Solar Wash Protect on a Scatec-operated utility plant in Honduras

Scatec, which also has solar plants in South Africa, owns and maintains this utility-scale solar plant in Honduras. Chemitek’s report describes the soiling as fine dirt and dust, seasonal pollen and occasional bird droppings. It says the plant was cleaned with manual brushes about every two months in the dry season, and not at all in the rainy season. Copies of the report give different capacities, so we don’t state one.

• Strings: three, each with the same number of panels.
• CH6: cleaned and protected with Chemitek Solar Wash Protect (SWP), applied by hand: diluted, sprayed, brushed and rinsed.
• CH3 and CH4: cleaned with water only, as two baselines.
• Duration: one month. The report gives no dates.
• Measure: each string’s energy at the inverter. All three saw the same irradiation and ambient temperature.

1. Against water-only string CH31.8%
2. Against water-only string CH42.9%

One month on a utility plant (Chemitek case).

Scatec added an important note: CH6 sat nearer the road and received much more dust than CH3 and CH4, so the result may understate SWP’s effect.

The O&M team found the soiling came off more easily than on the water-only strings, and used much less water, since water was only needed to dilute the product and rinse. Scatec reported that dirt didn’t stick to the treated panels as easily or as quickly. After the test, the O&M team moved all its cleaning to SWP.

How to read it. This is a short test on three strings, and the treated string had the dustier position. Beating both controls from there is a useful signal. The two water-only strings also differed from each other, which shows how much strings vary with no treatment at all, and the report gives no comparison of the three strings before cleaning. A season of data on matched strings, with a pre-treatment baseline, would pin down the size of the gain.

• Rare cleans. Infrequent cleaning is common here too. How often South African IPPs wash is in soiling losses in South Africa. When cleans are rare, a clean that leaves panels resisting new dirt matters more.
• Roads and dust. Strings near a road can soil much faster, as Scatec found. Soiling is not uniform across a site, so test and control strings must be matched for exposure, not just panel count. See soiling ratio, rate and loss explained.
• Water. SWP needed water only to dilute and rinse. Chemitek’s general figure is up to 50% less water than water-only cleaning. Measure it on your own plant before you count on it; see low-water cleaning.
• Warranty. Solar Wash Protect carries letters of conformity from module makers, valid when it is used within each maker’s cleaning conditions. We check your modules’ manual before any product touches the glass; see cleaning and your module warranty.
• Pilot design. We match test and control strings for dust exposure and irradiance, and record a baseline before the first treatment. Book a free pilot to see the difference on your strings.