Solar Panel Cleaning — Our Zero-Compromise Standard
We don’t “sort of” follow the manuals — we exceed them. Mr. Juniper cleans with 0 ppm DI & RO 4-stage filtered water and gentle tools only — no soaps, no hard water, no pressure washers, no rotary brushes. Below: our exact protocol and the OEM sources.
Summary: Our Exact Standards (No Wiggle Room)
- Use 0 ppm TDS de-ionized (DI) water only. We verify on site with a TDS meter.
- Use soft, non-abrasive tools only — microfiber pad or ultra-soft flagged brush. No powered/rotary heads.
- Clean only when the panel surface is < 100 °F (38 °C). We measure with an IR thermometer.
- Hose-level pressure with a gentle fan pattern. Never aim at edges/seals. Maintain ≥ 50 cm (20 in) standoff.
- Always finish with a 0 ppm DI & RO 4-stage filtered rinse. No residue. No spots.
- No soaps or detergents of any kind. Period.
- No water with detectable TDS (anything above 0 ppm). Period.
- No pressure washers or mechanical pressurized spray. Period.
- No rotary brushes, steel wool, blades, scouring powders, or abrasive pads. Period.
- No hot-surface cleaning (≥ 100 °F / 38 °C). Period.
- No air-drying of tap/RO water on glass. Zero exceptions.
Context: Utilities and water labs define “hardness” as mg/L (ppm) CaCO₃ — soft (0–60), moderately hard (61–120), hard (121–180), very hard (>180). We eliminate spotting/mineral film risk by using 0 ppm DI & RO 4-stage filtered water exclusively. The Imperial Valley has over 500 ppm. DI alone wont cut it.
How We Go Beyond OEMs
Water Quality
- Standard: 0 ppm DI & RO 4-stage filtered water (verified).
- Backup: If RO is ever used for pre-rinse, it must be ≤ 20 ppm and is always followed by a 0 ppm DI & RO 4-stage filtered final rinse.
- Tap contingency: Only in emergencies, never allowed to dry; immediate squeegee; followed by DI & RO 4-stage filtered final rinse.
Temperature & Timing
- Clean only below 100 °F (38 °C) panel surface.
- Preferred window: first 2 hours after sunrise or last 2 hours before sunset.
- We pre-mist to equalize temperature and avoid thermal shock.
Tools & Contact
- No rotary action devices, ever.
- Ultra-soft flagged bristles or microfiber; light hand pressure only.
- No dry wiping — glass is always lubricated with DI & RO 4-stage filtered water first.
Spray Control
- Hose-level pressure with gentle fan pattern.
- Never jet seams or junction boxes.
- Even if an OEM allows higher pressure, we stay well below and maintain ≥ 50 cm standoff. We utilize our inline pressure gauge to always check and validate.
Proof & Documentation
- TDS readings recorded on request.
- IR-gun temperature logged on request.
- Before/after photos provided always.
OEM Minimums vs. Our Standard
Many manufacturers allow “some” detergent use or define pressure limits. We choose stricter rules to fully protect your glass, coatings, seals, and warranty position.
- Detergents: Some OEMs allow mild, biodegradable soap or ≤ 10% IPA for heavy bird related issues. We use none. There is no need to introduce anything that might ruin your panels.
- Water pressure: Some OEMs set ceilings. We stay at a safe 60-90 psi.
- Water quality: OEMs prefer DI/RO/low-mineral water (as close to zero as possible). We require 0 ppm DI & RO 4-stage filtered for final rinse.
Exact Sources & Quoted Guidance
Scientific Evidence — No Soap
A Finnish study (University of Turku) found that dishwashing detergents did not restore light transmission after cleaning — even when rinsed with distilled water:SolarQuotes — “Solar Panel Cleaning Study: Ditch Dishwashing Detergent”
“Even though the glass looks clean when cleaned with detergent, its ability to transmit light is significantly impaired… a clean-looking end result does not guarantee optimal performance.”
Trade Publication — No Soap
“While dirty solar panels do benefit from a regular washing to ward off reduced output and efficiency, soap isn’t the answer here.”Solar Power World — “Pro tip: Never use soap to clean dirty solar panels”
SunPower / Maxeon — Cleaning & Maintenance
“Clean the front glass using non-heated potable water with a soft sponge or a seamless cloth… Normal water pressure is adequate. If pressurized water is used, it must not exceed 100 bar (1450 psi) at the nozzle, and the nozzle must be at least 50 cm from the glass… Do not use scouring powders, steel wool, scrapers, blades or other sharp instruments.”Maxeon Safety & Installation Manual (PDF)
First Solar — Module Cleaning Guidelines
“Acceptable methods include low-pressure water… RO water provides the best results… When using hard water, squeegee off to prevent scale… Do not spray pressurized water directly at sealed interfaces… Water pressure must not exceed ~35 bar (500 psi).”First Solar Module Cleaning Guidelines (PDF)
Canadian Solar — Installation & Maintenance
Guidance emphasizes low-mineral water / near-neutral pH, non-abrasive tools, and cautions that rotating brush methods can induce micro-cracks — to be avoided.Canadian Solar Standard Modules Manual (PDF)
Jinko — O&M / Cleaning
Use low-mineral water (DI/RO preferred). Contact cleaning with soft bristles only; no abrasive tools or solvents.Jinko PV Modules Instructions (mirror)
Panasonic EverVolt — Installation & Cleaning
“Use deionized water and a soft sponge/microfiber cloth/soft brush… The use of high-pressure hoses or cleaners is not permitted… Do not use abrasive, acidic, or alkaline cleaners.”Panasonic EverVolt Installation Guide (mirror)
REC — Cleaning Quick Guide / Manuals
“Ideally, de-ionized water should be used… Clean when panels are cool… Avoid high-pressure hoses… Do not use abrasive pads or strong acid/alkali cleaners.”REC Quick Guide to Cleaning (PDF)
Our policy is stricter by design: 0 ppm DI & RO 4-stage filtered water only, no soaps, no pressure washers, no rotary brushes. Independent evidence and industry guidance above support a no-soap approach, and manufacturer documents confirm the use of purified water, gentle tools, low pressure, and protection of edges/seals.
FAQs
Do you ever use soap?
No. We never use soaps or detergents. We finish with a 0 ppm DI & RO 4-stage filtered rinse to ensure zero residue.
Why 0 ppm DI & RO 4-stage filtered water?
It eliminates mineral spotting/film completely. Even “soft” tap or DI water can leave residue if it dries. We require 0 ppm DI & RO 4-stage filtered for the final rinse, every time.
Isn’t low-pressure okay?
Some manuals set pressure limits. We go lower by design: hose-level fan spray only, with ≥ 50 cm standoff, and never at edges or junctions.
How do you prove it?
On request we document TDS readings, panel surface temperatures, and before/after photos for your records or any warranty conversation.