Introduction
Solar panels allow you to generate your own electricity and can reduce your utility bills, but they won’t do so at night or during a power outage. But a solution to both issues is getting more common and more affordable.
Solar batteries can be a valuable part of a residential solar system. They provide reliability, safety, economic benefits, and comfort for your family. Batteries allow you to use solar power 24/7, maximize savings from your system, and have reliable power during bad weather and grid outages.
If you’re looking for the answer to “How do solar batteries work?” This article will explain what a solar battery is, solar battery science, how solar batteries work with a residential solar power system, and the overall benefits of energy storage within your own system.
What is a Solar Battery?
A solar battery is an energy storage system designed to harness excess electricity generated by your solar panels. Unlike conventional power usage which requires immediate consumption, solar batteries store this electricity for later use.
This functionality extends the utility of solar panels beyond sunny hours, allowing them to provide clean, renewable energy around the clock. Whether it’s during cloudy days, after sunset, or amidst power outages, solar batteries ensure continuous energy independence and enhance overall system efficiency.
The Science of Solar Batteries
Lithium-ion batteries are the most popular form of solar batteries on the market. This is the same technology used for smartphones and other high-tech batteries.
Lithium-ion batteries work through a chemical reaction that stores chemical energy before converting it to electrical energy. The reaction occurs when lithium ions release free electrons, and those electrons flow from the negatively charged anode to the positively charged cathode.
This movement is encouraged and enhanced by lithium-salt electrolyte, a liquid inside the battery that balances the reaction by providing the necessary positive ions. This flow of free electrons creates the current necessary for people to use electricity.
When you draw electricity from the battery, the lithium ions flow back across the electrolyte to the positive electrode. At the same time, electrons move from the negative electrode to the positive electrode via the outer circuit, powering the plugged-in device.
Home solar power storage batteries combine multiple ion battery cells with sophisticated electronics that regulate the performance and safety of the whole solar battery system. Thus, solar batteries function as rechargeable batteries that use the power of the sun as the initial input that kickstarts the whole process of creating an electrical current.
Types of Solar Batteries
Various types of batteries can support your solar power system, each with distinct advantages and considerations.
Lead-Acid Batteries
Lead-acid batteries are a traditional choice in both automotive and solar energy applications, known for their cost-effectiveness and reliability. These batteries offer a lower energy density, which means they are heavier and bulkier for the energy they store. However, they are economically viable and robust.
Available in both flooded and sealed versions, lead-acid batteries are designed for either shallow cycle or deep cycle applications, with recent advancements extending their usable life significantly.
Lithium-Ion Batteries
Lithium-ion technology represents a more recent development in battery technology, known for its high energy density and efficiency.
These batteries are lighter and more compact, capable of storing more energy with less physical footprint, making them ideal for home energy systems as well as portable electronics. The main drawback is their higher cost. Additionally, they must be carefully managed to avoid risks such as thermal runaway.
Nickel-Cadmium Batteries
Nickel-cadmium batteries are less common in residential settings but are favored in applications that demand high durability and performance under extreme conditions.
They are extremely robust, perform well under a wide range of temperatures, and require minimal maintenance.
Flow Batteries
Flow batteries utilize a different mechanism involving two liquid electrolytes flowing through the system to produce energy.
They are known for their high efficiency and the ability to discharge completely without damaging the battery’s lifespan. Despite their benefits, the large size and infrastructure required to house the electrolyte liquids make flow batteries less practical for residential use and more suited to larger, industrial applications.
By understanding the specific attributes and suitable applications of these battery types, homeowners can make informed decisions about which battery technology best meets their needs.
AC-Coupled Storage vs. DC-Coupled Storage
Coupling refers to how your solar panels are wired to your battery storage system, and the options are either direct current (DC) coupling or alternating current (AC) coupling. The main difference between the two lies in the path taken by the electricity that the solar panels create.
Solar cells create DC electricity, and DC electricity must be converted into AC electricity before it can be used by your home. However, solar batteries can only store DC electricity, so there are different ways of connecting a solar battery into your solar power system.
DC-Coupled Storage
With DC coupling, the DC electricity created by solar panels flows through a charge controller and then directly into the solar battery. There is no current change before storage, and conversion from DC to AC only occurs when the battery sends electricity to your home, or back out into the grid.
A DC-coupled storage battery is more efficient, because the electricity only needs to change from DC to AC once. However, DC-coupled storage typically requires a more complex installation, which can increase the initial cost and lengthen the overall installation timeline.
AC-Coupled Storage
With AC coupling, DC electricity generated by your solar panels goes through an inverter first to be converted into AC electricity for everyday use by appliances in your home. That AC current can also be sent to a separate inverter to be converted back to DC current for storage in the solar battery. When it’s time to use the stored energy, the electricity flows out of the battery and back into an inverter to be converted back into AC electricity for your home.
With AC-coupled storage, electricity is inverted three separate times: once when going from your solar panels into the house, another when going from the home into battery storage, and a third time when going from battery storage back into the house. Each inversion results in some efficiency losses, so AC-coupled storage is slightly less efficient than a DC-coupled system.
Unlike DC-coupled storage that only stores energy from solar panels, one of the big advantages of AC-coupled storage is it can store energy from both solar panels and the grid. This means even if your solar panels aren’t generating enough electricity to fully charge your battery, you can still fill the battery with electricity from the grid to provide you with backup power, or to take advantage of electricity rate arbitrage.
It’s also easier to upgrade your existing solar power system with AC-coupled battery storage, because it can just be added on top of an existing system design, instead of needing to be integrated into it. This makes AC-coupled battery storage a more popular option for retrofit installations.
How Solar Batteries Work with a Solar Power System
This entire process starts with the solar panels on the roof generating power. Here is a step-by-step breakdown of what happens with a DC-coupled system:
- Sunlight hits the solar panels and the energy is converted to DC electricity.
- The electricity enters the battery and is stored as DC electricity
- The DC electricity then leaves the battery and enters an inverter to be converted into AC electricity the home or the grid can use.
The process is slightly different with an AC-coupled system.
- Sunlight hits the solar panels and the energy is converted to DC electricity.
- The electricity enters the inverter to be converted into AC electricity the home can use.
- Excess electricity then flows through another inverter to change back into DC electricity that can be stored for later.
- If the house needs to use the energy stored in the battery, that electricity must flow through the inverter again to become AC electricity.
How Solar Batteries Work with a Hybrid Inverter
If you have a hybrid inverter, a single device can convert DC electricity into AC electricity and AC electricity into DC electricity. As a result, you don't need two inverters in your photovoltaic system: one to convert electricity from your solar panels (solar inverter) and another to convert electricity from the solar battery (battery inverter).
Also known as a battery-based inverter or hybrid grid-tied inverter, the hybrid inverter combines a battery inverter and solar inverter into a single piece of equipment. It eliminates the need to have two separate inverters in the same setup by functioning as an inverter for both the electricity from your solar battery and the electricity from your solar panels.
Hybrid inverters are growing in popularity because they work with and without battery storage. You can install a hybrid inverter into your battery-less solar power system during the initial installation, giving you the option of adding solar energy storage down the line.
Why You Need a Solar Battery
Adding battery backup for solar panels is a great way of ensuring you get the most out of your solar power system. Here are some of the main benefits of a home solar battery storage system.
1. Stores excess electricity generation
Your solar panel system often produces more power than you need, especially on sunny days when no one is at home. If you don't have solar energy battery storage, the extra energy will be sent to the grid. If you participate in a net metering program, you can earn credit for that extra generation, but it’s usually not a 1:1 ratio for the electricity you generate.
With battery storage, the extra electricity charges up your battery for later use, instead of going to the grid. You can use the stored energy during times of lower generation, which reduces your reliance upon the grid for electricity.
2. Provides relief from power outages
Since your batteries can store the excess energy created by your solar panels, your home will have electricity available during power outages and other times when the grid goes down.
3. Reduces your carbon footprint
With solar panel battery storage, you can go green by making the most of the clean energy produced by your solar panel system. If that energy isn't stored, you will rely on the grid when your solar panels don’t generate enough for your needs. However, most grid electricity is produced using fossil fuels, so you will likely be running on dirty energy and boosting your personal carbon footprint when drawing from the grid.
4. Provides electricity even after the sun goes down
When the sun goes down and solar panels aren't generating electricity, the grid steps in to provide much-needed power if you don’t have any battery storage. With a solar battery, you’ll use more of your own solar electricity at night, giving you more energy independence and helping you keep your electric bill low.
5. Provides quiet backup power
A solar power battery is a 100% noiseless backup power storage option. You get maintenance-free clean energy, without the noise from a gas-powered backup generator.
How Solar Secure Can Help You
Solar Secure specializes in installing solar batteries, offering expert consultations to identify the best solutions tailored to your energy requirements. We assist with system design to ensure compatibility with your existing solar setup, guide you through the installation process, and help with permits and available incentives or rebates. Our expertise guarantees a system optimized for efficiency, safety, and long-term performance.
Our solar batteries are renowned for their high storage capacity, durability, and long lifespan, delivering reliable and uninterrupted power. To ensure top quality, we collaborate with leading brands in the solar industry.
At Solar Secure, we guarantee peak performance from day one by not only installing solar panels, batteries, and inverters but also thoroughly testing and verifying integrations at every stage of the process.
Conclusion
Understanding how a solar battery works is important if you’re thinking about adding solar panel energy storage to your solar power system. Because it operates like a large rechargeable battery for your home, you can take advantage of any excess solar energy your solar panels create, giving you more control over when and how you use solar energy.
Lithium-ion batteries are the most popular type of solar battery, and work through a chemical reaction that stores energy, and then releases it as electrical energy for use in your home. Whether you choose a DC-coupled, AC-coupled, or hybrid system, you may be able to increase the return on investment of your solar power system and reduce your reliance on the grid.