Solar batteries may be a smart upgrade for your existing solar energy installation. Here are some things to think about if you’re considering this option for your home.

How long do solar batteries last?

It depends.

Based on various technologies used in solar batteries right now, you can expect a solar battery to last anywhere from 5 to 15 years. Several things have an impact on how long your battery lasts.

Usage – The life expectancy of a solar battery is directly related to its usage cycles. Usage cycles are the number of times a battery goes through a full charge and discharge cycle. Most batteries are deep-cycle batteries, which means they can discharge up to 80% of their stored energy before they recharge. This is important to make sure a battery doesn’t overcharge, keeping it as healthy and efficient for as long as possible.

Temperature – The location of your battery is another critical factor in determining how long it lasts. If you live in a mild climate, you can install it outdoors. But if you live in an environment with harsh or extreme temperatures, your battery will take a beating, which reduces its life span. To maximize life expectancy and efficiency, consider installing a battery where it will enjoy optimal temperatures, such as in a basement or a garage.

Maintenance – If you don’t take care of your batteries and solar panels regularly, they won’t last as long.  Take into consideration any maintenance or warranties that are offered to avoid costly replacements or repairs before they are necessary.

Type – The type of battery you choose has a direct impact on how long it will last.  So, let’s take a closer look at the types of solar batteries that are available on the market and which one may be the best for you.

What Type of Solar Batteries are There and Which Is Best?

Lithium-ion –  This is the most common type of battery that is used in homes. You have heard about lithium-ion batteries before because they use technology that is similar to what smartphones and laptops use. There are several sub-types of lithium-ion batteries that power solar batteries. These include lithium nickel-manganese-cobalt (NMC)and lithium iron phosphate (LiFePO, or LFP). Different solar battery manufacturers use each of these chemistries.

Each of these can give several thousand charge/discharge cycles and also discharge slowly (up to 80-90% of capacity), giving them a long life. All are suitable for a wide range of ambient temperatures, easing concerns about install location. They are durable and should last for ten years or more on a standard installation.  LFP technology is considered safer than NMC because it has a lower risk of thermal runaway, which is battery damage that can cause fires due to overheating or overcharging.

On the downside, lithium-ion batteries contain several valuable and toxic metals, meaning that it is critical to recycle them at the end of their useful life.

Lead-acid or advanced lead-acid (lead-carbon) – This type of technology is well known as being used in car batteries. It’s older, reliable, and well-known technology, but as technology evolves and costs go down, lead-acid batteries may have a tough time competing in the marketplace. They have a slow recharge cycle, are sensitive to high ambient temperatures and are relatively bulky.  So they end up taking up valuable space, especially when a battery installation takes place indoors.

On the plus side, lead-acid batteries are relatively inexpensive.   And because of car battery recycling programs already in place, the ability to recycle lead-acid solar batteries is also already in place as well.

Flow – A relatively new technology, flow batteries use a pumped electrolyte and chemical reactions to store a charge and then release it. Flow technology batteries offer several advantages. They operate well in high ambient temperatures, don’t lose capacity over time, are easy to recycle, and they can be discharged 100%.

The downside is that these types of solar batteries are expensive and can require maintenance, which means they can be out of service more often than lithium-ion batteries.

Solar battery technology continues to advance and change, and there are other lesser-used types on the market. They are in various stages of development and may hold promise for the future, but right now they are not widely used. They include:

  • Aquion hybrid ion (salt water) batteries
  • Molten salt batteries
  • Supercapacitor batteries (mfg. by ArvioSirius)
  • NiCad (Nickel Cadmium)batteries
  • NiFe(Nickel Iron)batteries

How do solar batteries work?

Solar batteries store energy produced by the sun and solar panels. This allows the energy to be used at a later time when needed.

Solar panels can be wired directly to a solar-powered device, while others may use a solar battery back-up. There are a couple of different types of batteries that are employed, based on the energy is used.

Boat lighting, appliances, and RV lighting use a 12-volt DC system. Inverter systems operate household necessities such as refrigerators, TVs, stoves, and so forth. They can convert 12, 24, or 48-volt DC battery voltage into a 120-volt AC that powers these types of appliances.

Hybrid solar power systems use wind, generators, or solar panels that plug into a battery bank to provide for ongoing energy needs.

Solar battery banks are designed for a specific charge or discharge levels. This means when using a solar battery system, you must make sure to use the right specifications and number of batteries. For example, you would not use a golf cart battery for a home battery storage function. Using the wrong type or size of battery can be dangerous.

Almost all residential solar systems are connected to electric company grids (this is also known as grid-tied). When a residential system is producing more energy than it needs, the excess feeds back into the grid. When a system provides less than the residence needs, being grid-tied means that power can be drawn from the grid.

If you supply power to the grid, you will receive a credit on your electric bill instead of paying more to an electric utility. This is known as net metering. Electricity is only sent back to the grid when your battery is fully charged, and you only draw electricity from the grid when your battery is depleted.

How much do solar batteries cost?

Because technology and competition are moving quickly in the marketplace, the overall costs to add solar battery systems continues to drop.

Your actual costs will vary and not including installation (which needs to be done by a licensed electrician), and related equipment, may run in the range of $5,000 to $7,000. The type of battery you choose and the relative capacity will also impact your actual costs as well.  Also, make sure you budget for the building permit process since an electrical installation is involved.

Installing a battery that can operate off-grid typically also costs more than installing a battery designed to operate while connected to the grid.

Keep in mind that unless your battery comes with a built-in inverter, that will also need to be installed so you can manage the flow of electricity to and from a battery.

How many batteries do I need for my solar installation?

The number of batteries you need will depend on what your energy storage objectives are for your home.

Solar batteries come in different sizes, so you’ll have to make some decisions about capacity, power, specifications, and what the primary purpose of the battery will be.

Can you add batteries to your existing solar installation?

Absolutely!

If your solar installation was designed with adding a battery at a later time, then you likely already have a storage-ready system with an inverter. This means integrating a battery into your existing system should be a relatively easy task. But if your solar installation was not originally designed to add battery capacity, you can still do so with a bit more effort and cost.

When adding a backup battery to your existing solar panel system, you need to discuss the specifics of your system, your storage objectives, and current electricity use with your installer to figure out what the best option will be for your home.

Where can I buy solar batteries?

A quick search online will provide you will all the sources you need to buy solar batteries.  Like other large purchases, your best bet is to do your homework, work with an industry expert, compare prices and specifications with your anticipated needs, and then make a final decision.

Does the Solar Investment Tax Credit cover batteries?

When you install a solar system, and it includes solar batteries, the tax credit does cover them. But if you install batteries separate or at a later date from your original solar system installation, you will not be able to take advantage of this incentive.