How to Choose the Right Commercial Solar System Size for Your Business

Choosing the right commercial solar system isn't simply about installing as many solar panels as your roof can fit.

For Queensland businesses, the right system size depends on how much electricity your business uses, when that electricity is consumed, available roof space, network requirements and how your operations may change in the future.

A properly sized commercial solar system can help reduce grid electricity costs, improve energy independence and deliver better long-term value. An incorrectly sized system may leave valuable roof space unused or generate significantly more electricity than your business can effectively use.

So, how do you determine the right commercial solar system size for your business?

Start With Your Business's Electricity Usage

Your electricity consumption is one of the most important factors when designing a commercial solar system.

Unlike many residential properties, businesses often consume a significant amount of electricity during daylight hours — exactly when solar panels are generating power.

Warehouses, manufacturing facilities, offices, workshops, retail centres and agricultural businesses can therefore be particularly well suited to commercial solar.

Before recommending a system size, your commercial solar installer should assess factors including:

• Total electricity consumption
• Daytime energy demand
• Operating hours
• Seasonal changes in electricity usage
• Peak demand
• Electricity tariffs
• Available roof or ground space
• Planned business expansion
• Future equipment or EV charging

Looking at the site's actual energy profile allows the system to be designed around the business rather than simply choosing a standard commercial solar package.

Is a Bigger Commercial Solar System Better?

Not necessarily.

A larger commercial solar system can generate more electricity, but the goal should be to make that electricity valuable to your business.

For many commercial sites, solar self-consumption is particularly important. This means using the electricity generated by your commercial solar panels directly within the business instead of exporting excess energy to the grid.

A business operating heavily between 7am and 5pm, for example, may be able to use a substantial amount of its solar generation as it is produced.

However, a site with lower daytime electricity consumption may require a different approach.

The right commercial solar system size should balance generation with your site's electricity demand, available space, export limits and long-term energy strategy.

100kW Commercial Solar vs Larger Systems

The 100kW commercial solar system has historically been an important threshold in Australia because of the way federal solar incentives operate.

But that doesn't mean 100kW is automatically the right system size for every commercial property.

A warehouse, manufacturing facility or other high-energy business may have enough daytime electricity demand to justify a 150kW, 300kW, 500kW or even larger commercial solar installation.

If the business has the electricity consumption and suitable space to support a larger system, limiting the design to 100kW may mean missing an opportunity to offset more grid electricity.

This is where detailed commercial solar system design becomes important.

Instead of asking “How much solar can we install?”, businesses should be asking:

“How much solar makes sense for the way our site uses electricity?”

Consider Your Available Roof Space

Electricity usage isn't the only factor determining commercial solar system size.

The property itself also needs to be assessed.

Large warehouses and industrial buildings can provide excellent opportunities for commercial rooftop solar because of their extensive roof areas. However, not every section of a roof will necessarily be suitable for solar panels.

A commercial solar assessment should consider:

• Roof orientation
• Roof condition
• Structural suitability
• Shading
• Existing rooftop equipment
• Ventilation systems
• Access requirements
• Available switchboard capacity
• Future building works

Solar panels also need to be positioned in a way that allows for safe installation, maintenance and ongoing access to other equipment.

That's why commercial solar system sizing should involve a site-specific design rather than simply calculating how many panels physically fit on the roof.

Don't Forget About Future Business Growth

A commercial solar system is a long-term investment, so designing only around today's electricity consumption can sometimes be short-sighted.

Consider what your business could look like over the coming years.

Are you planning to:

• Increase production?
• Add machinery or equipment?
• Expand operating hours?
• Electrify existing equipment?
• Install EV chargers?
• Add electric fleet vehicles?
• Expand the building?
• Introduce commercial battery storage?

All of these can change your future electricity requirements.

Allowing for future growth during the initial commercial solar design can help ensure your system continues to support the business as its energy needs change.

Should You Add Commercial Battery Storage?

Commercial battery storage isn't necessary for every solar project.

Businesses with strong daytime electricity consumption can often use a significant proportion of their solar generation directly, which can make commercial solar highly effective on its own.

However, commercial batteries may be worth considering when a business wants to:

• Store excess solar for later use
• Reduce evening grid consumption
• Manage peak electricity demand
• Improve energy resilience
• Provide backup power for selected operations
• Support EV charging
• Increase solar self-consumption

Whether commercial battery storage makes financial and operational sense depends on the site's load profile, tariff structure, solar generation and business requirements.

Solar and battery storage should therefore be designed as part of the broader energy strategy rather than simply adding a battery because one is available.

What Do the October 2026 STC Changes Mean for Larger Commercial Solar Systems?

There is another reason commercial solar system sizing is particularly relevant in 2026.

The Federal Government has announced plans to expand eligibility under the Small-scale Renewable Energy Scheme (SRES) for rooftop solar systems from the current 100kW limit to systems up to 1MW.

The proposed changes are expected to commence from 1 October 2026, subject to the required legislative and regulatory approvals.

If implemented, eligible commercial solar systems larger than 100kW may have access to upfront Small-scale Technology Certificate (STC) incentives that were previously unavailable to systems of this size.

For businesses with enough electricity consumption and available roof space to support a system larger than 100kW, this could significantly change the economics of a commercial solar project.

We've covered the proposed changes in more detail in our guide, New Commercial Solar Incentives for Queensland Businesses.

Importantly, though, incentive eligibility shouldn't determine system size on its own.

The right commercial solar system should still be designed around the site's actual energy requirements.

What Size Commercial Solar System Does Your Business Need?

There is no single answer.

A 30kW system may be suitable for one business, while another site could justify 100kW, 300kW or considerably more.

Determining the right commercial solar system size requires looking at the complete picture:

Electricity usage + operating hours + roof space + network requirements + future growth + budget.

That's why copying the system installed by another business — even one of a similar size — isn't necessarily the best approach.

Two neighbouring warehouses can have completely different electricity profiles depending on what happens inside them.

Commercial Solar Installation in Brisbane & South East Queensland

Open Electrical designs and installs tailored commercial solar systems across Brisbane and South East Queensland.

We work with warehouses, manufacturing facilities, offices, retail businesses, agricultural properties and other commercial sites to design solar solutions around their actual electricity requirements.

Our commercial solar assessments consider energy consumption, daytime demand, available installation space, future growth and the site's broader energy requirements before recommending a system size.

As a family-owned Queensland electrical business operating since 2013, our commercial solar installations are completed by our own trained, in-house electricians — with no subcontracted installation crews.

Frequently Asked Questions

What size solar system does a commercial building need?

Commercial solar system size depends on the building's electricity consumption, daytime demand, operating hours, available roof space and future energy requirements. There is no standard system size suitable for every commercial building.

Is 100kW enough solar for a business?

It depends on the business. A 100kW commercial solar system may be suitable for some sites, while businesses with higher daytime electricity consumption may benefit from a larger system.

Can a commercial solar system be larger than 100kW?

Yes. Commercial solar installations can exceed 100kW. The appropriate size depends on electricity consumption, site conditions, network requirements and the economics of the project.

How much roof space does commercial solar need?

The amount of roof space required depends on system capacity, solar panel size, roof layout, orientation, shading and areas that need to remain clear for access or other rooftop equipment. A site assessment is the best way to determine usable solar space.

Should a business install a commercial battery with solar?

Not necessarily. Businesses with high daytime electricity consumption may already use a large proportion of their solar generation directly. Commercial battery storage can become more valuable where excess solar is available, electricity is required outside daylight hours, peak demand needs to be managed or backup power is important.

Plan the Right Commercial Solar System for Your Business

The best commercial solar system isn't necessarily the biggest or the cheapest.

It's the system designed around how your business actually uses electricity.

For Queensland businesses considering commercial solar — particularly systems above 100kW — the upcoming October 2026 changes make now a particularly useful time to assess your site's energy requirements and understand what system size makes sense.

Open Electrical provides commercial solar installation across Brisbane and South East Queensland. Speak with our team about a tailored commercial solar assessment for your business.