Solar panel cleaning in Fish Hoek and the South Peninsula
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Do solar panels in Cape Town need cleaning?
Not always. Canadian Solar says panels tilted at 15° or more "generally may not require cleaning", because rain does the job [1]. Cleaning matters more when:
Your panels are flat or nearly flat. Trina says flat panels miss the "self-cleaning" a tilt of 10° or more gives, so they need cleaning more often [2].
Birds use your roof. Droppings don't wash off in the rain [3].
You live near the sea, where salt helps dust stick to the glass [4].
It's been a long, dry summer, or there's building work or a gravel road nearby. Jinko says to clean more often in dusty conditions [8].
Not sure? Send Cobus a photo on WhatsApp and he'll tell you.
When is the best time of year to clean solar panels in Cape Town?
Late spring and summer, the Cape's dry season, when dirt builds up and the sun is strongest.
Only about 16% falls from November to March, with about five or six rain days a month. These are our sums from South African Weather Service averages. Fish Hoek has no published average, but the Peninsula follows the same winter-rain pattern.
You may read that normal summer rain keeps solar collectors clean; Kwikot's solar geyser manual says so, for example [6]. That holds where summer is the rainy season. In the Cape, it's the dry one.
Winter rain helps, but it isn't a full clean. In a CSIR study in Pretoria, light rain sometimes left a muddy film [7].
How often should solar panels be cleaned near the sea in Fish Hoek?
No fixed interval suits every roof. Check your panels, or your inverter app, every six months, and clean when you see build-up.
Panel makers differ. Canadian Solar says panels tilted at 15° or more may not need cleaning [1]. Jinko asks for at least one clean a year, more where it's dusty [8]. Trina tells owners of its panels to shorten maintenance intervals in salty sea air [2].
That study measured salt in the air for concrete-corrosion research, not on panels.
A film, droppings or a dirt line along the bottom edge means a clean will help.
Does salt spray affect solar panels near the sea?
Yes, it can. Salt in sea air settles on the glass and helps hold dust there.
A University of Cape Town study measured airborne salt around the Peninsula for a year [9]:
| Site | Distance from the sea | Airborne salt (chloride), milligrams per m² per day |
|---|---|---|
| Granger Bay (Atlantic) | 50 m | 138.1 |
| Muizenberg (False Bay) | 150 m | 30.7 |
| Bellville (inland) | 13.5 km | 11.8 |
The study measured salt in the air for concrete-corrosion research, using rain-shielded collectors. It did not measure salt on solar panels. Muizenberg, the station nearest Fish Hoek, is not a Fish Hoek reading.
The International Energy Agency (IEA) explains why salt sticks: salts in dew dry and recrystallise, cementing dust to the glass [4]. That's why a salty film can survive light rain. Trina advises shorter maintenance intervals in high-salinity marine areas [2].
Do bird droppings wash off in the rain?
No. A study of 186 rooftop solar sites in California found that rain doesn't remove bird droppings, and that they "should be cleaned" [3].
Droppings can also cause hot spots. At Eskom's Rosherville research plant in Johannesburg, a cell under a dropping ran 11.1 °C hotter than its neighbours [10]. A cell behind a dirt line along the bottom edge ran 18.4 °C hotter. The researchers warn that long-term partial soiling can cause irreversible damage. LONGi says long-term shading can damage cells through permanent hot spots [11]. Canadian Solar says hot spots from poor maintenance void its warranty [1].
Cleaning helps protect your panels from hot-spot damage caused by bird droppings and dirt build-up. We lift droppings with purified water and a soft brush, never a scraper.
How much power do dirty solar panels lose?
It depends on your roof. We found no published study that has measured it in Cape Town.
The IEA's solar research programme calls dirt the most influential factor on solar output worldwide, after sunlight itself. It estimates dirt cost at least 3–4% of global solar energy in 2018, mostly at large plants [4, 12]. Your own loss depends on your roof, location and the last rain.
South African studies have measured anything from about 1% to about 15%, depending on the site and season:
| Study | Loss | Conditions |
|---|---|---|
| CSIR, Pretoria [7] | About 15% over a dry winter | A ground-mounted test system close to the ground, next to a highway, after about three months without rain on the Highveld. Not a rooftop, not Cape Town. |
| Kalkbult, Northern Cape [13] | About 1% in the worst month | A large, semi-arid inland plant. Heavy rain restored the modules. |
| Cape Town or Western Cape | Not measured | No published study found (October 2026). |
Cleaning restores output that dirt has taken; it doesn't add more.
How do you clean solar panels without damaging them?
We follow the panel makers' own rules. JA Solar, Jinko, LONGi and Trina all forbid standing on their panels [2, 8, 11, 14]. All five makers we checked, Canadian Solar included, call for soft cleaning tools and restrict chemicals [1, 2, 8, 11, 14].
We never walk or kneel on your panels. We clean them with water-fed poles and soft brushes.
Soft brushes, never scraping. Canadian Solar warns that rubbing dirt off dry causes micro-scratches [1].
Purified water, with no soap or detergent residue. JA Solar bans acid and alkali cleaning agents [14].
Cool glass. Cool water on hot glass can crack it. LONGi says to keep the water within 10 °C of the panel's temperature [11]. Jinko says to clean early morning or late afternoon, when the panel is cool to the touch [8]. So we clean your panels when they're cool.
Wind matters too. Trina says not to clean its panels in wind above Beaufort 4, a moderate breeze of 11–16 knots [2, 15].
Canadian Solar and Trina say damage from improper cleaning voids their warranty [1, 2]. We clean the way their manuals describe.
Read why Cobus cleans with purified water and soft brushes.
Wondering how your roof would be reached? Send Cobus a photo on WhatsApp.
WhatsApp Cobus for a quoteIs Cape Town tap water bad for solar panels?
No. Cape Town tap water is soft, and well inside the limits panel makers set.
Hardness in the supplies serving our area was 22–46 mg/L in 2024/25 and April–June 2026, according to the City of Cape Town [16, 17]. The USGS counts 60 mg/L or less as soft [18]. LONGi's hardness limit is 450 mg/L and Trina's is 600 mg/L [2, 11]. No panel maker we checked requires purified water [1, 2, 8, 11, 14].
We still use purified water, because tap water here carries about 60–260 mg/L of TDS (total dissolved solids, the minerals in water) [16, 17]. Those minerals dry as spots. Purified water has almost no dissolved minerals, so it dries without mineral spots and needs no soap or detergent [19].
What's not included in a solar panel clean?
Repairs, electrical work, inspections and anything above double-storey aren't part of the job.
If we see cracked glass, we leave that panel alone and tell you. Trina and Canadian Solar say cracked panels must not be wet-cleaned, because it's an electrical risk [1, 2].
We don't do:
Roof repairs.
Electrical work on your solar system.
Wet-cleaning of cracked panels.
Inspections, tests or reports. If output drops and the panels look clean, ask your installer.
Anything above double-storey. We clean single- and double-storey buildings only.
How is the price for solar panel cleaning worked out?
Solar panel cleaning costs from R45 per panel. The price depends on the number of panels, single- or double-storey and access, the distance from Fish Hoek, and how dirty the panels are.
Every quote is all-in. Travel is included, and Cobus agrees the price with you on WhatsApp, from your photos or a short video, before any work starts. Nothing is added on the day.
Bigger jobs and regular cleans can be discounted; just ask. Maintenance plans are available on request, with the terms agreed in writing. No VAT is charged; we're not VAT-registered.
See how quotes work on our solar panel cleaning prices page, and check Fish Hoek and the other areas we cover.
You can also ask Cobus to clean your solar geyser collector on the same visit, or to have your windows done on the same visit. List everything in one WhatsApp message, and he'll tell you whether it can all be done in one visit and quote for the whole job.
Last updated: 8 October 2026
Frequently asked questions
How often should solar panels be cleaned in Fish Hoek?
No fixed interval suits every roof. Check your panels, or your inverter app, every six months, and clean when you see a film, droppings or a dirt line. Flat panels and homes near the sea tend to need it more often. Canadian Solar says panels tilted at 15° or more generally may not need cleaning.
Will winter rain clean my panels?
Partly. In a CSIR study in Pretoria, heavy rain often reset the dirt loss, but light rain sometimes left a muddy film. Rain doesn't remove bird droppings, and salt that dew has cemented to the glass can survive light rain.
Do you walk on the panels?
No. JA Solar, Jinko, LONGi and Trina all forbid standing on their panels, and we never walk or kneel on them. We clean them with water-fed poles, soft brushes and purified water.
Do you use soap or chemicals?
Solar & Window Clean uses no soaps or detergents: just purified (reverse-osmosis) water and soft brushes. Purified water has almost no dissolved minerals, so it dries without spots and leaves no soapy film. Panel makers restrict cleaning chemicals; JA Solar, for example, bans acid and alkali cleaning agents.
What if my panel glass is cracked?
We don't wet-clean panels with cracked glass. Trina and Canadian Solar say cracked panels must not be wet-cleaned, because it's an electrical risk. If Cobus sees cracked glass, he leaves that panel alone and tells you. For repairs or a replacement, contact your solar installer.
How is solar panel cleaning priced?
Solar & Window Clean charges from R45 per panel. The price depends on the number of panels, single- or double-storey and access, the distance from Fish Hoek, and how dirty the panels are. Every quote is all-in, including travel, and agreed on WhatsApp from your photos or video before any work starts. Nothing is added on the day.
Will cleaning increase my output by 25%?
Not as a rule. Cleaning restores output that dirt has taken; it doesn't add more. A large Northern Cape plant lost about 1% in its worst month. A low, ground-mounted test system beside a Pretoria highway lost about 15% after three rainless months. Neither was a rooftop or in Cape Town.
Sources
- Canadian Solar, Installation Manual, PV Modules (IM/GN-EN/2.0) (February 2024).
- Trina Solar, Vertex Series User Manual (UM-M-0002 PP7) (August 2026).
- Mejia, F.A. and Kleissl, J., Soiling losses for solar photovoltaic systems in California, Solar Energy 95: 357–363 (2013). Summary: UC San Diego, Cleaning Solar Panels Often Not Worth the Cost, Engineers at UC San Diego Find (1 August 2013).
- IEA PVPS Task 13, Soiling Losses: Impact on the Performance of PV Power Plants (Report IEA-PVPS T13-21:2022) (2022), pp. 11, 23 and 56.
- South African Weather Service, via the WMO World Weather Information Service, Cape Town: climatological information (1961–1990 normals, Cape Town airport). Monthly data: https://worldweather.wmo.int/en/json/138_en.json. Percentages are our own arithmetic from the monthly normals.
- Kwikot, KwikSol Installation and Warranty Manual (KW_00018) (June 2025), §12.
- Mienie, Basappa Ayanna, Pratt, Roro and Diale (CSIR), The effect of soiling on the PV performance ratio for different PV systems, SASEC 2018, paper 42 (2018). CSIR record: http://hdl.handle.net/10204/10931.
- Jinko Solar, UL 61730 Installation Manual (Edition 2/2026) (2026).
- Alao, O.O., Refinement of air-borne chloride exposure classes for RC structures in the Cape Peninsula, MSc thesis, University of Cape Town (2015).
- Vumbugwa, M. et al., Effects of current mismatch due to uneven soiling on the performance of multi-crystalline silicon module strings, Journal of Energy in Southern Africa 31(1) (2020), doi:10.17159/2413-3051/2020/v31i1a7571.
- LONGi, PV O&M Module Manual, version 2 (January 2024).
- Ilse, K. et al., Techno-economic assessment of soiling losses and mitigation strategies for solar power generation, Joule 3(10): 2303–2321 (2019).
- Øgaard, M.B., Effect of soiling on the performance of photovoltaic modules in Kalkbult, South Africa, MSc thesis, Norwegian University of Life Sciences (2016).
- JA Solar, PV Single-glass Modules Installation Manual (Q/JASO-PMO-012 A/24) (2025).
- Met Office (UK), Beaufort wind force scale.
- City of Cape Town, Annual Tap Water Quality Analysis, 1 July 2024 – 30 June 2025 (2025).
- City of Cape Town, April–June 2026 quarterly tap water quality report (2026).
- U.S. Geological Survey, Hardness of Water.
- Unger, Pure water cleaning: which pure water filter you should use.