If you’ve decided to invest in a residential solar panels, you want to make sure that you get as much out of it as you can. However, solar systems don’t have a built-in way to utilize excess energy. In other words, if your panels create more energy than you need for your home, that extra energy will go to waste.
Solar energy storage is a field that’s designed to address this problem. Its purpose is to help make solar panels more efficient by capturing the excess energy they produce and storing it for later use.
In this article, we’ll cover everything that you need to know about solar energy storage for your home system. Keep reading to learn about:
- What solar batteries are and how they work
- Why you might consider adding a solar panel battery to your system
- Alternative solar energy storage options
Why solar energy storage matters
Solar energy storage is important because it aims to fix one of the biggest weaknesses of solar systems. This weakness is the fact that solar systems have no built-in way to utilize any excess power they generate. Without solar energy storage, panels would only have limited usefulness since people would only be able to use them when the sun was out.
In this way, solar energy storage increases the usefulness of solar systems. Storage also makes solar systems a viable option for people in various geographic locations since it lets people use the solar energy they generate even when the sun isn’t shining.
What is a solar battery?
Solar batteries are the main device used for solar energy storage. These are essentially rechargeable batteries (often made out of lithium-ion) that take in the extra energy that a set of solar panels generates during the day.
Homeowners are then able to pull solar power from their batteries during the evening or at other times when the sun isn’t shining but they still need power. This replaces the need to have to pull electricity from the utility grid to power your home -- at least until all of the charge in the solar battery is used up.
How solar battery storage works
The solar battery storage process is fairly self-explanatory at a broad level. Your solar panels generate excess power during some parts of the day. That extra power gets sent to the solar battery. And then you can use it to power your home whenever you want.
The way that this works from a technical perspective varies based on the type of battery that you have. For example, most modern solar batteries are made out of lithium-ion.
Lithium-ion solar batteries work by sending lithium ions through the electrolytes that get transferred from your solar panels to the battery. This process creates electrons, which is what makes up the actual power that the battery stores. These electrons get sent through your home’s energy grid when needed to provide you with power.
Benefits of adding a solar panel battery to your system
There are lots of good reasons to add a solar panel battery to your system. But here are three of the most important.
Most people who add a solar battery to their home do so because they see it as a good financial investment. Solar batteries save you money by reducing the amount of electricity that you need to pull from the utility grid. This brings down your electricity bill and may even be enough to eliminate it entirely.
Solar batteries can last up to 15 years, which means adding one to your system could provide you with more than a decade of savings.
Reduce your carbon footprint
Solar batteries also help a homeowner bring down their carbon footprint by more than they can do with a solar system alone. Once again, solar batteries achieve this by reducing your need to pull electricity from the utility grid.
That means with a solar battery, you’ll be less reliant on fuel-generated sources of energy and able to use a cleaner source of power for a greater portion of your home’s total energy needs.
Increase your energy independence
Solar batteries are also great for people who are looking for energy independence. Batteries are commonly used with off-grid solar systems because they provide a backup source of power that can be used when the sun isn’t shining. In this way, solar batteries enable people who want to live an off-the-grid lifestyle to do so in a more comfortable, reliable way.
How much does installing a solar battery cost?
The amount that you pay to install a solar battery can vary a good deal based on factors like which battery you choose, who you ask to install it, and where you’re located. That being said, the average cost of a solar battery storage system in the United States is between $7,000 and $14,000.
When solar backup batteries make sense
Solar backup batteries make a great addition to most residential solar systems since they allow you to use the excess energy that your panels generate at a later time. However, batteries aren’t the only way to benefit from the extra energy that your panels create.
Net metering can be a viable alternative to solar batteries for many consumers. This is a billing practice that essentially involves sending your excess solar energy into the utility grid in exchange for a credit that reduces your electricity bill.
For example, if you sent 10 kWh of power into the grid, you would receive either a discount or no charges for 10kWh of electricity that month. In that way, you get to enjoy the financial benefits of generating excess solar energy without having to add a battery to your system.
However, net metering increases your reliance on the utility grid instead of decreasing it. Additionally, the utility company may not credit you for excess energy at the same kWh rate that it charges you for electricity. That means you may not save as much with this option.
The process of adding a battery backup to your system
Many people choose to install a solar battery during their initial setup. But you also have the option of doing so after your system has already been installed.
The difficulty of this will depend on the specifications of your system. Many modern solar panel systems are “storage ready”. This means they have inverters that you can add a solar battery to with ease.
Generally, the process of adding a battery backup to your system is fairly straightforward. You simply call up a solar installer and have them come out to take a look at your system. They can then recommend a battery option that will suit your needs.
Once you’ve selected the battery that you’re going to use, the installer will need about a full day to integrate it into your broader solar energy system.
AC vs DC-coupled solutions
If you decide to add a solar battery to your system after it’s already been installed, this is one decision you’ll need to make. AC-coupled batteries involve adding a second inverter to your system instead of replacing your old one. This can save you some money upfront but will result in some added inefficiencies.
The alternative is to go for a DC-coupled solution. This involves replacing your inverter entirely with a battery-tied inverter system. This costs a bit more upfront but is more efficient. Both options are viable. It really just depends on whether you prefer upfront savings or long-term efficiency.
The cost of solar panels with a battery backup
Adding a solar battery to your system can either be very cheap or quite expensive. The price range for installing a new solar battery can range from as low as $200 to as much as $15,000.
That being said, most homeowners will end up paying $7,000 to $14,000 to add a solar battery to an existing system as this is the average cost for installing a lithium-ion battery to a grid-tied solar system.
There are lots of factors that can impact the total price you pay for this. For example, your location, the solar battery that you select, and the installer that you decide to go with can all influence the overall amount you pay for a solar battery installation.
Does everyone need a solar panel battery?
You don’t necessarily need to have a solar panel battery installed with your solar system, as doing so can be expensive. Additionally, you may live in an area with a solid net metering policy that offers similar savings.
However, if you really want to maximize what you get from your solar panels, investing in a solar panel battery is the best way to do it. With a solar battery, you will enjoy greater savings while also reducing your carbon footprint and increasing your energy independence.
That being said, one thing to keep in mind is that solar battery technology is constantly improving. It’s likely that prices will go down in the coming years. So if you’re not convinced that you need a solar battery right this minute, then waiting to buy could be a profitable decision.
Going “off-grid” with a solar system with batteries
Solar batteries are also a good investment for homeowners who are interested in moving their home energy system off of the grid entirely. If you don’t want your home to be connected to the electrical grid, then you need a way to keep the lights on at night. Solar batteries provide that.
They can play a big role in helping you get the energy independence that you have been looking for. You can even install multiple solar batteries on your property to give yourself a bigger store of energy in case your solar panels aren’t able to generate as much power as they normally do for a few days.
Net metering as a solar battery alternative
If you aren’t interested in disconnecting your home from the electrical grid in your area, then net metering is an alternative to solar batteries that you may want to look into. It’s an electrical billing practice that gives you credit based on how much energy you send back into the grid.
Both net metering and solar batteries deal with the excess energy that your panels produce. With net metering, that energy gets sent back into the electrical grid instead of stored in a battery.
The result is the same for you from a financial perspective: you save money by getting credit off your electricity bill for the excess solar energy that you produce.
However, the exact amount of money that you save from net metering may not be as much as you could save by adding a solar battery to your system. Additionally, net metering doesn’t allow you to go off-grid and it doesn’t help you improve your energy security or fight back against demand charges like solar batteries do.
Factors to consider while looking for the best solar battery
There’s a lot to think about before settling on a solar battery for your system. Here are five factors that should play a role in your decision-making process.
Capacity is the measurement of how much energy a solar battery is able to store at a given time. It’s tracked in kilowatt-hours (kWh). The more kWh that a battery has, the more solar energy that you can store in it and use later to power your home.
Generally, you have to pay more for batteries with larger capacities. That’s because these batteries enable you to pull less energy from the grid, thereby reducing your electricity costs.
A solar battery’s power rating is a measurement that shows how much power it’s able to put out at once. It’s measured in kilowatts or Amps. The greater a battery’s power rating is, the more appliances, lights, and electronics that it will be able to power at once.
You might see two different power ratings while comparing solar batteries for homes. A battery’s continuous power rating shows the maximum amount of power that it can put out over a long time frame. A battery’s instantaneous power rating shows the maximum output it can achieve for five minutes.
Cost is a factor that needs no introduction. But when it comes to solar batteries, what you’re looking for in terms of cost isn’t necessarily to get the lowest price possible. Instead, you want to find the best value at a price point that you’re comfortable with.
For example, you might be okay with spending up to $10,000 on a solar battery. If so, you would want to compare the power ratings, capacities, and other key aspects of each battery that you’re looking at. Then pick the one that offers the most bang for the buck instead of trying to just pay as little as possible.
Depth of discharge
Depth of discharge is the percentage that a solar battery can be discharged in relation to its total capacity.
For example, imagine a solar battery has a capacity of 10 kWh. That doesn’t necessarily mean you can access the entire 10 kWh of power. Instead, you may only be able to access 8 kWh of the energy. If so, the battery would have a depth of discharge of 80%.
Solar batteries don’t discharge all of their energy because doing so would shorten their lifespan by quite a lot. There’s a balance here.
The lifespan of a solar battery will play a huge role in determining whether purchasing one will be a smart investment for you. The lifespan of solar batteries is often measured in three different ways: expected years of operation, expected throughput, and expected cycles.
A battery’s expected years of operation is a fairly self-explanatory metric. It measures how many years you can expect to use the battery.
A battery’s expected throughput refers to how much electricity you can move through the battery throughout its lifetime. This can be useful to keep track of if you think that you use a lot more or a lot less energy than the average solar battery owner.
Finally, a battery’s expected cycles is a metric that refers to how many times you will be able to charge and discharge a battery throughout its lifespan. To get the most comprehensive picture of how long a particular solar battery will last, it’s best to consider all three of these measurements in combination with one another.
Solar battery reviews
Reviews of individual solar batteries can be a useful way to learn more about how they work in practice. However, when you’re reading solar battery reviews, make sure that you’re not reading too heavily into any single review.
Instead, you will want to look for trend lines that keep coming up in reviews from different people. Focusing on these will help you get the most accurate representation of what using the battery would be like for you.
Solar battery types
There are four major types of solar batteries that you might see while shopping for one. You can check out our page on how solar batteries work to get a complete overview of each of them.
For this article, it’s enough to know that lithium-ion batteries are the most common. This is because they offer an excellent blend of efficiency, affordability, and ease of use that other types of solar batteries on the market can’t match right now.
As a point of reference, here are the four major types of solar batteries:
- Sodium Nickel Chloride
Most popular brands for solar batteries for home
There are lots of different solar battery brands on the market today. But the following three are chosen by U.S. consumers most often for their strong blend of product quality, affordability, and brand trust.
Tesla’s Powerwall is the most known solar battery on the market. Part of that is because of how popular Tesla is as a company. But the battery itself is also really good.
The Powerwall is an AC battery that has a large capacity of 13.5 kWh. This is more than enough than the average household will need. That being said, purchasing the latest edition of the Powerwall (the Powerwall 2) will set you back about $10,500, which is pretty expensive for a solar battery.
Additionally, Tesla’s Powerwall is currently hard to get your hands on. The company is currently only selling them to customers who are also getting solar panels installed. Check out our Tesla Powerwall battery review.
LG is one of the biggest electronics brands in the world. It has built up a ton of trust among consumers by consistently producing solid, affordable products. The company’s LG Chem RESU solar battery follows this trend.
The battery is available in three different sizes: 6.5 kWh, 10 kWh, and 13 kWh. It features an impressive 90% usable capacity and 5kW of continuous power. Even better, you can purchase one for as little as $6,400, which is super affordable for a high-quality solar battery. Check out our LG Chem battery review.
Sonnen is a German company that is quickly becoming one of the largest players in the home solar battery market. The company sells three different types of solar batteries: SonnenCore, Sonnen EcoLinx, and Sonnen Eco.
These offer scaling power, capacity, and prices, which makes it pretty easy for any homeowner to find a product from Sonnen that fits their budget and home energy needs. Check out our Sonnen battery review.
Do solar panels need batteries?
Given all of the benefits offered by solar batteries, you might be asking yourself this question. You technically don’t need a battery with your solar energy system. It is perfectly fine to run your system without worrying about the excess power that it generates. You will still save money on your energy bill and reduce your home’s carbon footprint.
However, if you want to get as much out of your solar system as possible, you need a way to harness the excess power that it generates. Batteries are one of the most popular and easy ways to do that. But net metering will also do the job if you don’t want to have to spend a lot of money on adding a solar battery to your system.
A final word on solar with battery
Adding a battery to your solar system is one of the most effective ways to take full advantage of the excess power that it generates. Most people who add batteries to their systems will save enough money on their energy bills to make the relatively high upfront cost of a battery worth it.
That being said, if you don’t care as much about energy independence or going off-grid, net metering can be a viable alternative to a solar battery. It will also help you save money by utilizing your excess solar energy instead of allowing it to go to waste.
Solar panels with battery backups: FAQs
How long do solar batteries last?
Solar batteries tend to last between 5 and 15 years. That means you may eventually need to replace yours at some point during the lifespan of your system.
How long can a solar battery power my home?
The exact length of time will depend on the strength and quality of the solar battery that you install. But a good estimation is between 10 to 15 hours if the battery is fully charged.
Can I install a solar battery myself?
You can complete the installation yourself but you should only do so if you know what you’re doing, as the process can be pretty complicated for a novice.
How do you maintain solar batteries?
The best way to ensure your solar battery lasts as long as possible is to take good care of it. That means cleaning the terminal regularly with a mixture of baking soda and distilled water. You may also want to coat the metal components with a sealant to promote efficiency.
What happens when solar batteries are full?
When solar batteries are full, any excess energy that your panels create will either be wasted or sent into the utility grid if you’re participating in a net metering program.
Can you overcharge a battery with a solar panel?
Most modern solar batteries have built-in solar charge controllers that prevent this from happening. But if yours doesn’t, you will want to make sure that you have one installed to prevent overcharging from occurring, which can damage your batteries and reduce their lifespans.