System sizing
What roof orientation and tilt work for solar in South Africa?
True north is the classic SA sweet spot, but north-east / north-west and even east–west splits often win once you care about self-use, TOU and late-afternoon load shedding. Tilt near your latitude (roughly 25–34° across the country) is a solid starting band; flatter roofs still work with the right clamps and drainage. Shade, inverter MPPT layout and export rules matter more than chasing a brochure “perfect north” pitch.
Updated 27 October 2026 · Illustrative ranges — not a formal quote, credit decision or legal advice.
Answer first: Do not reject a quote because the roof is not dead north. An east–west dual pitch can push more energy into morning geysers and evening cooking — exactly when Stage 4 and TOU peaks hurt. Ask for a yield model with your azimuths and a self-use column, not only annual kWh.
Orientation bands (illustrative)
| Facing | Typical pattern | When it helps |
|---|---|---|
| True north | Strong midday peak | Max annual yield; good if you can shift loads or store midday surplus |
| NE / NW | Skewed morning or afternoon | Match school-run / work-from-home / late kitchen peaks |
| East–west split | Flatter daily curve | Self-use and two-MPPT hybrids; less noon export dump |
| South | Materially lower yield | Usually last resort unless bifacial / ground mount maths say otherwise |
Coastal mist, Highveld hail belts and tree lines change the winner. A site survey with shade photos beats a phone compass argument — roof suitability · size a system.
Tilt, flat roofs and carports
Latitude tilt is a rule of thumb, not a law. Low tilt on IBR or concrete needs documented drainage and wind design; carports and ground mounts can aim azimuth when the house roof cannot — carport solar. Bifacial modules on light surfaces can claw back some east–west penalty; treat manufacturer bifacial gains as upside, not the base case — mono vs bifacial.
MPPT layout and shade
Two orientations usually want two MPPTs or careful string design. Mixing a shaded west hip onto a sunny north string is how “cheap” quotes underperform. Microinverters or optimisers are tools for specific shade problems, not a default upsell — ask for the shade report.
Tariff and battery angle
If your metro’s expensive blocks sit in the evening, a north-west bias plus a modest battery often beats a larger due-north array that exports at noon for weak credits. Model self-use first — export vs self-use · Cape Town TOU · monthly savings.
Owner checklist
- Photos of each roof plane with approximate azimuth.
- Tree / neighbour shade at 09:00, 12:00 and 16:00.
- Yield table by plane, not only system total.
- Self-use % assumption written on the quote.
- Roof structure / penetration note for the chosen tilt.
Worked self-use sketch (illustrative)
Suppose a Johannesburg home uses 18 kWh/day with a strong 17:00–21:00 kitchen peak and Stage 4 risk after sunset. A due-north 6 kWp array might print a handsome annual total but dump surplus at noon when export credits are weak. A 3 kWp north + 3 kWp west split on two MPPTs can move more kWh into the afternoon, fill a 5–8 kWh usable pack before evening, and cut the import block that actually hurts. The “worse” orientation on paper can win on the bill — if the installer models self-use, not only yield.
Ask for three columns on the proposal: annual kWh, estimated self-use %, and winter month kWh. If only annual kWh appears, the quote is incomplete — read a quote · winter production.
Inverter, string and export-limit interactions
East–west arrays often want separate MPPTs or carefully matched strings. Export-limit settings (when your metro caps reverse power) interact with orientation: a sharp noon spike from due-north is more likely to hit a limiter than a flatter east–west curve. That is another reason self-use design beats brochure azimuth purity — MPPT · export vs self-use.
Three-phase homes should keep phase balance in mind when one roof plane grows larger than another. Unbalanced PV on a single phase can annoy AMI meters even when total kWp looks fine — single vs three-phase.
Roof structure, wind and penetrations
Steeper tilts and tilted frames on flat slabs change uplift. Coastal wind regions and Highveld thunderstorms both punish skinny quotes that skip an engineer’s note. Penetrations must respect the roof warranty — photograph flashings on install day — roof penetrations · roof suitability.
Hail belts may push thicker glass or different module families; match aesthetics across planes if you care about resale photos — selling with solar.
EV, geyser and heat-pump timing
Wallboxes and heat pumps are movable loads. Pair a west-biased plane with afternoon EV charging or a delayed geyser schedule before you buy another 2 kWp “for winter.” Load management that pauses the charger when the kettle and oven coincide matters as much as azimuth — EV load management · heat pump vs geyser.
Where this sits on the desk
Pair with size a system, panels & inverters, how many panels, and choose an installer. Re-check shade every few years as trees grow — yesterday’s north plane can become today’s morning cut-off.
Common quote tricks on orientation
- Annual kWh only, no self-use %.
- One azimuth assumed for a multi-plane roof.
- “North equivalent” marketing for a south-west hip.
- Ignoring winter shade from a neighbour’s new second storey.
- Export income modelled at import rates.
Cross those out before you compare rand/watt. A slightly dearer east–west layout with honest self-use often beats a cheap due-north string that sells midday power for weak credits — red flags · choose installer.
If your roof is hopeless, price a carport or ground mount as a first-class option, not an apology — structural and municipal rules still apply.
Measuring azimuth without drama
A phone compass is a start; a site survey with roof photos and a simple plan sketch is better. Note magnetic declination roughly if you care about true north, but do not let a 5° argument delay a good east–west design. What matters is documenting each plane so the stringing matches the sales model.
Drone imagery helps on complex hips and valleys. Ask whether the yield file used satellite irradiance for your town or a generic SA average — local files beat national hand-waving — size a system.
After install, compare the first clear-day curve to the modelled shape. A flat noon when you were promised a north peak may mean a string is down or azimuth was mis-labelled — call while snag retention still exists — fault codes · install timeline.
Cape vs Highveld tilt notes
North-facing near latitude tilt remains the default SA yield story, but west-facing arrays can shift production into evening self-use when TOU peaks matter (Cape Town residential TOU). East arrays help morning geysers and EV pre-conditioning. Shade from gables, solar geysers and trees often destroys more yield than a 10° tilt “error” — Cape Town TOU · roof suitability · shade / optimisers.
Carports and ground mounts
When the roof is full or heritage-constrained, carport PV can serve EV daytime charging directly — carport solar · roof space.
Quick questions
Is east–west solar worth it in South Africa?
Often yes for self-use. You trade some annual kWh for energy when you actually consume — especially with TOU or evening shedding.
Do I need latitude tilt on a flat concrete roof?
Not always. Low tilt with proper drainage and ballast/penetration design is common; get the structure note in writing.
Will a south roof ever make sense?
Rarely as the primary array. Consider carport, ground mount or a different plane before forcing south.
Sources
- Solar News 24 — size a system
- Solar News 24 — is my roof suitable?
- Solar News 24 — export vs self-use