Solar on warehouse roofs: what it means for new and existing sheds

By Brenscot Builders | Last reviewed September 2026

A warehouse roof is a large, unshaded surface sitting above a business that uses power during the day. It is an obvious place for solar. The panels and inverters are the simple part. The harder questions are whether the roof structure can carry the array, how it is fixed without causing leaks, and how much the electricity network will let you connect.

The answers are quite different for a new building and for an existing shed.

The short answer

On a new warehouse, tell the structural engineer about solar at the start and it costs little to allow for. The National Construction Code (NCC) now also requires new buildings to be solar-ready. On an existing shed, have a structural engineer assess the roof before accepting a solar quote, because older roofs were not designed for the extra load and may be fragile to work on. In both cases the network connection, which is controlled by Energex in South East Queensland, decides how large the system can be.

What solar does to a roof

• Dead load. Panels, rails, clamps, cabling and trays add permanent weight. Light industrial roofs are designed economically and may have little spare capacity.
• Wind load. Panels change how wind acts on the roof, particularly near edges and corners, and the fixings must resist uplift. AS/NZS 1170.2 (Wind actions), the 2021 edition, includes provisions for roof-mounted solar panels. Tilted arrays attract more wind load than panels fixed flat to the roof.
• Concentrated loads. The load goes into the roof through the rail fixings, not evenly. Rails should be fixed to the purlins. The purlins, usually cold-formed steel designed to AS/NZS 4600, are often the limiting element.
• Penetrations. Every fixing and cable entry is a potential leak. Clamp systems that suit the roof profile avoid many penetrations.
• Access. The installation crew, and later the cleaners and maintenance technicians, need safe access.

New warehouses: design it in

The NCC now requires solar-ready buildings

Under NCC 2022 Volume One, clause J9D5, a new building must have:

• A main switchboard with spare capacity and physical space allocated for a solar photovoltaic system and a battery system
• At least 20% of the roof area left clear for the installation of solar panels

Exemptions apply, for example where solar panels are already installed on at least 20% of the roof, where the roof is no more than 55 m2, where the whole roof is shaded for most of the day, or where more than half the roof is used for something else, such as a car park or roof lights. Clause J9D4 also requires electrical provision for future electric vehicle charging where a car park has 10 or more spaces on a storey. See insulation, condensation and Section J.

Decisions to make during design

1. The target system size and which parts of the roof it will occupy
2. The load allowance the structural engineer should design for across those areas
3. Roof sheet profile and a compatible clamping system
4. Where skylights, vents and exhausts go, so they don't break up the array
5. Inverter and battery location, with ventilation and clearances, and the cable route from the roof
6. Switchboard and supply capacity, and the network connection application
7. Permanent roof access and fall protection

Allowing for solar in the original design costs a fraction of strengthening a roof later. It also avoids working over a finished, warranted roof, and it means fall protection is installed once.

Existing sheds: assume nothing

Older industrial roofs present several problems:

• The original drawings are often missing, so the purlin sizes and spans have to be measured on site
• Roofs were designed for the loads required at the time, with little reserve
• Corrosion at purlin laps, fixings and sheet ends reduces capacity
• Previous additions such as air-conditioning plant, ducting or sprinkler pipework may already have used the spare capacity
• The sheeting may be near the end of its life. Panels are expected to last 25 years or more, so putting a new array on a roof that needs replacing in ten years is poor economics
• Older roofs may be asbestos cement sheeting. It is brittle, must never be walked on, and cannot be drilled or fixed into without licensed asbestos controls. Replacing the roof first is normally the only sensible approach. See asbestos and hazardous materials

Workplace Health and Safety Queensland identifies asbestos cement and fibre cement sheeting, plastic and fibreglass skylight sheeting, and corroded metal roofing as fragile surfaces. Falls through fragile roofing are a well-known cause of death in the construction industry.

A sensible process for an existing building:

1. Engage a structural engineer (RPEQ) with experience in industrial roofs
2. Find the drawings, or measure the purlins, rafters and bracing on site
3. Assess the condition of the sheeting, fixings and structure
4. Check the roof for the panel layout proposed, including wind uplift on the fixings
5. Decide: proceed, reduce or relocate the array, strengthen the structure, replace the roof first, or use a ground or carport mounted system
6. Make sure the solar installer's fixing details match what the engineer has approved

Do you need building approval?

In Queensland, installing photovoltaic solar panels on the roof of a building is listed in Schedule 1 of the Building Regulation 2021 as work that does not need a building approval, subject to the terms of that schedule. That is not the same as having no obligations:

• The work must still comply with the building code. The owner remains responsible for the roof being structurally adequate
• If the roof structure has to be strengthened or altered, that work may need building approval. Ask a building certifier
• Planning scheme requirements can apply in some locations, such as heritage places
• In a leased building, the lease and the owner's consent govern what a tenant may install. In a community titles scheme, the roof is often common property and the body corporate must agree

Electrical and network requirements

• Standards and licensing. The array is designed and installed to AS/NZS 5033 (PV arrays), AS/NZS 4777 (grid connection of inverters) and AS/NZS 3000 (the Wiring Rules), by licensed electrical contractors. To create small-scale technology certificates, the designer and installer must be accredited by Solar Accreditation Australia, which replaced the Clean Energy Council as the accreditation body in 2024.
• Network connection. In SEQ, Energex assesses every solar connection. Inverter systems up to 30 kVA follow a simpler process. Above 30 kVA the system is treated as embedded generation and needs a formal application and technical assessment, interface protection, and a compliance report from a registered professional engineer. Energex may limit the system's size or how much it can export, depending on the local network. Lodge the enquiry early, because it sets the viable system size.
• Emergency backstop. New and replacement inverter systems of 10 kVA or more in Queensland must be fitted with a device that lets the network operator switch the system off remotely in a network emergency.
• Certificates. Systems up to 100 kW are eligible for small-scale technology certificates. The Clean Energy Regulator advises that the small-scale scheme has been expanded to cover solar systems over 100 kW and up to 1 MW installed from 1 October 2026, with further requirements to be published. Get current advice before committing.

Who owns the solar?

On a leased building, decide early whether the owner or the tenant installs and owns the system, how the power is sold or credited, and what happens at the end of the lease. Roof warranties, the make-good clause and access for maintenance all need to be covered in writing.

Frequently asked questions

Can my existing warehouse roof take solar panels?

Possibly. It depends on the purlin size and spacing, the roof's condition and the wind loads at your site. A structural engineer needs to check. Don't rely on the solar company's assurance alone.

Do I need council or building approval for solar on a warehouse in Queensland?

Installing panels on a roof does not itself need building approval in Queensland, but the work must comply with the building code, and any structural strengthening may need approval.

How heavy are solar panels?

The weight depends on the panel, the framing and whether the array is tilted or ballasted. Your installer supplies the actual weights and the engineer checks the roof for them, together with the wind loads, which often matter more than the weight.

Do new warehouses have to be solar-ready?

Yes. NCC 2022 clause J9D5 requires switchboard provision for solar and batteries and, subject to exemptions, 20% of the roof area kept clear for panels.

How big a solar system can I connect?

Energex decides, based on the local network. Inverter systems over 30 kVA are treated as embedded generation and need a formal application and engineering assessment. Note that 30 kVA is a generation threshold. The capacity of the supply coming into the building is a separate question, and large loads are negotiated with Energex in their own right. See power supply and the Energex connection.

Sources

• National Construction Code 2022, Volume One, clauses J9D4 and J9D5, ncc.abcb.gov.au
• Building Regulation 2021 (Qld), Schedule 1
• AS/NZS 1170.2:2021 Structural design actions: Wind actions; AS/NZS 4600 Cold-formed steel structures; AS/NZS 5033 Installation and safety requirements for photovoltaic arrays; AS/NZS 4777 Grid connection of energy systems via inverters; AS/NZS 3000 Electrical installations
• Energex, solar connections and other technologies, and the emergency backstop mechanism, energex.com.au
• Clean Energy Regulator: small-scale renewable energy systems, mid-scale solar, and solar accreditation, cer.gov.au
• Managing the risk of falls at workplaces Code of Practice 2021, WorkSafe Queensland

General information only

This article is general information, current as at September 2026. It is not structural, electrical or financial advice. Have a registered structural engineer assess any roof before installing solar, and use licensed and accredited electrical contractors.

Planning an industrial warehouse?

Talk to Brenscot about your site or your requirements. Call 0480 800 077, email enquiries@brenscot.com.au, or start an enquiry. You can also read how we work.