Mount Sinai Solar Installation: 20.6 kWp Across a Multi-Face Roof, $6,400 a Year

42 black monocrystalline panels across multiple faces of a pitched metal roof, commissioned and exporting on install day. Here's what a 20.6 kWp system actually looks like at this Mount Sinai home in the Holland corridor, and what it saves.

What was actually installed at this home?

42 black monocrystalline panels totalling 20.6 kWp, rail-mounted flush to the existing profile across several distinct faces of a sloped metal roof in the Holland corridor. No penetrations to the waterproofing layer, and the system was commissioned and exporting on the same day installation completed.

Why does a system this size need multiple roof faces?

42 panels is substantially more than a single well-oriented roof face on most detached homes can hold. Spreading the array across multiple faces is generally how a system reaches this size while keeping each individual panel at a reasonable, unshaded orientation, rather than cramming panels onto one face at a poorer angle.

This is also why total roof area, not just headline system size, is the real starting constraint on how large an installation like this can actually get. A smaller single-face roof simply cannot host 42 panels regardless of budget, which is why roof geometry, not financing, is usually the first real ceiling on a project's size.

How does a multi-face layout affect the electrical design?

Each distinct roof face, facing a different direction, behaves electrically differently through the day, which is why correct MPPT allocation across orientations matters more on a system like this than on a single-face installation. Grouping strings from different faces onto one shared inverter channel would drag the better-performing face down toward the weaker one's output.

A system this size also needs the electrical design to account for real capacity limits, covered in single-phase versus three-phase supply, since a larger system is more likely to approach or exceed what a standard single-phase connection comfortably supports.

How much does this system actually save?

Around $532 a month, roughly $6,400 a year, based on Sunnify's projection for this 20.6 kWp system at the Q3 2026 EMA regulated tariff of S$0.3478/kWh, 25% self-consumption, and an SCT export credit of S$0.2581/kWh. This is close to double the savings of a standard 12 kWp terrace installation, roughly tracking the difference in system size, though the relationship isn't perfectly linear since a household's actual usage pattern also shapes how much of that extra generation converts into self-consumption savings rather than lower-value export credit.

How does this compare to Sunnify's largest documented system?

At 20.6 kWp, this installation sits below the 26.4 kWp, 54-panel system at Berwick Drive, currently the largest residential system Sunnify has recorded. Both share the same underlying constraint: available, well-oriented roof area is what ultimately caps system size on any landed property, large or small, not budget or ambition alone.

What would a similar large pitched roof need to consider?

Confirm your roof's actual usable area across every face before assuming a similar system size is achievable, since orientation and shading vary face by face in ways a single headline roof-area number doesn't capture. See solar on a GCB or bungalow-scale roof for how larger properties are typically approached.

Run the full roof suitability checklist to assess your own roof, and the Sunnify solar estimate to see what a similar system could save on your property.