Solar Panel Battery Storage
What is a solar battery?
A solar battery is an essential component of any home solar power system. It’s a system that you can connect to your solar energy set up to store the excess power generated by your panels.
How does solar battery storage work?
A battery will transform DC power from your solar panels into AC power and store it, ready for use later when your solar panels produce electricity that you don’t need to utilize straight away.
In other words, when you don’t require the electricity produced by your solar panels, they charge the battery, which then supplies power to your home when your solar panels aren’t producing enough electricity, such as at night, on overcast days, and during power cuts.
What are solar storage batteries made of?
The type of solar batteries you’ll see on the market will usually be lithium-ion batteries.
These batteries are becoming increasingly popular as they’re more lightweight and have a higher energy density than lead-acid batteries (which were once the most popular option).
Related: Solar Advantages and Disadvantages
The Science of Solar Batteries
The most popular form of solar batteries available is lithium-ion batteries. This is the same technology utilized in smartphones and other high-tech batteries.
Lithium-ion cells work by allowing electrons to flow from the negatively charged anode to the positively charged cathode as a result of a chemical reaction.
Lithium-salt electrolyte is a liquid that balances the reaction by providing the necessary positive ions, thus promoting and encouraging this movement.
This constant flow of free electrons provides electricity for people to utilize. When you pull electricity from the battery, lithium ions flow back across the electrolyte to the positive electrode.
At the same time, electrons move from the anode through your device to the cathode.
Solar power batteries are a type of self-contained rechargeable battery built from several ion battery cells and sophisticated technology that controls the performance and safety of the entire solar battery system.
As such, solar batteries operate as rechargeable batteries that require sunlight to start the whole process of converting light into electricity.
Comparing Battery Storage Technologies
The most popular solar battery types are lithium-ion and lead-acid. Solar panel manufacturers prefer lithium-ion batteries because they can retain more energy, store it for longer than other batteries, and have a greater Depth of Discharge.
The DoD, or Depth of Discharge, is the proportion to which a battery can be utilized when compared to its total capacity.
If a battery has a DoD of 95%, it may safely use up to 95% of the battery’s capacity before needing to be recharged.
A lithium-ion (Li-ion) battery is a sophisticated type of battery that uses lithium ions as part of its electrochemical mechanism.
Lithium atoms in the anode are ionized and separated from their electrons during a discharge cycle.
Lithium-ion battery technology is preferable for deep discharge operations because it offers greater DoD, longer lifespan, more energy density, and smaller size.
With all of these advantages, lithium-ion batteries are also more expensive than lead-acid batteries.
The negative electrode of a lead-acid battery is made of spongy or porous lead. The lead is porous to allow for the formation and dissolution of metal.
Lead oxide is used in the construction of the positive electrode.
Both electrodes are immersed in a mixture of sulfuric acid and water known as an electrolyte.
In order to reduce the chance of shorting between the two electrodes, a chemically permeable but electrically insulating barrier is placed between them as a result of the physical movement of the battery or changes in electrode thickness.
This membrane also prevents electrical shorting through the electrolyte by preventing current from reaching its intended destination.
AC Coupled Storage vs. DC Coupled Storage
Solar panel mounting and connection are two different things. DC or AC coupling is how your solar panels are linked to your battery storage system, and there are two choices: direct current (DC) couplings or alternating current (AC) couplings.
The main distinction between the two is in the electricity’s route.
Solar cells convert direct current (DC) into alternating current (AC), which must then be converted to household AC electricity before it may be utilized.
Solar batteries, on the other hand, can only store DC energy and so need to be connected in a variety of ways depending on your solar power system.
DC Coupled Storage
The DC system is connected to your solar panels right before your generation meter.
A charge controller in a DC-coupled system receives Direct Current from your solar panels and joins the battery system.
Any electricity generated by your solar panels will only be reversed once from DC to AC, at either the point where the current travels from your battery to your home or the National Grid.
AC Coupled Storage
AC electricity travels from your solar panels to an inverter in an AC-coupled system. An inverter transforms DC power into AC power that can be used by your home.
If this energy isn’t required, it is sent to another inverter, which changes it back into DC for storage in your solar battery.
When this energy is needed, it is converted back into AC so it can be used in your home.
AC-coupled systems are considered more reliable and provide additional features that may be appealing, such as the ability to monitor your system’s electricity usage and generation remotely.
How Solar Batteries Work with a Solar Power System
The solar panels on the roof produce electricity, which is then converted into alternating current by your inverter.
Here’s a breakdown of how a DC-coupled system works:
- The solar panels convert sunlight into DC electricity, which is stored in the battery.
- The battery receives energy and stores it as DC electricity.
- After leaving the battery, the DC power goes through an inverter to be changed into AC electricity that can be used by the home.
With an AC-coupled system, the procedure is somewhat different:
- The solar panels absorb energy from the sun and convert it to direct current.
- The electricity is sent to the inverter, which transforms it into usable AC electricity.
- Extra power is passed through an inverter to transform it back into DC power that can be stored for later use.
- If the house requires access to the energy stored in the battery, electricity must be transformed back into AC power by the inverter so it can be used.
Related: How Do Solar Panels Generate Electricity?
How Solar Batteries Work with a Hybrid Inverter
A hybrid solar inverter can transform DC into AC while also sending any extra power to be stored in a solar battery or sold to the grid.
When required, the power may then be inverted to AC and utilized inside your home.
You can use a single device to convert DC electricity into AC electricity and vice versa if you have a hybrid inverter.
As a result, you don’t need two inverters in your photovoltaic (PV) system: one to convert power from your solar panels (solar inverter) and another to transform energy from the solar battery into AC electricity (battery inverter).
The hybrid inverter is a type of battery-based inverter or grid-tied hybrid inverter that combines a solar inverter and a battery inverter into a single piece of equipment.
By functioning as an inverter for both your solar battery electricity and your solar panels, it eliminates the requirement for two separate inverters in the same system.
Hybrid inverters are becoming increasingly popular because they may be used with or without battery storage.
During the first installation, you may install a hybrid inverter into your battery-free solar power system, allowing you to add solar energy storage at a later time.
Domestic and Commercial Use Cases
Domestic solar battery storage systems
A domestic solar battery storage system is much different from a commercial or industrial application.
The most important distinction is the amount of power that is required and, as a result, the size of the battery.
Storage systems like the Tesla Powerwall are designed for the residential market and can provide a maximum of 5kWh of power.
This is enough to run some homes for several hours, but it’s not nearly enough for commercial applications.
The systems are also designed to work with existing solar PV arrays, so you don’t need to install new panels if you want to add storage capacity.
Commercial solar battery storage systems
Solar batteries for commercial or industrial applications tend to be much larger than domestic systems.
They are often used in conjunction with diesel generators or other forms of backup power to provide a constant supply of electricity.
In some cases, they are used as part of a microgrid that can disconnect from the main grid and operate independently.
The most popular form of system is a solar farm. Solar parks and solar power stations are alternative names for them.
They function similarly to traditional fossil-fueled power plants, although they are more efficient in converting sunlight into electricity.
A solar farm is a large-scale photovoltaic system that is designed for business use. They’re frequently employed by utilities as an environmentally friendly alternative to coal and natural gas power plants.
How do Solar Batteries Work with Microgrids?
Solar batteries can be used in conjunction with microgrids. A microgrid is a small-scale power grid that can operate independently of the main grid.
Microgrids are often used by businesses and organizations that need to ensure a reliable supply of electricity, such as hospitals or data centers.
Solar batteries can provide power to a microgrid when the sun is shining, and other forms of backup power can be used when the sun is not shining.
What does ‘utility-scale solar’ mean?
Utility-scale solar refers to large-scale solar power plants that are designed to provide electricity to a utility grid.
These plants are usually owned and operated by utilities, although there are a growing number of projects that are owned by independent power producers.
What is the difference between a ‘solar battery’ and a ‘solar panel’?
A solar panel is a device that converts sunlight into electricity. Solar batteries are devices that store electricity generated by solar panels for later use.
Solar batteries can be used in conjunction with solar panels to provide a reliable source of electricity, even when the sun is not shining.
How much battery do I need for off-grid solar?
If you want to keep the power on when the grid goes down, a single solar battery will usually be enough. You’ll need considerably more storage capacity if you wish to go entirely off-grid, such as 8-12 batteries.
How long do solar batteries last?
Solar batteries have a lifespan of 5-15 years. This is much longer than the average car battery, which only lasts for 3-5 years.
Are solar batteries worth it?
Solar batteries can provide a number of benefits, including backup power, reduced dependence on the grid, and lower electricity bills.
However, they also come with a significant upfront cost. As such, solar batteries are not right for everyone.
You should only consider solar batteries if you are confident that you will be able to recoup the initial investment through savings on your electricity bill.
What are some of the challenges with solar battery storage?
The most significant challenge with solar battery storage is the high upfront cost. Solar batteries are still a relatively new technology, and the price has not yet come down to a level that is affordable for most consumers.