How to Choose the Right Batteries for Solar Panels

batteries for solar panels

There are many good reasons to switch to solar energy right now. It’s better for the environment and helps you save money, and it also helps you be less reliant on your local power grid.

But what happens when the sun goes down? What happens if there’s a power outage on your block and your solar panels can’t produce energy?

There are batteries for solar panels that can help produce backup power in an emergency. You just need to know which one to get for your system.

Read on to learn how to choose the best solar batteries for your home’s system.

Why Do You Need Batteries for Solar Panels?

The whole idea of getting a solar power system for your home is to generate your own power. This helps protect the environment because it’s a clean energy source. It also lowers your energy bill every month.

The singular issue that comes with this is that solar panels can only create energy when the sun is shining on them, but most people don’t stop using electricity as soon as the sun goes down. So what happens at night when the Sun’s not out? 

If you don’t have a battery on your system, then your electric company will usually take over from here. They may also buy back the extra energy from your system that you never used during the day.

The problem is that if there’s a power outage at night then your household is out of luck. Even during the day, there can be heavy storms that knock out your power and your solar panels’ ability to create energy for a while. This is why having a battery is so important. 

A solar battery is charged by the unused energy created by your solar panels during the day. That means that at night and during power outages, your house will still have power to it because of the solar batteries.

Type of Battery

The first thing you need to consider when choosing a battery system for your solar panels is the type of battery you want. There are different kinds of batteries that each have their own benefits and issues, so the kind you want is going to depend on the concerns you have for your system.

In general, most people will probably want either a lead-acid or a lithium-ion battery system on for their systems. These are the two most popular and most reliable battery types right now. However, new types of batteries are always being experimented with.

In general, lithium-ion batteries are going to be lighter and provide more energy than a lead-acid battery will. They are also more durable and don’t lose their efficiency as quickly.

Keep in mind that this is also going to contribute to the cost of solar batteries. Higher-quality batteries tend to cost more. And the less efficient your batteries are, the more batteries you may need.

Size of Your System

The next thing you need to consider is the size of your system. How big is your house? How much energy does it take to power it?

This along with the type of batteries you want will be the largest contributors to your battery system. If your solar panels are creating a lot of energy that isn’t being used, then it only makes sense to try to store as much of that energy as possible.

One of the main reasons people get a solar energy system is for power independence. They don’t want to rely on an electric company to power their homes anymore. Having a solar battery for your home helps homes be less reliant on a power grid. 

But this is only helpful if the battery can keep your lights on even when your solar panels aren’t absorbing sunlight. In some cases, this means having more than one solar battery in your system. 

Having multiple solar batteries means that you have more energy stored to power your house at night or during emergencies. Therefore, you don’t need to rely on fossil fuels from your electric company to power your home as often. How long that lasts is going to depend on how much usable storage you have.

Usable Storage

This refers to the amount of energy stored in your batteries that you can actually use. 

When your solar panels are producing unused energy, they will charge your battery instead. That battery can only hold so much energy in it at one time. This is its storage capacity. 

But the amount of usable energy that a battery can produce is not equal to the energy that it can store. Most of the time, you can usually only use between thirty and eighty percent of a battery’s total storage capacity before it stops producing energy. This makes up the battery’s usable storage capacity.

How fast this goes is of course going to depend on how much energy you typically use. Temperature and age will also affect this value, and remember that batteries will slowly lose their charge even when they’re just sitting on a shelf. 

Ask yourself how much power you use in the evening hours. How often do you get heavy storms that take out the power grid in your area? 

Then ask yourself how much power independence you want. This will help you decide how much usable battery storage you want.

Power Rating

The power rating of a battery refers to how much power the battery can provide at one time. A normal AAA battery can’t power an electric oven for example. You need something bigger that holds more energy for that.

For solar batteries, this energy is measured in kilowatts. This will mostly serve to determine which appliances you’ll be able to use while on battery power. 

For example, it might be useful to keep your fridge running during a power outage, but your dryer may not be as urgent. Most people will want to keep their stoves, microwaves, and air conditioning running as well. 

So when choosing a battery system, think about which appliances are the most important to you. How much food will spoil if your fridge isn’t working? Do you have a way to cook if the power goes out?

This will help you narrow down your battery options since you will need to find the right batteries for your needs at that point. Then it all comes down to how efficient and reliable they are. This is a good way to maintain power independence, even during emergencies where the whole grid goes down.

Roundtrip Efficiency

While usable storage refers to how much of a battery’s stored energy can actually be used, roundtrip efficiency refers to how much energy you actually draw compared to how much energy it took to store it. In other words, the better the battery, the less energy gets wasted during the storage process.

If you want a better value for your system, then you want a battery with a higher roundtrip efficiency. They’ll take less effort to store and use energy than batteries with a lower roundtrip efficiency. This often also means that more of your stored energy is also usable.

There will always be some energy loss during storage because solar panels need to spend energy to create energy. The point is that they create much more than they use during the process. Solar batteries follow this same principle, which is why roundtrip efficiency may never be one hundred percent.

Fortunately, right now solar batteries all have fairly high roundtrip efficiency. Most of them are going to range between seventy and ninety percent. This is good news if you’re looking for a good value on your solar energy system.

You’ll get a better value for your money from batteries with higher roundtrip efficiency.

Battery Duration

The whole point of solar batteries is to keep your power on when your solar panels can’t generate energy. Even if you have a reliable solar energy system, there will be times where you have to rely on backup power. This is exactly why you want a battery system as well as solar panels.

Whether it’s at night, a power outage, or both you need to be able to rely on the battery for backup power. So the factor that’s probably the most important to you and your family is how long the battery will last during these times.

This is going to depend on the combination of the battery’s capacity and its discharge rate. In this case, discharge rate refers to how much energy your house needs to power it or the circuit power. Both of these can be given in amps by looking at the battery’s label and your home’s electric panel. 

All you need to do is divide the battery’s storage capacity by the discharge rate to get an estimate of how long the battery will last in hours. This is how long you have to make sure you’ve completed all tasks that require electricity before your power will go out.

Depth of Discharge

While doing that simple calculation can give you an idea of how long your battery will last, in practice things may work a little differently. For example, how much energy is your home using at one time? Chances are you’re using much less electricity when everyone in your household is asleep than when you’re cooking dinner.

This is called the depth of discharge. It is the energy that you draw from the battery relative to its capacity. As with all batteries, the more it is used, the faster it drains.

This determines how hard your battery has to work to power your home and then recharge afterward.

After some time, this will also put stress on your solar battery. This stress will slowly reduce the battery’s efficiency and capacity. This will continue until eventually, the battery can no longer support the amount of power your home needs.

In other words, putting a lot of stress on your battery all at once will effectively reduce the lifespan of your solar battery. Try to reduce your energy usage when your battery takes over providing energy to your home to reduce this effect. This will help your battery last longer and maintain the value of your system.

Battery Lifetime

A battery’s lifetime is going to refer to how long the battery can supply enough energy to your house to power it. This will slowly reduce on its own as the battery is used due to wear and tear. Using it to its full capacity often will also speed up this process. 

This will be determined by how many cycles a battery can perform before it dies. Lead batteries tend to be superior to lithium in this category. Lead can typically give a battery between three hundred to seven hundred cycles while most lithium batteries can only provide up to two hundred.

You want your battery to last as long as possible during an emergency. But you also don’t want to need to replace your battery frequently. That’s why it’s so important to take care of your batteries once they’re installed.

If maintained properly, a lead-acid solar battery can last as long as fifteen years. Meanwhile, a lithium-ion battery will last approximately ten years by comparison. 

But not every battery will last that long. So pay attention to warranties when selecting a battery for your solar energy system. This will tell you exactly what you can expect from your solar batteries.

Get a Solar Energy System for Your Home Today

Whether you want to help protect the environment or save some money, getting batteries for solar panels is a good idea whenever you get a solar energy system. It’s the best way to make sure your lights stay on even if the sun isn’t shining.

And when you’re ready to install solar panels and batteries at your house, then West Bay Energy is here to help. We’re family-owned and operated and have some of the best warranties in the industry. 

Contact us and let us help you switch to solar energy today.