Restore → Protect → Maintain

Cleaning alone treats the symptom. If a contaminant has cured onto the glass, water won’t shift it. If nothing slows it bonding again, the plant soon needs the same hard clean. So the programme splits the work into three jobs, in order: restore the glass, protect it, then maintain it at the lowest cost.

Which phases a plant needs depends on whether you have soiling or contamination.

1. 1Restore

   Remove bonded soiling

   Typical product

   Inorganic Removal Agent, Lichen Removal Agent or Metal Oxides Removal Agent

   How we check it

   String current or inverter output against control strings

2. 2Protect

   Slow re-soiling

   Typical product

   Antistatic Solar Armor 2.0 or D-Solar Defendor

   How we check it

   Soiling rate before and after, on a soiling sensor

3. 3Maintain

   Keep output high at the lowest cost

   Typical product

   Solar Wash Protect in treated water

   How we check it

   Soiling ratio, water use and crew time per clean

Restore is a deep clean with the removal agent that matches the contaminant found in the soiling assessment:

• Cured cement, stone dust, gypsum or hard-water stains: Inorganic Removal Agent. Chemitek’s datasheet starts at 1 kg in 2 L of water, strengthening to 1:1 or 1:0.5 if needed. It goes onto dry glass, is brushed in without adding water, then rinsed off thoroughly.
• Lichen, moss or fungi: Lichen Removal Agent at 1 kg in 10 L, left for 10–20 minutes, then brushed and rinsed.
• Rust and metal oxides: Metal Oxides Removal Agent, starting at 1:10 and strengthening to 1:5 if needed.

Where the source keeps producing dust, as beside a cement works, lighter follow-up treatments go into the calendar.

Protect coats the clean glass so new soiling sticks less:

• Antistatic Solar Armor 2.0 is dosed at 1 kg per 1,000 L into the cleaning water of a rotary brush, robot or tractor, with no rinse. Chemitek states at least a year of protection, and up to 50% less water.
• D-Solar Defendor is a hydrophobic alternative, dosed at 1 kg per 1,000 L of soft water.

The first coat must go onto fully clean glass, which is why Restore comes first. Coatings are also site-specific. Long-term field averages show 20–50% less soiling, not the 80% or more of short tests (Ilse et al. 2019), and in a Northern Cape trial a hydrophobic coating increased dust soiling (du Plessis et al. 2020). The Morocco field trial compared three Chemitek products through a dry season. That is why we prove Protect in a pilot before it goes plant-wide.

Maintain holds the plant at its restored output for the lowest cost:

• Solar Wash Protect cleans and leaves an antistatic, anti-adherent layer that lasts about six months (Chemitek). SWP 50 is diluted 1 kg to 50 L and applied at about 150–200 mL/m².
• Treated water. Where the water is hard, Water Softening Agent stops each rinse leaving scale.
• A calendar and a crew procedure, set from soiling data and cleaning economics, with a method statement your O&M crew can follow.
• Measurement. A soiling sensor shows when protection is wearing off and the next wash has earned its cost.

Chemitek’s field cases follow the same order, and each phase has its own evidence:

Our own North West pilot started with Restore too, and the programme we designed for that plant runs all three phases on a 24-month calendar.