Rooftop Solar Panels for Commercial Buildings
Bigfisch Projects has installed rooftop solar systems from under 200kWp to over 600kWp across manufacturing, retail and healthcare sites, on tiled, metal and flat concrete roofs alike.
Rooftop solar is the most common embedded PV configuration in South Africa, with many commercial sites already having suitable roof space.
Suitability comes down to three checks: structural load capacity, roof orientation and shading, and roof condition. A site assessment confirms all three before Bigfisch Projects designs your system.
Greencape’s 2025 report identifies rooftop solar. As an initial planning figure, our solar sizing tool allows about 4.4m² per kWp (roughly 227Wp per square metre, using 590Wp panels of about 2.6m² each) and uses the same figure for flat concrete, tiled and metal roofs, ground mount and carports, although usable capacity varies with roof layout, access routes, shading and system design.
Enquire to see if your roof is suitable.
Roof Suitability for Rooftop Solar Panels
Three things determine it: Structural load capacity (can the roof safely carry the panels and mounting), orientation and shading (how much usable sun the roof gets across the day), and roof condition (a roof needing replacement should generally be replaced before, not after, panels go on). A site assessment answers all three for you.
Solar rooftop requirements vary by municipality and network operator. For example, the City of Cape Town guidance highlights structural assessment, electrical compliance, professional sign-off and written authorisation within its supply area. This is not to be assumed across other regions; we can advise you on your specific town or city guidance.
Types of Rooftop Mounting Systems
Not every roof takes the same system; we match the mounting approach to your roof:
- Fixed-tilt systems hold panels at a designed angle to provide consistent year-round generation.
- Adjustable-tilt systems let the panel angle change seasonally to track the sun's shifting path.
- Flush-mounted systems follow the existing pitch of the roof, for a lower-profile install on already-angled roofs.
Attachment depends on the roof surface: ballasted systems use weight rather than penetration, suited to flat concrete roofs, while penetrating systems anchor directly into the structure, standard for metal roofs.
Panel orientation is selected according to the roof geometry, shading, electrical profiles and generation objectives. North-facing arrays can be advantageous in Southern Africa, while East and West facing layouts may be appropriate where site conditions favour them.
Our manufacturing portfolio includes rooftop-suited installations at 158kWp and 644kWp, alongside a 219kWp retail site and a 444kWp healthcare facility.
Designing Rooftop Solar Around Maximum Demand
Peak electricity usage, your maximum demand, can carry its own charges on your municipal bill, separate from total consumption. An energy audit identifies when and where your site hits those peaks, so your rooftop system (and any battery storage) can be sized to reduce them, not just offset general usage.
Book a site assessment with us and we can go through all the options.
When Rooftop Solar Isn’t the Right Option
If your site can’t take the load, doesn’t have enough usable roof space, or you’d rather keep the roof clear, ground-mounted solar or a solar carport are the alternative options.
Book a site assessment with us and we can go through all the options.
Frequently Asked Questions
How much roof space do I need for a commercial solar system?
As an initial planning guide, around 4.4m² per kWp (about 227Wp per square metre, using 590Wp panels of roughly 2.6m² each) may be required. Our sizing tool applies the same figure to flat concrete roofs with ballasted frames, tiled and metal pitched roofs with flush-mounted panels, ground-mounted arrays and solar carports. Actual requirements vary with panel wattage, layout, access routes, shading and mounting design. A site assessment provides the accurate figure.
Does my roof need to be replaced before installing solar?
Only if it’s already near the end of its life. Installing on a roof that needs replacement within a few years usually costs more overall than replacing the roof first, then installing the solar panels.
How long does a rooftop commercial solar installation take?
Project timelines vary with system size, procurement, construction requirements and SSEG grid approval. Many commercial projects can progress from signed proposal to commissioning within a few months, but the actual timeline is site-specific.
How much does a commercial rooftop solar installation cost, and what is the payback period?
Cost depends on system size, roof type and mounting approach; the payback period varies by site. A feasibility study gives you a site-specific cost and payback figure before you commit.
Why does maximum demand matter for sizing my solar system?
Because the maximum demand charge is billed separately from consumption, sizing a system purely on total kWh usage can miss the bigger cost driver. An energy audit is the starting point for getting the sizing right.