion Batteries

Home Grid Energy

The latest and greatest whole home battery in the world. The Home Grid Energy battery system powers your entire home at a fraction of the cost of other battery systems. It is the most most powerful battery on the market. When you bundle your Home Grid Energy Battery System you are eligible for a $7500 cash rebate from Spark Change.

Learn More

Learn More

Lead Acid Solar Battery

Average Cost: $6500 per battery; $28000 for a total home setup 

Lifespan: 3 to 12 years, 7 on average 

Lead-acid solar batteries are not as popular as lithium-ion batteries, but they offer a more affordable option for homeowners. 

These types of batteries use a lead-acid chemical reaction to store energy, and they typically have a shorter lifespan of around 3-5 years.

However, lead-acid solar batteries have a high tolerance for deep discharge, making them a good option for those who regularly drain their battery’s total capacity. 

They also have low maintenance requirements and are easy to install, but are more applicable in situations that have lower energy needs, like remote cabins, RVs, vans, and marine vehicles. 

On the other hand, lead-acid batteries have a lower energy density and can be heavy and bulky. They also have a higher self-discharge rate, meaning they lose their charge faster when not in use. 

There are two sub-variations to Lead-acid batteries.

Solar GEL Battery

Solar GEL batteries are a type of lead-acid battery. These types of batteries are commonly used for backup power. 

They have the added benefit of being sealed and maintenance-free, but they also tend to be more expensive.

Solar AGM Battery

Solar AGM (Absorbed Glass Mat) batteries are also a type of lead-acid battery, but they use an absorbent glass mat to hold the electrolyte in place. 

This makes them spill-proof and allows them to be installed in any position without leakage concerns. AGM batteries are commonly used for RV and marine applications and backup power.

Most Popular Lead-acid Batteries:

Solar Flow Battery

Average Cost: $6,000 to $26,000 for a total home setup 

Lifespan: Up to 20 years

Flow batteries, also known as redox flow batteries, store energy in liquid electrolytes held in separate tanks. 

This allows easy scaling to a higher capacity, making flow batteries a good option for commercial or industrial use.

Flow batteries also have a longer lifespan, with some estimates saying they can last up to 20 years with proper maintenance. 

They also have a high tolerance for deep discharge and can handle significant power demands.

However, flow batteries tend to be more expensive upfront and require regular maintenance to keep the electrolytes at optimal levels. 

Additionally, they can be pretty bulky due to the separate tanks needed for storage.

Most Popular Flow Batteries

Nickel-Cadmium Solar Battery

Average Cost: Varies depending on project type 

Lifespan: Up to 7 years

Nickel-cadmium solar batteries are similar to lead-acid batteries in price and performance. 

However, they tend to last longer, making them a good choice for those who need a battery that will last for several years. 

Nickel-cadmium batteries need to be replaced every 4-7 years.

These batteries have a high tolerance for deep discharge and can handle significant power demands. They also have low maintenance requirements and are easy to install.

On the downside, nickel-cadmium batteries have a lower energy density and can be heavy and bulky. They also have higher self-discharge rates and can be sensitive to temperature changes.

Most Popular Nickel-Cadmium Batteries

Factors to Compare Solar Batteries

When deciding on the best type of solar battery for your needs, consider cost, lifespan, energy density, and maintenance requirements. 

Doing thorough research and consulting with a professional before deciding is essential.

This section will empower you to understand the comparison factors of the types of solar batteries. It will help you ultimately decide the best kind of battery for you.

  • Cost: The initial cost of purchasing the battery and any recurring charges for maintenance or replacement.
  • Capacity/Power: The amount of energy a battery can store at one time.
  • Lifespan: The length of time a battery can effectively be used before needing to be replaced.
  • Efficiency: How much usable energy is produced compared to the total energy input.
  • Depth of Discharge (DoD): How much of the stored energy can be used before impacting the battery’s performance.
  • Energy Density: The amount of energy a battery can store in relation to its size and weight.
  • Maintenance Requirements: How often and what types of maintenance are needed to keep the battery functioning properly.
  • Scalability: How easily a battery can be increased or decreased in capacity to meet changing energy needs.
  • Depth of Discharge (DoD): How much energy is cycled into and out of the battery on a given cycle. It's expressed as a percentage of the total capacity of the battery.
  • Round-Trip Efficiency: The percentage of electricity put into storage that is later retrieved. The higher the round-trip efficiency, the less energy is lost in the storage process.
  • Reliability: Battery reliability is often expressed as a culmination of factors, with the two most important being its useful service life, and the level of maintenance that you can expect to perform on the battery. 
  • Environmental Friendliness: One newer consideration is how environmentally friendly the battery is. Is it produced by a company known for using harmful practices? Does the battery have highly harmful substances like lead inside of it? Can you recycle the battery after it is no longer functional? All of these are important questions to consider before your purchase. Book a Solar Consultation today with a Spark Change customer success representative.

Your cart