Types of Solar Batteries: Pros & Cons and How to Choose?

A solar battery, also known as a solar panel battery or solar power battery is an energy storage device that is designed to connect with a solar charge controller for power backup and can be paired with a hybrid solar system. With a solar battery, you can store the extra power generated by your solar panels throughout the day and use it later as per your requirement.

The primary advantage of installing a solar battery storage system in your commercial or residential property is that it makes you competent to use your solar electricity even when the sun isn’t showing! When you get a solar panel system installed without a home solar battery, the excess electricity that is generated by your system gets redirected back to the grid. In case you get solar battery storage, that power can be retrieved and used when the sun goes down or the weather is cloudy and rainy.

Why battery storage plays an important role in solar applications?

A rechargeable battery is basically used to store the solar power generated by the solar panels and dismiss the power further as per requirement. The solar battery is made of nickel-cadmium, lithium-ion, or lead-acid, and it's fully rechargeable and can be used in solar cell systems to accumulate excess energy.

Places or applications wherein solar storage batteries are generally required include—solar charging stations, storage systems for power plants, and storage systems for off-grid. The usage of solar batteries in commercial and residential sectors makes the owner energy efficient and enhances their independence. When used in residential areas, it can minimize the functioning of grid power in small-scale applications. This approach can further cut down the monthly electricity bill and become the best option for consumers.

Solar battery storage: A smart concept

If you’ve been thinking about the key benefits of solar battery backups or solar battery storage systems, the below-mentioned five points will educate you about the same. For people who have solar panels installed at their residential properties, solar batteries can be an excellent energy saver way to stabilize their energy system and enjoy a reliable solar system for many years to come!

Power when you need it!

One of the biggest concerns with solar panels is that they are only able to produce electricity when there's the sun shining outside. Factors like—when you're not at home, clouds and shade, and rain can reduce the output of solar panels, leading your property to draw off the grid. With a home solar battery, the energy that your solar panels generate and that isn't used at the time of its generation gets stored. You can use the stored energy during nighttime or on those cloudy days without having to draw off the grid.

Energy security

The accessibility to store energy makes you less dependent on the grid for additional power need that may occur anytime. If you reside in a region that experiences frequent cloudy weather or has a crumbling energy infrastructure; solar battery storage can help shield you from the consequences of both bad weather and poor grid management. You gain self-sufficiency and control of your energy destiny. This proves to be the best option for people who are looking to get off the grid system.

Investment leading to long-term reliability

The investment in any type of energy storage system leads to long-term benefits and reliability in the coming future. Energy storage is a demanding nerve center for the entire grid system; amplifying resources from solar, wind, and hydro sources, to nuclear and fossil fuels, to demand-side resources and system efficiency equities. The solar battery storage system can act as a generation, transmission, and distribution asset—sometimes all combined in a single asset. Ultimately, the storage system is an empowering technology that can save property owners, industrialists and government money, improve their power reliability and flexibility, assimilate environment-friendly power generation sources, and minimize harmful environmental impacts.

Cut down electricity bills

The lesser the dependency on the grid, the lower is the electricity bill! Using rechargeable batteries results in the cutback of your energy bill because you will consume less energy from the grid. When you can easily store and use your own energy, the buyback is lesser than what the energy is sold for, leading to cost savings.

Better and safer for the environment

So far, the majority of electricity on the grid is generated through coal plants and other fossil fuels. Storing your energy lets you use the available environmentally friendly power with ease and at your convenience. Your solar power system will continue using minimal resources throughout the year while producing negligible to zero waste, zero noise pollution, and air/land deterioration. Because of advances in photovoltaic technology, panels create less pollution than fossil fuels during their lifetime usage.

Solar Battery System Statistics (2019 to 2027)

The worldwide solar battery market is segmented on the basis of end-user, type, and region. On the basis of type, it is divided into lead-acid, nickel-cadmium, lithium-ion, and flow battery. As per end-user, the market is classified into industrial, residential, and commercial. And lastly, region-wise, it is divided across North America, Europe, Asia-Pacific, and LAMEA. In 2019, the global solar battery market was worth $113.4 million, and is envisaged to reach $360.4 million by 2027; flourishing at a CAGR of 15.5% from 2020-2027. As governments worldwide are advocating maximum applications of sustainable energy sources, the demand and need for solar battery storage systems are expected to hike during the estimated timeframe! Furthermore, the rise in the amusement of industrialists toward renewable energy storage solutions is expected to acquire new investments in the coming years.

Solar Battery Market By Type

The lithium-ion section accounted for the maximum revenue share in the year 2019. This is because of the quick charge and discharge efficiencies of lithium-ion batteries, which further aids in accumulating a large amount of energy or power leading to longer usage. The average efficiency of lithium-ion batteries is 90-95%, whereas for lead acid it is around 80-85%. The improved lead-acid battery is projected as another advantageous segment in the future.

Solar Battery Market By End-User

In this graph, the industrial segment was marked for the highest revenue share in the year 2019. This is associated with the high demand from various industrial end-users for additional energy storage solutions in the form of battery storage systems. The residential segment remains the lowest revenue generator in both 2019 and 2027. Moreover, alluring new incentives and tax credit schemes from governments will further lure new end-users in this sector in the coming years.

What are the different types of solar batteries? (Pros and Cons)

There are four main varieties of solar storage batteries that are in use:

1. Nickel Cadmium (Ni-Cd) Batteries
2. Lead–Acid Batteries
3. Lithium-Ion Solar Batteries
4. Flow Batteries

Each of these batteries has some pros and cons when it comes to energy storage capacity, efficiency, maintenance, costing, and durability. Solar batteries are designed for solar systems and are different when compared to regular batteries. While each battery type has to meet certain safety and reliability specifications in order to be popular, sold, and installed in various segments—residential, industrial, and commercial sector; outside of those set standards, there is very minimal standardization of specs and features across these batteries which are available in the market today!

These solar batteries are increasingly popular in recent times as they are capable of fulfilling the world’s growing energy need along with negligible environmental impact. These batteries are specifically designed for solar systems with great features. So, without any further delay, let’s get deeper into the pros and cons of these solar batteries:

Nickel Cadmium (Ni-Cd) Batteries

This battery technology has been in use for over 100 years now, so it’s old tried and tested storage technology. Ni-Cd is relatively less costly when compared to newer battery types and has good specific energy as compared to technologies such as lead-acid. They are the best options for uninterruptible power supply and usage in generator-starting applications. The two features that have led to declining in Ni-Cd batteries demand are—do not get fully discharged before being recharged, and the battery starts losing its capacity / is very toxic to the environment.

Pros

• DoD (Depth of Discharge) – around 90%
• Energy Density – 50-150 Wh/L
• Efficiency – around 70%-85%
• Size – 1.2 volt rechargeable cells (exception – 9 volt size)
• Lifespan – longer life (1,000-2,000 cycles)
• Best Feature – ability to operate in extreme temperatures
• Maintenance – low maintenance is required because of simpler technology
• Price – less expensive as compared to other batteries

Cons

• Uses cadmium which is extremely toxic and harmful to the environment
• Limited charge holding capacity and storage space
• Not opt for small scale usage

Lead–Acid Batteries

These batteries have been tried and tested to store energy for a longer duration, and they’ve been in demand because of their reliability. As compared to modern rechargeable batteries, lead-acid batteries have low energy density. Lead-acid batteries represent one of the oldest rechargeable battery technologies and can be found in a wide variety of applications, which includes small-scale storage such as UPS systems, lighting, and ignition power for automobiles, as well as large/grid-scale power systems storage.

Pros

• DoD (Depth of Discharge) – Lead-acid (gel & AGM) batteries do not get discharged more than 30%-50% on a daily basis, unless in case of any emergency backup situation.
• Energy Density – 80-90 Wh/L
• Charge/Discharge Efficiency – 50%-85%
• Lifespan – 500-1,200 cycles
• Price – less expensive

Cons

• Has lower depth of discharge and thus, shorter lifespan
• Temperature-sensitive and requires ventilated areas for utmost performance
• Heavy in weight and takes lots of space

Lithium-Ion Batteries

Lithium-ion batteries are newer when compared to other battery types. Due to its technological advances, lithium-ion batteries have become one of the most widely used solar batteries in today’s era. Their temperature tolerance and environmentally safe feature make them popular and high in demand in today’s generation.

Pros

• Depth of Discharge (DoD) – Most modern lithium-ion batteries have a DoD ranging anywhere from 80% to 95%
• Charge/Discharge Efficiency – 80%-90%
• Lifespan – 500-2,000 cycles
• Maintenance – low maintenance
• Price – expensive
• Energy density – 100-265 Wh/kg

Cons

• It is more expensive than other energy storage technologies
• More prone to thermal runaway and catching fire (only if not installed properly)

Flow Batteries

These batteries are new in the solar storage solution and are in their development stage! Since it is water-based and doesn’t include the usage of any toxic metals, it’s certain that flow batteries will become more widespread in the coming years.

Pros

• DoD (Depth of Discharge) – almost 100% DoD, leading to maximum storage usage
• Energy density: 15-25 Wh/L
• Charge/discharge efficiency: 75-80%
• Lifespan – unlimited cycle life
• Maintenance – low maintenance
• Environmental impact – water-based and completely non-toxic in nature

Cons

• Its technology advancements are still in the early stages
• It is expensive as compared to other batteries
• Low charge and discharge rates

How to decide which battery specs are best as per your needs?

There are a number of different decision criteria and comparison points to go through while evaluating your energy storage options. Below are a few common decision criteria and battery specs that matter the most if these criteria match your situation:  

• Residential usage – recently, lithium-ion batteries have surged in popularity over lead-acid batteries as the preferred option for home solar storage because of their longer lifespan, more energy storage capacity, and efficiency.
• Larger off-grid systems – lead-acid batteries are one of the most trusted and used options since it is a correctly designed system, which can typically last for around 10-15 years or even longer.
• Best battery type for off-grid solar systems – Lithium and AGM batteries
• Best battery system for solar-powered street lights – Lead-acid battery storage system
• Best battery type for solar garden lights or solar-powered gadgets – LiFePO4 batteries 
• Longer lifespan needed – If you want a battery system with the longest lifetime then you can use a maximum amount of times, opt for lithium iron phosphate (LFP) batteries.
• Less space available – If you have space constraints and want maximum storage out of the least available space, go for lithium-ion nickel manganese cobalt (NMC) batteries.
• Looking for maximum safety – If you want a battery storage system with the highest safety rating, look to LFP batteries.

Things to consider while purchasing the best solar battery

One of the most vital aspects is to know everything about solar batteries and the type of usage you need from them after installation. To make things easier for you below are a few points that you need to consider while making a solar battery purchase:

• Storage capacity, efficiency – To find the best-fitted size system for your usage, you should know beforehand the storage capacity of the battery type that you are planning to purchase. Be mindful, batteries come with total capacity and usable capacity specifications. Always prefer a battery storage system with maximum efficiency, capacity, and DoD.
• Battery type, lifespan, and degradation – When searching for the best type of solar storage batteries to buy, there are a couple of alternatives/options available and currently in demand in the market. Each battery type has its own advantages and disadvantages, so opt for the one that has a larger lifespan and battery cycle.
• Both product and performance warranty – Being aware of how long your battery will last is very important. The lifespan of a battery type can be covered in a product warranty, which is very crucial. As solar batteries are expensive and an investment that you make, you need to be extra careful about going through the entire product and performance warranty cards and specifications before finalizing a battery type.
• General specifications – Apart from the above-mentioned points, you also need to consider the weight, size, environmental impact, and future maintenance cost which is involved in the battery system you are planning to invest in! Think upon every point in detail and finalize the battery system that suits your budget, usage, and requirement perfectly.

Conclusion

The answer to the question, “Which is the best solar battery for storage?” is not as easy as you think, because every battery comes with a few pros and cons that needs to be juxtaposed. Before you settle on a solar battery storage system which is perfect as per your needs, you should keep in mind the four key solar battery aspects - Capacity and Power, Depth of Discharge, Round-Trip Efficiency, and Warranty.

The vital features of the battery you choose will further determine how long your solar batteries will last, and what battery life should be expected! For example, how fast the capacity rating of the battery slashes will determine how long it can be used before the need for replacement. A typical home solar battery system possesses a battery life between 5-15 years before the battery performance starts deteriorating.