What’s the Difference between AC and DC Coupled Battery Storage Systems - My Florida Solar East LLC

What’s the Difference between AC and DC Coupled Battery Storage Systems



The use of renewable energy in the United States and across the globe has begun to explode.

In fact, most recent estimates state that roughly 18% of all electricity produced in this country has come from renewables.

One of the biggest downsides to renewable energy is that you can only use it while it is being produced. This usually means while the sun is shining or while the wind is blowing. This problem is usually solved in states with a net metering policy, but not all states have this making this a difficult issue to solve.

Now, thanks to battery power systems solar and wind energy can be stored while it’s being produced and used later when it is called upon.

So, what are the questions that need to be addressed so that consumers can better understand battery and energy storage systems?

  • What Is The Benefit To A Battery Storage System?
  • What Is The Difference Between AC and DC Electricity?
  • What Is The Difference Between AC and DC Coupled Batteries?
  • In What Scenarios Would Each System Be More Beneficial?


What Is The Benefit To A Battery Storage System?

The biggest benefit to having batteries connected to any energy consuming building, whether this is residential or commercial, is both energy security and the ability to rely on renewable energy around the clock.

When the sun goes down or the wind stops blowing, most homes and businesses powered by renewables begin taking in energy from the grid. This grid electricity usually is a mix of all kinds of electricity generation ranging from clean renewable energy systems to much dirtier coal fired power plants.

By adding batteries into the mix, you can almost fully eliminate the need to ever pull power from the grid. Instead, when renewables cease to generate, power stored in these batteries from the renewable energy systems can be used in its place. In regards to energy security, battery banks act as a backup power source for your home or business. This way, if the grid ever goes down because of an accident or a major weather event, the home or business can almost seamlessly switch over to pulling power from the batteries while the local utility gets the grid back in order. As long as the system continues to operate in the optimal battery voltage range, you should have a reliable power source for hours.


What Is The Difference Between AC and DC Electricity?

The biggest difference between alternating current (AC) and direct current (DC) is the distance each one of them can travel without suffering major losses.

AC coupled battery

AC electricity is able to travel much further distances than DC electricity because it is a very controlled current that cycles at a very set rate. This allows engineers and electricians to know exactly how it will act.

DC coupled battery

DC electricity on the other hand is much more unpredictable and, if sent over long distances, will suffer major losses because its movements are much less predictable.

Alternating current is the type of electricity that is used to transmit power across the country while direct current is the type of electricity is used to charge a cell phone or a laptop battery. The block in a cell phone or laptop charger is what switches alternating current to electronic dc loads, acting as a small inverter. In solar systems, the solar modules produce direct current and then an inverter switches this to alternating current which all homes and businesses typically use.

The biggest difference between ac dc electricity is an important one that needs to be fully understood before applying it to battery systems.


What Is The Difference Between AC and DC Coupled Batteries?

Battery and energy storage systems can either be AC or DC coupled. The biggest difference between these two types of power systems are the types of inverters that are used.

AC coupled battery

An AC coupled system will typically use at least two inverters. The first will be a typical solar inverter which converts the power from DC to AC. The second is a DC portable power inverter which then switched this load back to DC so that the battery can be charged. Of the two, an AC coupled battery is much easier to both design and implement.

DC coupled battery

A DC coupled battery system on the other hand only requires a single inverter. This is because this inverter is used for both the battery and the solar array that it is paired with. Because this type of inverter is much more specialized, it may be slightly more expensive than a typical solar inverter.

A home or business owner may use their sole discretion for what type of coupled battery storage system to use.


In What Scenarios Would Each System Be More Beneficial?

While battery systems of both designs can be implemented most anywhere, there are a few deciding factors which may allow someone to lean more towards one option over the other.

AC coupled battery system

First, AC coupled battery systems are usually cheaper so if cost effectiveness is your biggest concern, then you may want to go with this option. Additionally, it is far easier to install an AC coupled battery system if you already have a solar array installed.

DC coupled battery system

Conversely, it may make more sense to install a DC power system if you are installing it, in addition to a solar array, all at once. This is because DC portable power systems are usually more efficient and suffer fewer power losses given that the electricity only has to go through a single inverter versus two inverters. So, if maximizing the output of your battery is the biggest concern, a DC power system may be the better option. There are even scenarios where electronic DC loads, such as a DC air conditioner, may be utilized to even further minimize losses.

TIP: It should be noted that in both cases an optimal battery voltage range must be used to ensure an extended lifespan of either system design.

The difference between ac dc coupled batteries is important for home and business owners who are seeking to implement renewable technologies into their respective buildings. Implementing power systems solar or otherwise can be highly difficult if people fail to do the proper research ahead of time. Luckily, if done correctly, these technologies will only enhance our current quality of life. As the popularity of renewable technologies grow, expect storage technologies to become more popular as well.

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