Panels & maintenance
How fast do solar panels degrade — and when should I replace them in South Africa?
Updated 26 October 2026
Answer first: Modern crystalline panels in South Africa usually lose a fraction of a percent of output each year — commonly about 0.4–0.8%/year after a larger first-year LID-style drop. A typical 25-year performance warranty still promises roughly 80–87% of nameplate at the end of the term. Replace panels for measured under-performance or physical damage — not because a calendar hit 25. The inverter often needs attention sooner.
Two warranties, not one
| Warranty | What it covers | Typical length |
|---|---|---|
| Product / materials | Physical defects — delamination, junction-box failure, workmanship in the module | Often 10–15 years; premium lines longer |
| Performance / power output | Guaranteed % of nameplate remaining over time | Usually 25 years (some 30) |
Example curves published on SA-sold modules (e.g. GC Solar shop warranty text): ≥95% after 5 years, then ≤0.4%/year so ≥87% at year 25. Other OEM sheets sold locally (e.g. Jinergy schedules on SA distributor PDFs) show first-year caps around 2–3% then ~0.45–0.7%/year depending on mono/poly and glass type. Always read the datasheet on your quote.
What “degradation” feels like on the bill
A 1% drop on a 6 kWp array is only ~60 W of nameplate — usually invisible next to dirt, shade and seasonal sun. Clean and inspect before you assume the modules are dying — cleaning & maintenance. Monitoring that logs kWh vs expected irradiance catches real problems earlier than a once-a-year glance at the inverter screen.
When replacement (or a warranty claim) makes sense
- Independent / installer flash-test or string measurements show output below the warranted curve after ruling out soiling, shading, MPPT faults and wiring.
- Visible failure: cracked glass, snail trails with power loss, delamination, moisture inside the laminate, burnt junction boxes.
- Unsafe mounting after storm damage — fix structure even if cells still produce.
- You need more energy for new loads (heat pump, EV) and roof space is full — then a higher-wattage re-panel can be a design choice, not a failure response.
What usually ages out first
Inverters commonly sit on shorter product warranties and real-world service lives often land around the 10–15 year band before a refresh. Batteries follow cycle/throughput warranties — see warranties and battery guide. Do not strip a healthy array just because the hybrid needs a board swap.
How to check before you panic
- Download 12 months of inverter yield (kWh) and compare summer-to-summer, not January-to-July.
- Wash the array and re-check after a clear week — cleaning.
- Ask the installer for string voltages/currents or a clamp-meter session; rule out optimisers, MC4 faults and shade first.
- Only then talk warranty claim or selective module swap. Mismatched new high-wattage panels on an old string need an engineer’s eye for voltage windows.
Upgrade vs repair economics
Retail energy in 2026/27 often sits roughly R3.30–R4.70/kWh before fixed charges. Recovering 5% lost yield on a small array may be worth less than fixing shade or adding a heat pump. Conversely, if you are about to add an EV and the roof is full of 2018-era 300 W modules, a planned re-panel to modern 550–600 W class can free capacity — treat that as a capacity project, not a degradation emergency. Finance options: solar finance.
SA climate notes
High irradiance is great for yield; UV, hail and coastal salt are the wear factors. Specify hail-rated glass where storms are common, keep earthing/SPD in good order — SPD · earthing — and photograph the array after severe weather.
What a healthy SA system should look like after five years
Quality mono modules commonly warrant ~0.55% or better annual degradation after year one. A 6 kW array that produced 9 000 kWh in year one might still deliver well above 8 500 kWh in year five if cleaned and unshaded — climate and soiling matter. Sudden cliffs usually mean a failed optimiser/microinverter, a string fault, heavy soiling or new shade — not “the panels died of old age.”
Claim pack
- Monthly yield history from the inverter portal.
- Cleaning log and photos of soiling.
- String voltages / IV curve if the installer can run one.
- Original flash-test sheets and serials.
Open the linear warranty only after ruling out invertor clipping, grid outages and new trees. Replacement economics often favour fixing the weak string or adding a few panels when the roof still has space — roof space.
When full re-panel makes sense
Early 2010s thin-film or poorly documented imports, chronic hot-spot damage, or a reroof that needs everything off anyway. Otherwise treat degradation as a slow input to payback, not a panic trigger. Pair with warranties.
Soiling vs true degradation
Coastal salt mist, Highveld dust and inland pollen can look like “dead panels” on a portal chart until someone rinses the glass. Log a cleaning before any warranty claim. If production snaps back, you found O&M, not end-of-life. Maintenance habits: cleaning & maintenance.
Hot spots and micro-cracks after hail
Hail and clumsy foot traffic can create cells that run hot under IR inspection while the portal still looks “almost fine.” If your area had a severe storm, ask for a visual + thermal check before arguing degradation percentages. Insurance may lead; manufacturer warranties often exclude acute physical damage.
Performance warranty maths in plain rand
Suppose a 6 kWp array yields about 9 000 kWh in a good first year on the Highveld. At a 0.5%/year linear fade after year one, year-ten output is still around 95% of that baseline before soiling — hundreds of kWh, not thousands. At 2026/27 retail energy of roughly R3.30–R4.70/kWh, that fade is often less than the cost of one missed cleaning season or a single shaded string. Replacing every module because Instagram said “panels die at 25” usually fails the spreadsheet.
Where the maths flips: measured yield stuck well below the OEM curve after cleaning and shade checks; cracked or delaminated glass after hail; or a planned reroof where labour to remove and reinstall old low-wattage modules exceeds the premium for modern 550–600 W class. Treat those as project decisions with quotes, not calendar panic.
Related
Sources
- SA distributor / OEM performance warranty examples (GC Solar published 25-year curve to ≥87%; Jinergy crystalline module warranty PDF hosted by SA distributors)
- Power Equipment SA explainer — typical 0.5–0.8%/year degradation band and 25–30 year useful life framing
- SolarGuide SA — product vs performance warranty distinction