Is My Roof Ready for Solar? Structure, Condition and Shading Checks

Most Sydney roofs can carry solar panels, but "can" and "ready" are not the same thing. A roof is ready when it will comfortably outlast the panels, its structure can handle the extra load and wind forces, and enough of it sees clear sun through the whole year. Panels are commonly warranted for 25 years or more, so the question to ask before signing is simple: will this roof still be sound, dry and largely unshaded for that long? If the honest answer is "probably not", it is far cheaper to fix the roof first than to remove and reinstall an array later.

Start with the roof's age and condition

Taking panels off for a re-roof is a significant job. The panels, rails and cabling come off, the roof is replaced, and the system is then reinstalled and re-tested by a licensed electrician, with the house running without solar in between. That is why our team inspects condition in person during every site assessment rather than judging a roof from an aerial photo.

What we look for depends on the roof material:

• Concrete and terracotta tiles: cracked, slipped or porous tiles, crumbling ridge-capping mortar or pointing, and brittle tiles that break underfoot. Damaged tiles under the future array can be replaced before installation.
• Metal sheet roofs: rust around fixings and laps, lifted screws, sagging sheets and signs of past leaks. Faded or chalky paint is usually cosmetic; rust that has eaten through the coating is not.
• Flat and low-pitch roofs: membrane condition, ponding water and drainage, because tilt frames add fixings that must be sealed properly.
• Inside the roof space: water stains on timbers or ceilings, rotten battens, and any sagging that suggests the framing is already working hard.

If the roof is near the end of its life, the practical order is re-roof first and solar second. If it only needs localised work, repairs under the array footprint are usually enough.

Repairs to organise before installation

Minor repairs are best completed shortly before installation, so the surface under the panels starts in good shape. Typical items include replacing broken tiles, re-bedding and re-pointing ridge caps, swapping rusted screws or sheets, and resealing flashings. Roof work should always be carried out by qualified trades using proper fall protection, so please do not climb onto the roof to inspect it yourself.

Our energy market lists the related services we coordinate. Prices are indicative and confirmed after a site assessment:

When structural engineering is needed

A typical residential array adds a modest, evenly spread weight, and most sound, conventionally framed roofs carry it without special measures. The bigger force is often wind. Panels behave like a sail, so fixings have to suit the wind region, the building height and the position on the roof, with edges and corners working hardest.

We recommend an engineer's check when:

• the roof framing is undersized, altered, damaged or of unknown construction;
• the array is large, uses tilt frames, or sits on a flat roof where frames change the loads;
• the home is in a high-wind area, on an exposed ridge or close to the coast;
• the building is commercial, strata-owned or an older heritage property;
• a carport, pergola or other light structure is expected to carry panels.

The certification confirms the structure is adequate and specifies fixings and spacing. It can add a little time to the project, but it removes guesswork on exactly the roofs where guesswork is risky.

Shading: the check that changes the design

Shade is the readiness factor people most often underestimate. Panels in a string share current, so shade on part of one panel can pull down the output of others on the same string. Winter matters most. The sun sits much lower in the northern sky, so a tree, chimney, neighbouring second storey or antenna that clears the roof in summer can throw long shadows across it from May to August, when production is already at its lowest.

During an assessment we note obstructions for each roof face and adjust the design: moving panels away from shade, splitting panels across separate inverter inputs, or leaving a shaded section empty. Where a tree is the main issue, a qualified arborist's advice on what can safely and lawfully be pruned may change the layout, so it is worth getting before the design is finalised.

Access, cable routes and the switchboard

A roof can be sound and sunny and still need planning for the installation itself. We check safe access for installers, including scaffolding or edge protection on two-storey homes; clearances around vents, skylights and roof edges; a sensible cable route from the array to the inverter; and a suitable wall for the inverter and any future battery, ideally out of direct afternoon sun. Older switchboards with ceramic fuses or no spare space can also need an upgrade before new solar connects, and that is always shown on the quote as additional work.

Use the roof suitability checker first

Before anyone visits, our roof suitability checker gives a useful first read on orientation, pitch, shading and roof material. Treat it as a filter rather than a verdict: it flags the roofs that need a closer look and helps you arrive at the assessment with the right questions. From there, our residential solar page explains how we move from assessment to design and installation.

Next steps

If your roof is older, has leaked before, or is partly shaded by trees, mention it when you request a quote. We will inspect the roof in person, tell you plainly whether repairs, waterproofing or an engineer's check should come first, and list those items separately so you can see exactly what they add. All design and installation is carried out by SAA-accredited installers and licensed electricians.

Frequently asked questions

Should I replace my roof before installing solar?

Only if it is close to the end of its life or has widespread problems, such as extensive rust, many failing tiles or recurring leaks. Removing and reinstalling an array later adds labour, electrical re-testing and time without solar. If the roof has many good years left and only needs local repairs, fix those under the array area and go ahead. An in-person roof assessment gives you a clear recommendation either way.

Can solar panels cause roof leaks?

A correctly installed system should not. On tile roofs, mounting brackets are fixed to the rafters and sit under the tiles rather than through them, and on metal roofs the fixings use sealing washers into the purlins or battens. Leaks usually trace back to cracked tiles, poor flashing or unsealed conduit entries, which is why damaged areas are repaired first and every penetration is sealed properly.

Can panels go on an asbestos cement roof?

Asbestos cement sheeting is generally not suitable for mounting panels, because drilling, cutting or walking on it can disturb fibres. If your home is older and you are unsure what the roof is made of, say so before any work is planned. The usual paths are removal and replacement by a licensed asbestos removalist before solar, or using another location such as a different roof section, a carport or a ground-mounted array.