Adding BatteriesAllBatteries

Can I Add a Battery to an Existing Solar Energy System?

Posted on 11 October 2021

Recently energy retailers have started reducing financial incentives for households feeding excess solar power back into the grid. This change has led many more people to install solar batteries to increase their energy independence from the grid.

In 2021, an average solar system often produces more electricity than a home needs. This excess power is excellent during the daytime when a house can enjoy all that free electricity, but what about at night when there’s no solar power?

Because of this, many homeowners are installing solar batteries to store their extra solar energy, making it available for use when the sun goes down.

When the sun is shining, your panels collect energy and produce DC electricity. This DC electricity flows to an inverter, which converts the power into AC electricity, usable by power appliances, such as lights and devices in your home.

But what happens when your system generates more solar energy than you could use at that moment? Typically, excess power is wasted or exported to the grid for solar credits.

6 LG HV batteries configured to run three phase and off grid
One of our larger installations of LG HV batteries configured to run three phase and off grid

These solar credits are known as the solar feed-in tariffs (FITs). Currently, FITs are reducing yearly in Australia, prompting more people to save their excess energy in a battery instead.

Rather than exporting your extra solar energy to the grid for minimal credit, you can store your excess solar power in a solar battery, making it available for use at night. 

Others are looking for options to take their homes ‘off the grid’ or protect themselves from blackouts.

Adding solar batteries to an existing solar system provides an attractive incentive for homeowners looking to reduce their monthly bills even further or become completely self-sufficient.

Is it possible to add a battery to an existing solar system? Even an old solar system, or one that is not ‘battery ready’, how is this done?

Storage Ready Systems

The good news is, all solar systems can have solar batteries attached to them, in one way or another! The ‘type’ of solar system you have will affect the way you add a battery. If your solar system is battery ready, this means you have a hybrid solar inverter, which can have a battery connected directly.

Suppose you have a regular solar inverter that is not a hybrid. In that case, you will need to consider adding a battery with its own inverter that can also ‘interface’ with your existing solar system and use power from your current solar system to charge and discharge, even without being directly connected to that system.

As a side note, hybrid inverters are usually a ‘DC coupled’ configuration, and stand-alone battery inverters are generally an ‘AC coupled’ design.

What’s the difference between AC and DC solar batteries?

DC Coupling a Solar Battery

As mentioned above, a DC battery configuration is where a solar battery takes DC electricity directly from the solar panels. DC coupling is a slightly (about 5%) more efficient way to install a solar battery and usually takes place by using a ‘hybrid’ inverter.

The inverter is considered a hybrid when it combines a solar and a battery inverter into one unit. This combo unit allows the solar battery to take DC energy directly from the solar panels; the hybrid inverter can then convert this stored energy to usable AC power when the home requires it.

AC Coupling a Solar Battery

An AC battery configuration is advantageous when your existing solar system is not a hybrid system and therefore does not have any way to plug a battery in.

An AC coupled battery gets its name because it doesn’t take electricity directly from your solar panels, which produce DC power. Instead, it uses your extra solar power from the switchboard (which is AC power).

LG 10kW Solar battery
A 10kW LG Solar battery

In other words, an AC solar battery ‘watches’ your home’s switchboard, and it can ‘see’ when there’s extra solar power spilling back into the grid or going to waste.

When the inverter sees this extra power (via special meters in the switchboard, known as CT meters), it redirects the excess power into the solar battery.

An AC coupled battery can also ‘see’ when your home is about to pull energy from the grid and instead supply the property with enough power from the battery. This configuration means your AC solar battery will work with any solar system; because it works by reading electricity excess and deficits at the switchboard and redirecting battery power accordingly.

It usually does not matter what kind of solar system you already have connected to your property when adding a solar battery. You can always AC couple a battery.

An example of batteries that can be AC coupled are Tesla, SkyBox and LG solar batteries; however, LG and SkyBox batteries can also be DC coupled. Check out information about our custom SkyBox solution here.

Off-Grid and Blackout Protection

While we’ve covered how to add a battery to save money, it’s worth mentioning many people also want solar batteries for the benefit of being able to disconnect and go off-grid or to protect themselves from blackouts.

You can also DC or AC couple an off-grid battery (like the SkyBox). Meaning, if you already have solar and want to disconnect the grid, adding something like a SkyBox can allow you to go off-grid or gain blackout protection without having to alter your existing solar system at all.

Solar battery and inverters installed in a garage
A Solar battery installation with inverters

Your Bottom Line

Solar batteries are about saving money; others want to go off-grid and remain free from power companies. Whatever your reason, it’s great to know that you can add a solar battery to almost any existing solar system.

As a final note, if your current solar system is tiny, it may not be powerful enough to charge your new battery, so make sure you assess this in advance and consider adding more solar panels to help charge your battery even faster. 

Contact us for more information and specifics about your current solar energy system. We’re happy to help you go over the specifics involved in changes to your system and be sure View more about our custom SkyBox solutions.


2 responses to “Can I Add a Battery to an Existing Solar Energy System?”

  1. Phillip Dou says:

    I already have 51.2V 200Ah battery pack and solar inverter charger BSL4850U80-H, so I currently use 12 Tesla solar panels and Tesla inverters, I can combine two inverters of different systems Is it connected?

    • sidedish says:

      Hi Phillip, no we would have to be a standalone system – it doesn’t really interface with an existing battery system. Let me know if you have any other questions!

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