Is Your Commercial Building Ready for Solar? Here’s What Experienced Installers Check First

Electricity costs are squeezing margins for businesses across Perth and Western Australia, and more organisations are turning to commercial solar to bring some predictability back into their operating expenses.

Most start the same way: comparing panel brands and collecting three quotes.

That’s the wrong first step, and in Western Australia it’s wrong for a reason that doesn’t apply anywhere else in the country.

Why Western Australia Changes the Maths

WA sits on the South West Interconnected System, separate from the National Electricity Market that covers the eastern states. That isolation has a direct consequence for any business considering solar.

The Distributed Energy Buyback Scheme, WA’s export payment scheme, is open to households, schools, educational institutions and not-for-profit organisations. A standard for-profit business generally is not eligible. Even where export is credited, the off-peak buyback rate sits at around 2 cents per kilowatt-hour, while commercial grid electricity from Synergy runs somewhere in the range of 24 to 34 cents per kilowatt-hour.

The implication is blunt. A kilowatt-hour your business uses on site is worth more than ten times a kilowatt-hour you send back to the grid. In WA, exported solar is close to worthless to a commercial operation.

This is why a commercial solar assessment is not a formality. The return on a commercial solar system is decided almost entirely by how much of the generation your business actually consumes, and that can only be established by looking at how you use electricity, hour by hour, before anyone designs a system.

A business operating through daylight hours, such as manufacturing, cold storage, retail or hospitality, will typically self-consume a large majority of what it generates. A site with heavy overnight load will self-consume far less, and the same system will deliver a very different payback. Same roof, same panels, different outcome.

Understanding Your Energy Usage Profile

Because self-consumption drives the economics, energy profiling is the single most important part of the assessment.

Two warehouses of identical size can have entirely different requirements. What matters is the shape of the load, not the size of the building.

A proper assessment looks at:

• Operating hours, including weekends and shift patterns
• Interval data from your electricity account, ideally 12 months of it
• Seasonal peaks, which in Perth usually means summer cooling load
• High-draw equipment and when it runs
• Demand charges, which are often a larger cost lever than consumption
• Whether storage would shift surplus generation into your evening load

Twelve months of interval data is the difference between a system sized for your business and a system sized for your roof. Our guide to commercial solar ROI in WA covers how load profile analysis feeds into payback modelling. If an installer proposes a system without asking for that data, it is worth questioning.

Network Approval: The Timeline Nobody Budgets For

This is the constraint that most often derails a project schedule, and it rarely appears in a quote.

Commercial systems above 30 kVA sit outside the streamlined residential pathway and go through Western Power’s commercial application process, which is tiered. A flat enquiry fee of $250 plus GST applies, after which the application is classified as Basic, Reduced or Full. Basic carries no further fee, Reduced costs $2,500 plus GST, and Full costs $5,000 plus GST for systems up to 200 kVA.

The timeframes matter more than the fees. Western Power aims to approve a Basic application within 45 days, a Reduced application within three months, and a Full application within twelve months.

A business that signs a contract in July expecting generation by spring can find itself waiting considerably longer, depending on which pathway the system falls into. An experienced installer will indicate the likely classification during the assessment, before you commit, rather than after.

Note also that Western Power covers Perth and the south-west. Regional sites fall under Horizon Power, which operates its own networks and connection arrangements, and in some locations export may be restricted entirely. For remote sites, an off-grid or hybrid system is sometimes the more practical route.

Inverter rules in WA were also updated from 1 May 2026, with aggregate inverter capacity now assessed as a combined total and revised export control requirements. Any design produced against the previous rules needs rechecking.

Evaluating Your Existing Electrical Infrastructure

A commercial system has to integrate safely with what is already in the building. This does not automatically mean expensive upgrades, but it does need to be established before design, not discovered during installation.

An assessment typically reviews:

• Main switchboard condition and available capacity
• Existing protection devices and their adequacy for a generation source
• Compliance with current Australian standards, including AS/NZS 5033 and AS/NZS 4777.2
• Suitable connection points for the proposed system
• Metering arrangements, which may need to change

Assessing Your Roof and Building Layout

Roof space is the constraint most people focus on and rarely the binding one.

Installers assess:

• Orientation, noting that in WA a west-facing bias can better match afternoon load and peak demand periods
• Roof condition and remaining service life, since re-roofing under an installed array is expensive
• Sheeting type and structural capacity
• Shading from adjacent buildings, plant and rooftop equipment
• Access for installation and ongoing maintenance
• Cable pathways between array and switchboard

Roof age deserves particular attention. If the sheeting has under ten years left, it is usually cheaper to replace it before the array goes on than to remove and reinstall panels later.

Planning for Business Growth

Designing purely around today’s consumption is a common and expensive mistake, particularly given the approval timelines above. Going back through the process to expand a system is not a small undertaking.

Worth discussing before design:

• Planned expansion of premises or production capacity
• Additional plant that will increase daytime load
• Electric vehicle charging, which adds daytime demand and improves self-consumption
• Battery storage as a later addition, which affects inverter selection now
• Changes to operating hours or shift patterns