Solar Batteries for Home: A Comprehensive Guide
Solar batteries store excess energy your solar panels produce to use at night, on cloudy days or during power outages. Adding them to your system allows you to use more of the solar energy you’re creating, reducing overall energy costs and maximizing your savings.
If you’ve been looking to install a solar panel system recently, you’ve probably come across the topic of solar batteries. Despite the fact that battery systems are becoming increasingly popular, many homeowners still don’t know a lot about them.
Solar batteries let you store the energy that your solar panels produce for later use. Pairing your solar panels with solar batteries to create what is known as a ‘hybrid solar system’ comes with a number of advantages, including access to reliable backup power and independence from your utility.
What to Look for When Choosing a Solar Battery
Solar batteries have contributed significantly to the growing use of solar energy. They store surplus power generated during the day for use when the sun goes down, or when it disappears behind the clouds. Also, with a battery you can use less electricity from the grid, resulting in a lower utility bill.
In fact, you may not even need a large battery to see the benefits of energy storage. Even a small battery can noticeably lower your time of use (TOU) rate, the variable rate that utility companies apply based on when demand is high or low throughout the day.
But not just any solar battery can do the job perfectly. Before you talk to a solar installer about PV systems and the accompanying solar batteries, you need to learn how to choose the most efficient solar battery. The following factors should help you select the right solar battery for your solar energy needs:
Battery capacity
The capacity of a battery is the amount of energy, measured in kilowatt-hours (kWh), a particular battery can store. In other words, Capacity will determine how much electricity your battery can store, and how long the charge can last. Before selecting your solar battery, you could start by establishing your daily energy consumption to determine your PV system size.
To determine your daily energy requirements. Consider the following:
Appliances you use regularly in your home
Length of time electricity is actively in use each day
The readings on your average utility bills
Power
Before choosing your preferred solar battery, look at its power in terms of its peak and continuous delivery performance. Power is an important factor since the battery capacity may not be enough in determining the best solar battery for your home. You will find high capacity and low capacity batteries and may wonder which ones to choose.
A high-capacity low-powered battery can supply power for a few essential appliances, such as the fridge, or washing machine, for a long time. A low capacity but high-powered battery may power your entire home, but for a limited period of time. Ask your solar installer how you can establish a balance between capacity and rating and they should help you choose the right solar battery for your needs.
Depth of Discharge (DoD)
The chemical nature of solar batteries requires some charge to keep them working efficiently and longer. Depth of Discharge (DoD) refers to the amount of charge you can use from your battery before you affect it’s optimal performance. A higher DoD means you can use more of your solar battery capacity before you need to recharge it.
For example, a 10 kWh solar battery with 80% DoD means you should never use more than 8 kWh of its stored power. Exceeding this limit may shorten its lifespan significantly.
Round-Trip efficiency
Round-trip efficiency represents the amount of energy put in the battery that can be retrieved for practical use. The higher the round-trip efficiency, the more efficient and economical the battery is.
To better understand the concept of the round-trip efficiency, consider this example: if your battery can hold up to 10kWh of power, but you can only use 8kWh of it, your battery has a round-trip efficiency of 80%. If you are shopping for the best solar battery, get one with the highest round-trip efficiency.
Warranty
Manufacturers offer a wide range of warranties, depending on the brand as well as the type of battery. Lead-acid batteries usually have a shorter warranty period compared to more expensive lithium-ion, which can be covered for up to 10 or more years.
Lifespan
The battery’s ability to store charge diminishes with use, and eventually, you will realize it does not hold as much power as it did when it was new. After years of use, depending on its quality, the battery may stop holding charge completely. In general, batteries with a longer break-in period before reaching their peak capacity performance tend to have a longer lifespan, compared to those with a high initial capacity.
Cost
The price of a solar battery is perhaps one of the most important factors to consider before making the purchase. You will have to strike a balance between affordability and quality when deciding which solar battery to buy. The cost of solar batteries ranges from $3,000 to well over $20,000.
How solar batteries work
Solar batteries store the extra solar energy your panels produce that you don't immediately use, so you can draw from it later.
See, solar panels produce the most electricity during the middle of the day, which also happens to be the time when your home uses the least amount of electricity. With a regular grid-tied solar system, that excess solar energy gets sent back to the utility grid.
When solar panels are paired with a home battery, however, that excess electricity goes into the battery instead of going to the grid. Then, when the sun goes down and your panels aren’t producing electricity anymore, you can use the energy you have stored in your battery - instead of paying for electricity from the utility.
This means you get to power your home with all of the clean, renewable solar power your solar panels produce no matter what time of day it is.
Are solar batteries worth the extra cost?
Although pairing solar panels with energy storage is becoming more common, it doesn’t mean it’s the right choice for everyone.
Installing a solar battery storage solution provides the greatest benefits to homeowners who live in areas that experience frequent power outages, where full-retail net metering isn’t offered, or if there are battery incentives available in their area.
Solar batteries are also great if your main reasons for going solar are environmental, as it maximizes the amount of renewable energy your home uses.
However, if you’re only looking to save extra money, a solar battery might not be worth it for you. What we mean is, if you live in a state with full-retail net metering, you’ll be saving the same amount of money with a battery as you would without one. All the battery would be doing is adding thousands of dollars to your solar installation and providing you peace of mind in the event of a power outage.
Types of Solar Batteries for the Home
It is also vital to know the types of solar batteries available. Here are the two most common types, and their pros and cons:
Lead-Acid
These batteries are the oldest on the market and the cheapest energy systems to use. They are the best bet if you need lots of energy but wish to go off-grid. They come in two types: flooded, which requires regular maintenance, and sealed, a maintenance-free option.
Pros:
The most affordable solar battery type available
Quite reliable
Suitable for off-grid power needs
Cons:
Lower DoD of about 50%
Shorter lifespan compared to other battery types
Much larger and occupy more space per kWh
Types of Solar Batteries for the Home
It is also vital to know the types of solar batteries available. Here are the two most common types, and their pros and cons:
Lead-Acid
These batteries are the oldest on the market and the cheapest energy systems to use. They are the best bet if you need lots of energy but wish to go off-grid. They come in two types: flooded, which requires regular maintenance, and sealed, a maintenance-free option.
Pros:
The most affordable solar battery type available
Quite reliable
Suitable for off-grid power needs
Cons:
Lower DoD of about 50%
Shorter lifespan compared to other battery types
Much larger and occupy more space per kWh
Solar panels and solar batteries make a great pair
Installing a solar battery storage system can be a great way to get the most value out of your solar panels.
Batteries are an excellent source of backup power, they increase your energy independence, and in some cases can even save you more money on your electric bill because you’ll be drawing power from the battery instead of the grid.
However, solar battery systems do come at a price. If you’re looking to save money on your electricity bill, installing a solar battery might not be right for you, especially if your utility offers net metering. However, if you live in an area that experiences widespread blackouts, like the ones in California and Texas, or somewhere with Time-of-Use (TOU) utility rates, having a battery backup to store energy for when you need it will be beneficial.
The upside is that the price of solar battery technology continues to fall, so much so that someday in the near future, solar batteries will come standard with all solar energy systems.
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