Window cleaning robots – sparking windows can be easy (update 2023 cleaning guide)

03/07/2023
By Ray Shaw
In Guides

Window cleaning robots are supposed to take the drudgery and effort out of window cleaning. Overall, they do the back-breaking work, but we found some exceptions to that supposition.

What is a consumer-grade window cleaning robot?

It is a reasonably self-contained device that attaches to indoor and external windows and methodically cleans the glass pane before being manually moved to the next. It

Is lightweight enough to stay on the glass by vacuum (avoid magnet-based units as these can scratch glass)
Uses a combination of downward pressure on a fixed platten or rotating cleaning pads and cleaning fluid to remove grime and dirt.
May have an app or remote control.
Is externally powered (avoid battery-operated cleaners as these are more prone to falling off).
Has safeguards against loss of adhesion and falling (death dives).
Can handle a variety of glass surfaces/types/conditions.

How to assess a consumer-grade window cleaning robot?

In a previous review life, I was exposure to Window cleaning robots and have been using one for the past two years. Given that these parameters are tempered by actual use, we convened our user panel to see what they expected.

What users want

Effectiveness. Are they better than manual cleaning?
Speed. Are they faster than manual cleaning?
Questions on type – rotating brush versus a vibrating platen style.
Vacuum or magnetic adhesion?
Internal battery or external power source.
Fail-safe for loss of power and adhesion.
Durability in case of a fall.
Quality of cleaning. Does it clean 100% or leave marks or streaks?
Use on glass with flyscreens or security grills.
Cost of cleaning solution.
Most wanted something that would eliminate manual labour.

The panel concluded that robot window cleaners do a reasonable job. Still, they are by no means unattended cleaning, as there is a constant need to move the device to the inside/outside and new glass panels, clean the pads, fill the cleaning solution and touch up edges.

Shape/Size/Style

There are two main shapes of window cleaning robots. We will call these WCRs for now (as ECOVACS has trademarked WINBOT).

Square style with a microfibre pad ‘drags’ over the glass (not unlike a flat plate-style robomop). Some use vibration to enhance cleaning.
Round style with rotating cleaning pads (not unlike a dual-head robomop).

Both have a fluid reservoir that uses window cleaning fluid and water to cut through grime. Regardless of which one, you must add the human touch by moving it to new panels and touching up any streaks.

Effectiveness

Effectiveness means 100% coverage (corners etc.) and streak-free cleaning. The experience here is that they don’t do corners or edges, and it may be necessary for multiple passes. For example, a dry run to remove dust and a wet run to clean – effectively doubling the time.

Winner: Both types do a similar job

Flat pad or rotating pad

As we found with robomops, the critical issue is changing microfibre pads frequently to avoid dirty wet pads leaving streaks on the glass.

Our experience with the dual rotating Hobot 388 is about 15m2 of wet cleaning before you change pads. Our experience with Winbot is 10-20m2.

Fixed flat pads need more frequent changes as the leading edge tends to do much of the work and gets dirty faster.

Winner: Dual rotating pads appear better and offer more ‘elbow’ grease.

Environment

The jury is out on what produces the best results. The answer is that rotating pads are better for marine and dusty environments as they cut through the salt/dust grime. The overall finish may not be as good as square pads.

Square pads are for suburban use where windows are in better condition and leave the glass cleaner.

Water or Window cleaner

Water is only 40% effective at removing salt spray and environmental grime. A good window cleaner has cutting power and will remove this type of scum.

Don’t use other cleaners as they may block the 15um nano-sprays.

Winner: Use the recommended cleaner

The volume of water or cleaner

Our experience with two Hobot WCRs is that they use a 15um (microns) nano-spray to wet a portion of the window below the bottom pad. It reduces the potential to leave water marks or streaks as there is insufficient volume to wet the pads. The Winbot is similar.

Some WCRs have centre-wetting vents that appear to use a lot more liquid. Less is best.

But also remember that fine spray is subject to the wind blowing it off course. Clean on a still day.

Winner: nano-spray spray over pad wetting.

100% coverage – unlikely

The square type often has triangle cuts at the four edge points, meaning it cannot clean corners. The twin rotating pads cannot reach corners. You will need to clean these areas manually.

Winner – Draw

Vacuum or magnet glass adhesion

Vacuum style creates a vacuum to adhere to glass. These come with a safety rope to stop death dives – great idea but not always convenient.

Magnet mounts use a rubberised magnetic pad on the opposite side of the glass, and the magnets hold the device in place. But there are a few downsides. You may be unable to access the other side of the glass. Magnets strong enough to go through thick glass are heavy. They do not work on thicker glass and are not good on curved glass. The magnet pad can scratch the glass.

Avoid those with larger tractor wheels (generally the magnetic type), as the wheels can leave marks if wet.

Neither type can handle negative slopes (like inside sloping skylights) over 30-45° as the weight and slip factor vectors cross over, leading to the death dive.

Winner: Vacuum suction

Mains power or battery

The Hobot and Winbot are mains powered. The onboard battery acts as an uninterruptable power supply (UPS), giving up to 20/30 minutes of vacuum adherence in case of a power failure. That means you need a 240V power point nearby.

Battery-operated WCRs are heavier and have shorter run times.

The Hobot has a 5m power cord, and the Winbot 4.7m. The battery is small and light, safeguarding against losing mains power. This means it can clean all day without a charging break.

But if you use an AC extension cord, remember that all WCRs can only carry their weight and a few metres of a lightweight DC power cable and safety rope. They cannot hold an AC cord weight, especially if it is lifting it off at an angle to the ground.

Winner: Mains powered

Glass thickness

Some vacuum models can break the thinner 3mm glass. Thicker glass can impact magnetic models. Standard 3-10mm glass is fine.

Winner: Lighter devices are better for thin glass.

Flyscreens and security screens

You must remove screens before cleaning the window surface. Most flyscreens have twist clips, some slip into window frames, and some use magnets. If your home is older, then plan on breaking a few clips.

If you have permanently affixed security screens, the only way to clean the window is to remove it.

Handles, window winders, hinges, locks and obstructions

Take care if anything protrudes into the glass area. Most WCRs will get stuck (those with some AI to recognise this).

Winner: See if AI handles this

Noise

WCRs make a noise – up to 70dB at 1m, and that is fine. Magnetic WCRs are quieter.

Environments

All need dry glass, meaning no rain, snow, or high humidity. Don’t use it on windy or overly hot days.

Winner: Draw

Safety rope

These prevent a death dive after sudden detachment. No WCR can withstand a few metre fall without breaking something.

The real question is where to attach the safety rope, especially for indoor windows where there is only a ceiling overhead.

The answer will only come from experience and confidence with your WCR. If it has had no death-wish issues, perhaps trust it. Why not place a pillow at the window’s base to break its fall?

Winner: Use safety rope where possible, especially outdoors.

Run time and cleaning time

The panel said that WCRs should be faster than doing it with a squeegee.

The Winbot takes 3 minutes per m2, and Hobot 388 takes about 4 minutes per 1m2. You have two sides of the glass and potentially two passes (dry and wet).

Winner: mains power does a more thorough job, but it is slower than a squeegee.

Unattended use

By definition, a robot (be it a vacuum, mop, lawnmower etc.) should be able to be left unattended to do its job. In our experience, no amount of AI or clever navigation means you can leave a WCR unattended.

After every window pass, you need to turn it off, remove the safety rope, move it to the next window and repeat. All types have this issue, and your peaceful time doing other things will suffer regular interruptions.

Winner: Draw, but faster clean times are better

AI versus pattern cleaning

Most WCRs boast AI, but it is just simple pattern cleaning. Place it at the window’s top corner and let it logically clean in a u-pattern as it descends the glass. Odd-shaped glass should not worry these as most use the frame edge to trigger a change in direction.

Frameless glass needs AI detection or a vacuum variance sensor.

But remember that it cannot clean in corners, so you may have to do that manually.

App or remote

Most Apps are just remote controls adding little, if any, functionality to the WCR. A remote control helps stop and move the WCR.

Maintenance and spare parts

Look for models with replaceable water tanks, flat plates, pads, and the sprayer nozzle. Most will have washable microfibre pads.

Winner: Look at better-known brands with good support.

Other uses

Most should be fine on vertical framed or frameless glass, shower screens, tiles etc. But remember that the window cleaner solution probably will not cut through soap, shampoo and conditioner scum. As a rule, if you can easily remove the scum with a damp cloth, the WCR will work.

Are Window cleaning robots worth it?

The cost-benefit is more about being prepared to live with any compromises.

Moving the robot after each window surface.
Frequently cleaning pads
less frequently adding cleaning solution
Manually cleaning edges, corners and around door handles or places it cannot go.
Investing more time in proper window cleaning.

We have experience with:

Hobot 388 (rotating pad type best on dirty windows – now superseded)

Hobot 2S flat vibrating pad is best for windows in good condition.

Hobot-R3 window cleaning robot does a great job rotating pad replacing Hobot 388

Ecovacs W1 Pro shows the latest flat pad technology

You need to use them a few times a year to get any ROI.

This guide will be updated with actual reviews of different brands and models over time.