Can I add more solar panels to my existing system?

Published: 8 May 2019

So you’ve invested in solar power and you’re enjoying the benefits, but you’re starting to wonder if it’s possible to expand your system and increase your savings. Is it as simple as adding more solar panels?

You have already experienced the advantages of solar, you are happy with your investment and have seen how your energy bills have been going down, thanks to solar energy. However, you may be wondering, can I have even more power? Do I need to consider adding more solar panels?

This is something that usually happens to solar customers after some time. First, they are not quite sure of making the investment in solar; they are not sure about how the technology works; whether the system they installed will be profitable; if the solar installer is reliable; if the products they purchased were good or bad quality, or maybe simply they didn’t have the money to install a big system. Therefore, many homeowners decide to install a small PV system at first, just to put solar energy to the test.

Nevertheless, as some years pass by, the homeowner realises that the investment made was indeed profitable, that it’s saving money on electricity and that they should have installed a bigger system. 

If that’s your case, here we will show the available options that you have to expand your PV system. But first, let’s take a look at an important question.

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What type of system do you have?

This is the first question that you must ask yourself. 

The difficulty and choices in expanding your PV system vary a lot depending on the type of system you have.

Grid-tied systems are the easiest PV topologies to expand, mainly because they do not have energy storage. 

Within the grid-tied market, there are two main types of systems; those with central inverters and those with microinverters

Systems with central inverters are composed of modules, inverters, combiner box, wires and other electrical components.

Expanding systems with microinverters is very easy because each module is independent of the other one. All that is needed is to add the number of panels with their corresponding microinverter and it will not affect any other component of the PV system.

The other types of systems include energy storage in the design. These can be as complex as it gets; installations with a DC-coupled solution, AC-coupled solution or installed with hybrid inverters. 

Expanding a PV system with these characteristics may not be that easy or cheap.

How do I expand my PV system?

There are several ways to expand your PV system.

1. Push your inverter to the limit

Solar designers use a parameter called DC/AC ratio to design a PV system. 

This parameter refers to the relation between the installed DC power capacity on modules and the installed AC nominal power output of the inverter. 

Since inverters are designed with specific power output sizes, they cannot comply equally for all PV systems. 

In some occasions according to your requirements, the solar installer will design your PV system to be approximately equal to the inverter, a little above or a little below the power capacity of the inverter. 

Since the power output of the PV system changes according to the solar radiation and the day, it is highly probable that the maximum peak power of the array will only be reached over 1 hour per day. 

Therefore, if the maximum power output of the sized array is 2.2 kW and the available sizes in inverters are 2kW and 2.5 kW, it is probable that your solar designer will opt to install the 2 kW option. 

Why? Because the 2.5 kW will cost much more and your PV system won’t reach those power capacities ever.

Actually, some inverters are able to increase their output capacity over short periods of time, therefore paying more for an amount of power that won’t make much difference would be unjustified.

This is called clipping losses, which refers to the limitations of the inverters in power output. 

The solar installer will probably size your PV system with a DC/AC ratio between 1 or 1.2. 

However, it is probable that you will be able to size your system up to 1.3 without losing too much power. If you want to expand your system, it is a good idea to check if you can extract more juice from your inverter first.

This is probably the first idea that should come to mind because you will be able to keep your inverter and avoid the expenses of other equipment – and you will still be able to access your solar rebate because you haven’t changed your inverter.

Expanding your PV system and understanding your DC/AC ratio

2. Install another PV system

The next valuable option is to install an entirely new PV system. 

The advantage of this option is that you can do it with another solar installer. 

In the previous option, if you expand the system with another solar installer, you will probably void the warranty. 

Moreover, this option allows you to install a completely different system that can be updated with new technologies, new and more efficient modules and other inverters. 

In this case, it’s probably better that you opt to install a microinverter system because they are more suitable for expanding arrays in the future.

3. Change your inverter

This is probably the last option that you want to consider. 

This is mainly because it will be necessary to dispose of your previous inverter in order to install a new, bigger and more expensive one radically increasing the overall costs of your PV system over time. 

Moreover, by changing your inverter, you won’t be able to access solar rebates.


As you can see, there are three available options to expand your PV system. 

If there is energy storage in the middle, it is advisable to install a new PV system separate from the older one. Mixing solar batteries with different capacities or aging times is probably not a good idea in most cases.

If you haven’t installed any PV system yet at home and are unsure about whether or not to install more solar panels, it is probably best to choose a microinverter system. That way, if you change your mind in the future, you won’t have much trouble expanding your system.

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Next Steps…

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Otherwise, you can always contact us on 1300 133 556, or email if you prefer at [email protected].

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