FREE QUOTESolar panel installations have accelerated dramatically across Melbourne over the past decade. With electricity prices continuing to climb and federal and state rebates making solar more accessible than ever, it’s become one of the most common home improvement decisions Melburnians make. The roofing side of that decision, however, gets far less attention than it deserves.
Here’s the problem: a solar system is a 25-year investment. The panels carry product warranties of 10–15 years, and performance warranties of 25 years or more. The roof those panels sit on needs to be able to go the distance alongside them — because if your roof needs replacing after the panels are installed, the panels have to come off first. That means paying to remove them, store them, and reinstall them on top of the already significant cost of a roof replacement.
Done in the right order, solar and roofing work together seamlessly. Done in the wrong order, they create an expensive, disruptive problem. This guide covers everything you need to assess on the roofing side before committing to a solar installation.
The Core Question: Will Your Roof Last as Long as Your Panels?
This is the starting point for every conversation between a roofing contractor and a homeowner considering solar.
If your roof is 5 years old and in good condition, the answer is almost certainly yes — proceed with solar, and the two investments align comfortably. If your roof is 20 years old, showing signs of corrosion, and has a history of minor leaks, the answer is almost certainly no — replace the roof first, then install the panels.
The difficult cases are in between. A 12-year-old Colorbond roof in reasonable condition might have another 20–30 years of life ahead of it — or it might be approaching the end of its serviceable period depending on quality of installation, maintenance history, and local environmental conditions. Only a professional roof assessment can answer that question accurately.
The cost of getting an inspection before committing to solar is trivial compared to the cost of removing and reinstalling panels mid-project. Our post on the hidden costs of delaying roof replacement illustrates how deferring roofing decisions compounds costs — and the solar scenario is one of the most costly versions of that pattern.
Roof Age and Condition Assessment
Different roofing materials have different lifespans, and understanding where your roof sits in that arc is the foundation of the decision.
Colorbond and metal roofing is the most solar-compatible roof material in Australia. A well-installed, well-maintained Colorbond roof can last 50 years or more, meaning a roof installed 15 years ago may well have decades of life remaining. The key variables are installation quality, maintenance history, and local environment — coastal properties age faster than inland ones due to salt exposure.
Concrete and terracotta tiles have a nominal lifespan of 50+ years for the tile itself, but the bedding and pointing at ridges and hips typically needs attention every 15–20 years, and cracked or slipped tiles are common on roofs over 20 years old. A tile roof in poor condition is a significant consideration before solar — tiles need to be in sound condition for installers to walk on safely, and cracked tiles beneath solar panels are difficult to identify and replace.
Asbestos cement sheeting (fibro roofing) — still present on many Melbourne homes built before the 1980s — is not an appropriate substrate for solar panels and should be replaced before any solar installation. Drilling into asbestos cement to mount panel brackets releases fibres that create a serious health risk for installers and occupants.
If you’re not certain of your roof’s age or condition, a professional inspection before booking your solar installer is the most important step you can take.
Structural Load: Can Your Roof Handle the Weight?
Solar panels add load to your roof structure — typically around 15–20 kg per panel, which across a standard residential system of 10–15 panels means 150–300 kg of additional distributed weight.
For most homes built in the last 30–40 years, this is well within the structural capacity of the roof frame. For older homes — particularly Victorian, Edwardian, and Federation-era properties with original timber framing — the calculation is less straightforward.
Original roof framing on pre-1950s homes was designed to carry the loads of the time, which often included heavy terracotta tiles. Many of these homes already carry significant structural loads, and adding solar panels to a frame that hasn’t been assessed is a risk. In some cases, additional strutting or reinforcement of specific rafter spans is needed before panels can be safely installed.
Your solar installer should be assessing structural load as part of their site survey. If they’re not, ask them directly. For older homes, having a roofing contractor or structural engineer review the framing before installation is good practice.
Roof Pitch and Orientation
Solar panels produce the most energy when they face north and are angled at roughly 15–30 degrees to the horizontal in Melbourne’s latitude (approximately 37° south). This is a useful frame of reference when thinking about where panels will go on your roof.
Roof pitch directly affects panel angle. A roof with a pitch of around 22–26 degrees — which is common across Melbourne’s post-war residential stock — provides close to an ideal panel angle without any tilt-frame modification. A flatter roof may require tilt frames to achieve an acceptable angle, adding to installation cost but also creating more surface area beneath the panels where debris can accumulate.
A very steep pitch (above 35 degrees) doesn’t disqualify solar, but installation becomes more difficult and costly, and wind loading on the panels increases.
Our post on why roof pitch matters covers pitch in the context of roofing more broadly — worth reading if you’re also considering a roof replacement at the same time.
How Solar Panels Are Mounted: The Waterproofing Question
This is the aspect of solar installation that matters most to roofing contractors, and the aspect that solar installers sometimes don’t give enough attention to.
Mounting solar panels requires penetrating the roof surface — whether through roof sheets on a metal roof or through tile courses on a tiled roof. Each penetration is a potential water entry point if not correctly sealed and flashed.
On Colorbond and metal roofs, panels are mounted using brackets that bolt through the roof sheet into the batten below. The penetration point should be sealed with a waterproof flashing collar or butyl sealant rated for metal roofing. Flashings should be formed in compatible metal — not aluminium in direct contact with steel, which can cause galvanic corrosion — and should be installed to direct water over the mounting point rather than around it.
When this is done correctly, a metal roof with solar panels is as watertight as one without. When it’s done hastily with inadequate sealant and no flashing, it becomes a source of leaks that can be extremely difficult to diagnose and trace after the fact.
On tile roofs, mounting brackets replace individual tiles and are bedded in the tile course. This requires careful removal of tiles around the bracket location, bedding the bracket correctly, and sometimes repointing the surrounding tiles. Broken tiles during installation — which happens on older, more brittle tiles — need to be replaced immediately.
If you have a Colorbond roof and want to confirm that your solar installation was correctly flashed and sealed, an ELR Roofing roof inspection can assess the mounting points as part of a broader roof condition check. Issues caught early are far easier and cheaper to resolve than leaks that develop months or years after installation.
The Colorbond-Solar Relationship
Colorbond is widely considered the most solar-compatible roofing material, for several reasons:
Lightweight. Colorbond sheets are significantly lighter than tile, meaning less structural load and easier panel mounting.
Continuous surface. A metal roof surface gives solar installers consistent, predictable material to work with — brackets can go anywhere along the sheet length without the constraints of tile courses.
Long lifespan. A quality Colorbond roof can outlast multiple solar system generations, meaning a replacement cycle won’t be triggered mid-panel-warranty.
Compatible with rail-based mounting systems. The most common commercial solar mounting systems are designed around metal roofs, making installation faster and more reliably waterproof than on tile.
There is one compatibility consideration worth knowing: aluminium solar panel frames and aluminium mounting rails in direct contact with Colorbond steel can create a galvanic corrosion pathway in coastal or high-moisture environments. Correct installation uses isolating washers or compatible stainless steel hardware at contact points. If you’re in a coastal Melbourne suburb — Frankston, Mornington, the Bayside area — make sure your solar installer is using appropriate hardware.
What If You Need to Re-Roof After Solar Is Installed?
This is the scenario every homeowner should think through before deciding whether to do solar now or roof first.
Removing a solar system for a roof replacement typically costs $1,500–$3,500 for a standard residential system — covering the labour to disconnect and remove panels, storage during the roofing work, and reinstallation and reconnection. On top of a full re-roofing cost of $15,000–$40,000+ depending on home size, this is a material additional expense.
There’s also the disruption factor. A re-roofing project on a home with solar panels takes longer than on a clean roof — there are additional steps, additional coordination with the solar company or an electrician, and additional risk of panel damage during the work.
The straightforward way to avoid this: assess your roof before you install solar. If it needs replacing, replace it first. The combined project — new roof and then solar — is cheaper and less disruptive than doing them separately in the wrong order.
If your roof needs replacing and you’re planning solar, ELR Roofing can coordinate both the re-roofing and the surface preparation for solar mounting as part of a single project — so the solar installer has a fresh, correctly prepared roof to work on from day one.
Getting the Order of Operations Right
The ideal sequence for a Melbourne homeowner planning solar:
- Get a roof inspection from a licensed roof plumber — not your solar installer — to get an independent assessment of your roof’s condition and expected remaining life.
- Make the roof decision first — replace now, repair and monitor, or proceed with solar as-is — based on the inspection findings.
- If replacing, incorporate solar preparation into the roofing project — correct pitch for optimal panel angle, structural check, clean surface for mounting.
- Then book your solar installer onto a roof that’s been professionally prepared and is fit for a 25-year investment horizon.
ELR Roofing’s team works alongside solar installers across Melbourne on projects where this coordination matters. Our Colorbond roof replacement service can include preparation for solar mounting as part of the scope.
Request a free roof assessment before you commit to a solar installation — it’s the best investment you can make before the larger one.
Related Articles:
- How Long Does a Colorbond Roof Last?
- Is It Time to Replace Your Roof? 5 Signs
- The Hidden Costs of Delaying a Roof Replacement
- Metal Roof vs Tile Roof: Which Offers Better Long-Term Value?
- Does Roof Pitch Matter for Roof Replacement?
- What Is Roof Flashing?