Skip to content

How much does it cost to add more solar panels in Perth?

There’s no hiding; adding more solar panels can be challenging for modern solar energy systems. Accountable for 90% of solar energy systems in Perth, WA, solar panels within a string inverter system must be matched for similar electrical characteristics, assisting uninhibited electrical flow throughout the solar array. Coupled with generational solar panel dimension and characteristic changes, adding more solar panels to your existing solar energy system can sometimes be more complex than first thought.


In a short period of research, you’ll identify that most solar installation companies want to avoid adding more solar panels to your existing solar energy system and will often default to recommending an entire system upgrade. Yet you have a perfectly functioning system that seems ridiculous to remove and discard based on your commitment to greener energy outcomes.

Indeed, there is a market for adding more solar panels to existing solar energy systems globally, but is it viable in Western Australia?

A defection among installers of adding more solar panels to your existing system exists in two forms:

1) The cost of adding more solar panels vs current market new system options due to available subsidies.

2) Electrical characteristics (mismatch) among newly available solar panels since you installed the original solar energy system.

3) Scarcity of previous-generation solar panels for ideal compatibility.

Within, we’ll explore what has changed since you installed your solar energy system and the current market prices of adding more solar panels vs removing and replacing with an entirely new solar energy system for the greater Perth, Western Australia region.

Size matters

Consider the output of your current solar panels. Standard previous-generation solar panel sizes on Perth homes are 250W, 275W, 330W, 370W, 390W, and 415W. Finding a similar-output solar panel is essential if adding it to a string [inverter] solar system. As the more affordable solution, these account for approximately 90% of solar installations in Western Australia.

Power output is one of many considerations systems designers need to make. Irrelevant to the brand, solar panels have vastly different electrical characteristics depending on their cell architecture (60 cells, 72 cells, 120 half-cells, 144 half-cells, shingled, etc.). The internal solar cell foundation (poly or mono) and configuration (architecture) are important aspects affecting two essential string inverter design elements, Isc and Voc.

  • Isc: Short Circuit Current
  • Voc: Open Circuit Voltage

These two figures are essential to a string’s solar panel compatibility. The closer the better for optimal system performance when matching: Brand (if possible) and cell architecture.

In short: If similar solar panels can’t be sourced, adding more solar panels to your existing string-wired solar system could have minimal to negative benefits.

Past installation standards

Your previous solar energy system may have been installed according to prior electrical standards. When a technician alters the existing system, they must notify with an Electrical Safety Certificate that the alteration/addition meets current electrical standards. Their personal and company licencing ensures your property is insured, and the statement must be correct. It will be considered a significant alteration for notifiable work (an increase of power class), and the system it incorporates must meet the current standards.

In short: The cost of adding more solar panels becomes elevated when an existing system upgrade is required.


When adding more solar panels, there are different warranty layers of obligations to consider, as the last person who worked on the system will always choose to absolve themselves from warranty ownership of the existing system if it is within a particular warranty period. We’ll always encourage building your energy ecosystem alongside a proven local installer to ensure your original installation warranty remains uncompromised. It is recommended that you consult the prospect of adding more solar panels with your original installer first. 

Perth Solar Warehouse compliments future system upgrades and improved warranty assurance with 20 years of business operational history and one of the most proven local guarantees.

In short: Adding more solar panels to an existing system may affect the original installer’s warranty.

Discover hassle-free solar. We’re a proven local WA company measured x time. Google & SolarQuotes 4.9/5.

Subsidy qualification

Does the existing system qualify for the current solar rebate (if available) to aid the reduced cost of adding more solar panels? The Small Technology Certificate (STC) subsidy is determined by the ability of your sustainable energy system to offset carbon emissions effectively. If your existing solar energy system doesn’t meet the current Australian and local standards, the cost of adding more solar panels will become 100% reflective of the actual price.

Further complicating layers to subsidy qualification, the existing system’s inverter must be on the current approved CEC list of inverters. Past approvals don’t qualify. The new solar panels must also be on the current CEC list of approved solar panels.

Related: How much are you entitled to? Perth’s solar subsidy amounts ›

What does it cost to add more solar panels?

Should the existing system qualify for the current period Small Technology Certificates (subsidy), adding more solar panels can often be calculated at a cost-per-watt, better assisting with normalising residential solar energy system costs.

As a gauge, the cost to add more solar panels to an existing string-wired solar system in the greater Perth region of Western Australia ranges from $1 to $2 per/Watt.

Example: On the more economical end of the spectrum, a 440W solar panel upgrade will likely cost $440 after qualifiable subsidy discounts at the point of sale.

Always seek a site-specific quote for accuracy. We can assist.

As a guide, to remove and replace your existing system starts from $.50c per/Watt. 6.6 kW Solar ›

Sunwiz Awards 2024: Perth appreciates Perth Solar Warehouse’s customer-centricity, local public knowledge base and high-quality outcomes. Best solar company (Australia) by customer satisfaction data [2023,24]. 

Alternative options

Avoid the subsidy: It’s an option, but specific standards for energy generation supply equipment must still be adhered to. As a guide, the cost of adding solar panels with the subsidy applied often offsets the panel cost. The price is likely to be similar.

Remove the current system. Go new. It’s now the most popular method towards expanding a solar energy systems capacity in Perth, Western Australia. Starting from 50c per/Watt, what should be the seemingly more expensive option can often cost less while improving user-system experience, performance and function with more modern technology.

Solar Panel Guides

Ranked as one of the best solar companies in Perth by review

Ranked as one of the best solar companies in Perth by review

With enough time, the best solar companies Perth has to offer begin to surface. Over a decade of mainstream popularity
Read more
Synergy Kaya GAs fired power station with blue sky in the background image for Synergy Electricity Rates Perth WA

Synergy electricity rates Perth 2024: Continuous Increase inevitable

How much will Synergy electricity rates increase in 2024 and beyond? Irrelevant to whoever is in government, mitigating the effects
Read more
Sigenergy SIGENSTOR render with with five in one key features listed: Solar Inverter, EV DC Charger, Battery PCS, Battery Pack, EMS

Review: Sigenergy’s ‘SigenStor’ is a game-changer for Australia

Now and again, a product comes to Australia, captivating the attention of solar energy enthusiasts. With world-renowned leading brands that
Read more
Sunrise over Perth City for Solar Rebate Perth WA

Ultimate guide: Solar rebate Perth and Bunbury WA region 2024

Exercise caution surrounding subsidy hype. Even though the zone 3 solar rebate Perth and Bunbury region customers can access isn’t a
Read more
New Fronius Inverter (GEN24) on a concrete wall with a female technician checking the app

Is a Fronius inverter worth the additional cost?

Many say yes, and some say no. However, it’s 2024, and a decade of innovation has passed since the launch
Read more
Sunwiz Awards 2024 with Derek McKercher in the foreground standing infront of a room full of people with arms crossed and smiling. Sunwiz Awards logos featured in the top left corner

Sunwiz Awards 2024: Top 5 WA and a Best Rated Solar Company Australia

Each year, market intelligence firm Sunwiz compiles solar market data to identify trends better and assist in improved decision-making content
Read more

What's your cost? It's free to ask

Hassle-free workplace electric vehicle charging. Save up to 50%.

What's your cost? It's free to ask

Your quote for a hassle-free commercial solar system begins here.

What's your cost? It's free to ask

Your quote for hassle-free, affordable EV charger installations begins here.

Your interest-free solar price in a few questions.

Important: This form takes approximately 15 seconds to process thoroughly. Perth Solar Warehouse supplies turnkey products in Western Australia (Perth & Bunbury region).