Hardware
How much do trees cut solar yield in South Africa?
Even brief midday shade on part of a string can slash that string’s output far more than the shaded fraction of the roof — prune, redesign strings, or use module-level electronics before you buy extra panels to “make up” for a tree you refuse to manage. Model shade with a site survey, not a guess from the driveway.
Updated 27 October 2026 · Illustrative ranges — not a formal quote, credit decision or legal advice.
Answer first: Walk the roof at 09:00, 12:00 and 15:00 across seasons if you can, or insist on a shade survey / irradiance tool output in the quote pack. Winter Highveld sun angles are lower — a tree that “barely touches” in December can wreck June — winter production · cloudy days · shade / optimisers · orientation.
String physics in one paragraph
Modules in a series string share current. One shaded module can limit the whole string unless bypass diodes and MPPT design mitigate it. That is why “only 10% of the roof is shaded” is not “only 10% less energy.” Related: MPPT · string vs micro · DC/AC ratio.
Mitigation ranked by honesty
- Prune or remove the offending canopy (with municipal/estate permission).
- Keep shaded modules off the main unshaded MPPT — separate strings.
- Consider optimisers / micros where shade is permanent and pruning is impossible.
- Last: add more unshaded kWp elsewhere (carport / ground) — carport · ground mount · east–west.
Estate and neighbour politics
Cutting a street tree or a neighbour’s canopy needs permission. Document the shade survey so debates are about kWh, not vibes — estate / HOA · sectional title.
Quote tests
| Ask | Why |
|---|---|
| Shade report attached? | No report → marketing yield |
| Which modules on which MPPT? | Stops mixing shade into the good string |
| Annual kWh with shade case? | Payback honesty — payback |
| Pruning plan named? | Who pays, how often |
Related: read a quote · how many panels · size a system.
Soiling vs shade
Dust and bird droppings are reversible with cleaning; hard shade is structural. Do not confuse the two when yield drops in August — cleaning · bird proofing · monitoring.
Homeowner folder to keep with the CoC
Store the quote annexures, OEM manuals, serial photos, export-limit screenshots and metro reference letters together. When a future technician or buyer inherits the plant, that folder beats scattered WhatsApps — choose installer · selling with solar · warranty transfer.
Re-check fixed charges and tariff codes after any meter change so savings models stay honest — fixed charges · 2026/27 tariffs · metro tariffs hub · bill still high.
Field notes from SA handovers
At commissioning, ask the partner to demonstrate the behaviour described on this page, photograph settings, and confirm NRS-listed SKUs match the invoice. Refuse non-listed gear and export promises that ignore your metro’s live PDF — red flags · NRS list · SSEG · read a quote.
Seasonal shade walks worth doing
Take phone photos from the ridge line or a safe vantage at 09:00, 12:00 and 15:00 near the winter solstice and again in midsummer. Label them. Many “surprise” June shortfalls were visible in a July walk the year before if someone had looked — winter production · cloudy days · orientation / tilt.
Deciduous trees that look harmless in August leaf out in October and clip the shoulder production you needed for TOU self-use. Evergreen street trees move slowly but relentlessly. Write pruning into the annual maintenance budget — maintenance · cleaning.
Bypass diodes are not magic
Bypass diodes reduce hot-spot damage and recover some energy under partial shade, but they do not restore a fully sunlit string’s current. Marketing that implies “diodes solve trees” oversells physics — MPPT · string vs micro · optimisers / micros.
Worked redesign choices
| Situation | Often better move |
|---|---|
| One chimney shade band | Keep those modules on their own MPPT or omit them |
| Neighbour’s tree, no prune rights | Carport / ground plane instead — carport |
| Moving mottled shade all day | Optimisers/micros after costed prune quote |
| East tree, west clear | Weight kWp west / NW for afternoon TOU — east–west |
Related: how many panels · size a system · payback.
Monitoring tells on shade
If one string under-performs every clear morning while irradiance looks fine, suspect shade or a wiring fault before you buy another battery. Compare string-level charts weekly for a month — monitoring · fault codes · add panels.
Estate politics without the drama
Bring the shade photos and a one-page kWh impact note to the trustees. Asking to prune “because solar” without numbers fails; asking to prune because winter Stage cover needs 12% more morning yield is a clearer request — estate / HOA · sectional title · Stage 4 battery.
Finance and payback sensitivity
Shade errors flow straight into payback slides. If the sales yield assumed zero shade and your winter walk shows two hours of chimney clip, recompute years-to-breakeven before you sign. Banks and further-advance desks will not rescue an optimistic brochure — payback · bond finance · is solar worth it · 5 kW cost.
When shade is structural, spending on usable battery kWh for Stage may beat buying shaded modules that never earn their keep — usable kWh · Stage 4 · need a battery?.
Decision checklist before the deposit
- Same one-page brief to every partner: 12 months of kWh or tokens, tariff code, roof/site photos, Stage essentials list.
- Two matched quotes with Incl. VAT grand totals and named SKUs.
- Export-limit and meter plan written while SSEG queues.
- CoC, dual-supply labels and OEM warranty registration named as deliverables.
- Refuse non-listed gear and export promises that ignore your metro PDF.
Cross-check: read a quote · choose installer · red flags · NRS list · SSEG · SSEG cost · fixed charges · 2026/27 tariffs · metro hub · check a quote · get quotes.
After commissioning — thirty-day habit
For the first month, skim the hybrid app every few days: self-use share, unexpected grid import on sunny afternoons, battery SoC floors before evening Stage, and any fault counts. Photograph settings after the first firmware touch. Keep metro statements beside the monitoring export so “savings” stories stay honest when fixed charges move — monitoring · bill still high · monthly savings · SoC settings · Stage strategy · selling with solar · warranty transfer · insurance.
Related reading on this desk
Shade decisions sit next to string design, winter yield and east–west roof strategy. Use those pages when a partner proposes “just add four more panels” into a mottled string — optimisers · string vs micro · winter · east–west · MPPT · panel count · size a system.
Practical SA homeowner notes
Write the open questions from this page onto the site-survey form before anyone quotes. South African installs fail more often on missing paperwork, wrong board placement and ignored metro rules than on brand slogans. Keep Incl. VAT totals, NRS-listed SKUs, export-limit screenshots and CoC deliverables in one folder with serial photos. If a partner cannot show those artefacts at handover, pause the final payment until they can — that discipline protects Stage cover, insurance claims and resale far better than a glossy brochure.
Revisit the live metro tariff PDF and OEM warranty sheet whenever you expand panels, add a wallbox or change prepaid status. Numbers on this desk are illustrative snapshots dated around 27 October 2026; your erf’s fixed charges, feed-in cents and inspection queue are the figures that decide the rand outcome. When in doubt, send the same one-page brief to two installers and compare their annexures line by line rather than their homepage claims.
- Photograph settings after every service visit or firmware change.
- Log Stage SoC floors for two weeks before changing reserve knobs.
- Confirm dual-supply labels still match the as-built single-line.
- Update the insurer schedule when hardware or capacity changes.
- Store monitoring passwords with the conveyancing pack for a future sale.
Quick questions
Will more panels fix tree shade?
Only if the new panels are unshaded — adding modules into a shaded string rarely fixes the bottleneck.
Are micros always required?
No — pruning or string redesign often wins; micros help when shade is permanent.
Does winter matter more?
Yes — lower sun angles lengthen shadows; demand a winter-aware survey.