Understanding Solar Batteries: Why Are They Important for Solar Users

It’s not easy going solar.

While solar installations are a viable alternative, they may also be an intermittent source of electricity. What do you do to harness the benefits of solar power when the sun goes down, or it’s a particularly cloudy day? Then there’s the ever-changing Time of Use (TOU) rates that residential solar users under net metering tariffs need to consider.

These shortcomings of PV modules may dissuade you from going solar.

So, why do you need battery for solar panel? Read on to find out.

What Are Solar Batteries?

Solar storage batteries, as the phrase implies, are storage units that reserve the excess power produced by a PV module for use at a later date or time. The stored power can be utilized when your solar panel cannot produce enough electricity to meet your household needs.

If you’re under your local net metering tariff, batteries for solar can prevent excess power from flowing back to the grid. For on-the-grid residential solar users, solar batteries allow for significant savings on utility bills.

To add to that, they can be handy during emergencies. What if there’s a sudden power outage? You can depend on your solar storage device to power you through a blackout.

What Are Solar Batteries

Research reveals that households only utilize 35% of their PV module capacity at any given time. The remaining 65% can be stored for later use.

And if you’re wondering how long do solar batteries last, most batteries for solar systems last anywhere between 5-15 years.

A solar battery can help you make significant efficiency gains from your solar PV system installation and thus help reduce your overall carbon footprint.

So whether you’re an existing solar user or planning to go solar, consider investing in a solar battery.

Types of Solar Batteries

How well your solar battery will perform depends on several factors, the main one being its type. There are a few different types of batteries for solar panels available in the market, including:

Lithium-Ion Batteries

More commonly known as Li-ion batteries, these are the newest yet the most common type of battery that solar manufacturers offer.

There’s a good reason for that too.

Li-ion batteries are low maintenance and have an average Depth of Discharge (DoD) of around 95%. This means you can use more of the stored energy before it needs charging. Because of high DoD, most Li-ion batteries have a lifespan of 10 years!

However, most solar panels last for 25 years. Therefore, you will need to invest in two or more Li-ion batteries throughout the life of your panels to keep your solar solutions working efficiently.

These batteries work using a chemical reaction prompted by a lithium-salt electrolyte solution, much like the ones used in today's cell phones. In addition, Li-ion batteries are the “cleanest” of all solar batteries. Minimal raw materials go into their making, and most manufacturers make conscious efforts to reduce their environmental impact.

The advantages of Li-ion batteries far outweigh the disadvantages. In many ways, they are the best batteries for solar power storage currently available in the market.

The only con is its price. So, consider your budget before initiating the process of installing solar panels with Li-ion batteries.

Li-ion Batteries

Lead Acid Batteries

While they are the most affordable solar batteries on the block, lead acid batteries also have poor DoD at only 50%. Unlike Li-ion batteries, they are not energy-dense either. So these batteries cannot store a lot of power.

Although lead-acid batteries are quite reliable, they only have a lifespan of about 3-5 years. Even if your lead acid battery lasts five years, you’ll still end up buying five or more to support the lifespan of your current solar system installation. And when you add up the cost of solar batteries, the affordability factor of lead acid batteries doesn’t make sense.

Flow Batteries

Currently an emerging technology, flow batteries use the electrolyte flow between two chambers to store power.

Though bulky and expensive, flow batteries can store more solar power than their counterparts. Since the technology is still very new, you can expect upgrades and improvements to suit residential needs.

Nickel-Cadmium Batteries

This is another type of solar battery primarily used in commercial and industrial applications. Nickel-Cadmium batteries are durable and work flawlessly even at very high temperatures. They’re fairly low maintenance too.

But the biggest concern about using nickel-cadmium batteries is their toxicity.

How Does a Solar Battery Work?

So, how do solar panels work with batteries? Solar batteries are connected to the solar panels via DC (direct current) or AC (alternating current) coupling.

How Do Batteries Store Energy?

DC Coupling

In a DC-coupled setup, the direct current produced by the PV module is stored unchanged in the solar battery. It gets converted to AC only when the current enters the inverter that powers your household.

Because the current is converted from DC to AC only once, DC-coupled solar batteries are highly efficient. But they require complex installation that can only be done by trained professionals.

On the whole, DC-coupling a solar battery is efficient, although expensive.

How Does a Solar Battery Work

AC Coupling

If your solar battery is AC-coupled, the current produced by the PV module will first enter an inverter to be converted into usable alternating current. Any excess current will flow back to the inverter to be converted into direct current for storage.

So, the cycle is longer, with multiple instances of current conversions.

Therefore, in AC-coupled solar batteries, there’s always some loss. But AC-coupled batteries can store some power from your grid alongside the PV module. So these losses do not significantly impact how much electricity you have to power your house.

Choosing A Battery for Your Solar Panel

How to choose battery for solar panel depends on several factors:

Purpose of Use

Before choosing a solar battery: ask yourself why you need one.

Li-ion batteries are a great choice if you would like to store enough energy to power your home during the night or bad weather. They’re compact with the highest DoD, are low maintenance, and are long-lasting.

Because most solar manufacturers produce li-ion batteries, it’s easy to get these installed by professionals.

Choosing A Battery for Your Solar Panel


Another major consideration of what battery to use with solar panel should be the investment required to go solar.

Lead acid batteries are the most affordable and can be a good option if you’ve just invested heavily in your solar panel installation. They do the job, and you can always upgrade later.

Storage Space and Maintenance

Solar setups are space sensitive, and batteries are no exception. They also require regular maintenance to be at their optimal best.

If saving space is your priority, Li-ion batteries are a better option than others. Flow batteries are a good choice if you do not have space constraints and need a battery that can store a lot of solar power.

Lead acid batteries, although durable, take up a lot of space. However, they are easy to maintain. For those who want hassle-free solar usage at low costs, go the lead acid way.

The best type of battery for solar modules will depend on your immediate needs. Make a decision that caters to your unique requirements instead of going by the book.

Reach out to AMECO, a solar panel company for more information.