Solar batteries can be part of a home solar power system. With battery storage, it’s possible to save money and use more of the clean energy rooftop solar panels generate.
What are the basics of solar batteries? How do they work? How do they work with solar power? We’ll answer those questions in this guide to solar batteries.
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What Is a Solar Battery?
A solar battery is a device that stores any extra electricity your solar panels create. When your home needs more electricity than your solar panels can provide, your home can use the electricity stored in the solar battery for power.
In simplified terms, solar panels can send electricity into the battery or a bank of batteries, and your home can use electricity from the battery.
Unlike the batteries in your electronic devices, solar batteries are designed to be used for a long time. They can also be recharged regularly, so if you use all the electricity inside the battery, you can refill it over and over again.
How Does a Solar Battery Work?
A solar battery gives power just like any other battery. Imagine two buckets: one is filled with water, and the other is empty. If you connect those two buckets together with a hose, the water will leave the full bucket and start to fill up the empty bucket. Eventually, there will be a similar amount of water in both buckets, and the water will stop moving between them.
If you put a water wheel in the hose, you could use the flow of water between the buckets to turn the wheel, which generates power. And if you wanted to recharge your water-bucket system, you could use a pump to move water back into one bucket, and the whole system is ready to flow through the hose again and create more power.
With a battery, there are chemicals instead of buckets, and electrons instead of water. Electrons are extremely tiny things that can carry an electrical charge.
On the negative side of the battery, the chemicals have a lot of electrons, so the bucket is “full”. We call this potential energy or energy that’s ready to be used. On the positive side of the battery, the chemicals don’t have many electrons, so the bucket is “empty”.
When you connect the two sides together with a wire, the electrons flow from the negative side to the positive side. If you add a device in the middle of that connection, the flow of electrons can power that device as they pass through it.
With a solar battery, the solar panels on the roof of your home generate electricity from sunlight, which basically means they create a flow of electrons. (For a more detailed explanation, check out Explain Like I’m 5: Solar Panels.)
Those electrons can either flow through your house to power it, or that flow of electrons can get sent to your battery storage system to recharge it, adding electrons to the negative side. You can use the stored energy in your battery to power your home, for instance, when the sun isn’t shining or there’s a power outage.
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The Differences in Solar Batteries and Regular Batteries
The main difference is solar batteries are much bigger than regular batteries. Your home needs a lot of energy to power things like your TV or refrigerator, so the “bucket” in the home battery needs to be really big.
Unlike some batteries that are designed to be used only once, solar batteries are designed to be recharged many times. You can use them for a long time without losing too much of the ability to charge. Solar batteries work like other high-tech rechargeable batteries, including the lithium-ion batteries in an electric vehicle or an advanced device like a smartphone.
Lastly, another significant difference is what happens after the electrons leave the battery. When your home uses power, the electrons need to move back and forth, instead of just one direction. To do this, a solar battery gets paired up with a device called an inverter, that can change the flow of current from one direction, called direct current or DC, to a current that can change directions back and forth, called alternating current or AC.
DC Coupled vs. AC Coupled
There are two different types of home solar batteries: direct current-coupled and alternating current-coupled. In this case, coupled just means the type of electricity the battery receives.
Batteries can only store DC energy, so they may need to change AC electricity to DC before it can be stored. Once it’s stored, something has to change the energy in the battery from DC to AC electricity before it can be used for power.
- DC-coupled batteries - Store DC electricity directly from your solar panels, and then send it through a solar inverter so it can be changed into AC electricity that can power your home.
- AC-coupled batteries - Store electricity that’s already been changed into AC, so they use a special internal battery inverter to convert the electricity from AC back into DC for storage, and then send it through an inverter so it can be changed into AC electricity that can power your home.
DC-coupled batteries are often the best option if you’re installing a brand-new solar panel system because they store electricity more effectively without the need to change it from AC back into DC. AC-coupled batteries are often the best option if you’re adding a new battery to an existing solar power system because it’s a simpler system, so it’s usually cheaper to add on.
Reasons to Get a Solar Battery
There are many reasons you might want a solar battery with your home solar panels:
- You can send extra solar power your home can’t use to your battery, so you can use more of the electricity your solar energy system creates.
- You could have lower energy bills because your home can use the extra energy stored in your battery instead of using grid power, especially during the peak hours of time-of-use rates.
- You have backup energy available to power your home in case of power outages.
- A solar battery can help the environment because your home can use more solar energy and less fossil fuel energy.
If you’re interested in installing a solar energy system, talk to Palmetto today. Get started with our solar savings calculator or contact us, and one of our experienced solar technicians can walk you through all of your options.
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Cory O'BrienSenior Director - Growth MarketingCory brings over 8 years of solar expertise to Palmetto, and enjoys sharing that knowledge with others looking to improve their carbon footprint. A dog lover residing in Asheville, NC with his wife, Cory graduated from UCSB. If you run into him, ask him about the company he founded to rate and review beer!
