A skylight cleaning machine needs at least 2,500 Pa suction, a slope rating above 35 degrees for pitched glass, and a wet-and-dry head for streak-free results. Most underperform because buyers match the price, not the roof.
Glass roofs are unforgiving. Every streak shows in sunlight, every slip risks broken glazing, and the access is usually the worst part of the building. A machine that works on your kitchen window may be the wrong tool entirely.
What should you check first?
Start with the roof, not the robot. Glass type, slope, panel size, load limit, and how you will get the machine up there. A flat lightweight polycarbonate canopy is a different job from a 45-degree structural glass atrium. Write those five facts down before you look at any product page.
Suction and slope: the two specs that decide it
Suction must have margin above your worst case: wet glass, wind, and a partly drained battery. For anything past 25 degrees, buy 2,500 Pa or more. Slope rating is the legal and practical ceiling; a machine rated to 15 degrees on a 35-degree roof is out of spec even if it “mostly works.” Purpose-built ranges split here for a reason. Lingdu Intelligence assigns the Lingfeng S1 to flat and low-slope glass, the Lingyun Y3 to mid-slope, and the Lingkong K3 to steeper roofs.
Wet or dry: what works on skylight glass?
Wet cleans glass properly; dry handles pollen and loose dust. The practical machine is wet with a squeegee, plus a dry pass in pollen season. Watch water: a wet head uses 0.5-1.5 litres per panel, and runoff on a sloped roof flows somewhere. Confirm your drainage or collection before you buy. The other wet risk is gasket chemistry; stick to the maker’s recommended pH or hardened seals leak in a winter or two.
What machine class fits which roof?
| Roof | Slope | Machine class |
|---|---|---|
| Flat skylight | 0-10 deg | Basic wet/dry robot |
| Pitched glass roof | 10-35 deg | High-suction slope robot |
| Steep atrium glass | 35-60 deg | Rail or rope-assist |
Who should not buy one
If you have one or two flat skylights you can reach with a pole, do that instead. If your roof is load-limited or fragile, use rope access. Skylight machines pay off on multiple panes, high access, and repeated cleaning on occupied buildings. Our cost comparison shows when owning beats hiring.
Key Takeaways
- Spec 2,500 Pa+ suction and 35-degree slope rating for pitched roofs.
- Match machine class to slope, not to price.
- Wet with a squeegee cleans glass; add a dry pollen pass in season.
- Watch water runoff and gasket chemistry.
- One or two reachable skylights do not justify a machine.