Many landed homeowners in Singapore are surprised to learn that integrating solar during a renovation is significantly cheaper than retrofitting later. The truth is that structural, electrical, and roof-planning decisions made at the building or extension phase determine how much a solar system will save over its lifetime.
Homeowners often ask if they should pre-lay conduits for solar even if they do not install panels immediately. The answer is a firm yes. Running a 25 mm PVC conduit from the roof to the electrical riser before plastering walls saves about $1,200 to $2,500 in post-renovation hacking and repainting. It also keeps the inverter cable run clean and concealed.
The roof orientation of a new extension can make or break solar viability. In Singapore’s equatorial location, a roof face that deviates more than 45 degrees from the east-west corridor sees reduced yields, but it is still usable with a parallel string design. I have advised clients rebuilding a semi-detached in Sembawang to rotate the new car porch roof slightly to follow the longer axis, gaining an extra 1.2 kWp of usable array space without extra cost. Small decisions like this at the design stage translate into over $400 a year in savings.
A modern solar-ready home includes passive cooling design, such as ventilated roof spaces and reflective insulation under the roof tiles. When we mount panels, the gap between the panel and roof forms a ventilated channel that enhances passive cooling. We measured a 2-degree drop in attic temperature on a project where the homeowner also installed a radiant barrier. The combined effect reduces air-conditioning load, which complements solar generation nicely.
Planning a solar-ready renovation
Roof loading and structural reservations
If you are adding a second storey or a roof terrace, inform your structural engineer to reserve an additional 20 kg/m² dead load for future panels. This costs nothing in concrete and rebar, but retrofitting an under-designed slab later requires costly carbon fibre reinforcement. The Building and Construction Authority’s guide on existing building structures (see reference) encourages this forward planning. I have personally turned down jobs where a new attic floor could not hold even a lightweight array because the engineer had designed right at the code minimum.
Pre-installed trunking and cable routing
Solar cables are thick, typically 4 mm² or 6 mm² PV1-F double-insulated, and cannot share the same conduit as 230V AC wires per SCDF fire safety rules. Lay a dedicated 50 mm diameter GI trunking from the roof down the outside wall or inside a service duct before the walls are sealed. Ensure it has a draw wire. Once tiles and false ceilings are up, feeding a cable becomes an expensive exercise.
Orientation and shading from new structures
Even a dormer window addition can cast a shadow on the prime roof area. Use a solar pathfinder or SunEye device during the design stage. I recall a client adding a decorative roof finial that would have cut the morning output of three panels by 30%. We repositioned the finial 600 mm southwards without affecting the architecture. It is that granular.
Integrating with home automation and battery-ready infrastructure
If you plan a future battery, leave a dedicated DB slot and a data cable (Cat 6) from the inverter location to the distribution board. The additional cost is under $200 during renovation but prevents wall hacking later. Many hybrid inverters now require an internet connection for monitoring, and a hardwired connection is more reliable than Wi-Fi.
Making a new extension solar-optimised
Roof pitch and material selection
For a new extension with a pitched roof, standing seam metal roofing is an ideal match because it allows non-penetrative solar mounting. It also weighs less than concrete tiles, reducing the overall structural load. If you prefer tiles for aesthetic reasons, pick a flat-profile concrete tile that sits flush and works with universal brackets. The worst combination is a curved Spanish tile that forces the installer to use an expensive custom flashing per attachment.
Location of the inverter and AC isolator
Position the inverter in a well-ventilated, shaded area, ideally near the main switchboard. A car porch ceiling soffit often works, but it must not block the air intake. During renovations, I ask the electrician to allocate a 20A or 32A MCB slot and run a dedicated 6 mm² armoured cable from the inverter location to the main DB. This future-proofs the home for an electric vehicle charger as well, which shares similar wiring infrastructure.
Lessons from real projects
In a typical Marine Parade corner terrace renovation, the owner wanted a roof garden. We designed a pergola structure that doubled as a solar canopy. The steel beams were sized to carry the solar panel weight plus the glass louvres. The result was a 5.2 kWp system on the canopy without touching the house roof. This hybrid approach, where solar is part of the architecture rather than an add-on, is the kind of integration that boosts property value.
Another landed home in the West had a full roof replacement. We specified OSB sheathing with a self-adhesive underlay that acts as a secondary water barrier. The mounting rails were fixed through the underlay using a pre-compressed sealing tape. That roof has a 15-year watertight warranty and the solar attachment points are part of the roof system, not an afterthought.
If you are renovating or extending, the best time to engage a solar consultant is before architectural plans are finalised. Enquire with Akando Solar at that stage; we typically spend an hour reviewing your drawings and suggesting layout tweaks that cost nothing but save thousands in future retrofitting. For more on system options and panel brands, see our Residential solar panel page. As a solar energy company Singapore, we have guided many landed homeowners through build-and-solar integration with minimal rework.
References
- BCA Existing Building Structural Assessment Guide
- SCDF Fire Code 2018 – Chapter on PV systems
- EMA: Solar PV Systems Consumer Guide