How the Husqvarna Automower Solar Hybrid Works

The Husqvarna Automower Solar Hybrid is a robotic lawn mower. See more green science pictures.
Photo courtesy of Husqvarna

Dads (and kids and moms, too) rejoice -- you're no longer pulling lawn mowing duty. A 22-pound (12-kilogram) robot can do it for you, whether you're home, away or rained out, for around $3,000. It's kind of like a Roomba but bigger and with three razor-sharp blades. A sign of the mow-pocalypse? Nope, just a sign of lawn maintenance going green.

The Husqvarna Automower Solar Hybrid, designed at the Husqvarna Global Design Centre in Sweden, is a robotic hybrid lawn mower. There are four main components to the automower: its body, charging station, transformer and wire. Its body is made from 90 percent recyclable materials and it's similar in size (although not in shape) to a piece of carry-on luggage, measuring at 28 by 21.7 by 11.8 inches (71 by 55 by 30 centimeters). In comparison, the dimensions of an acceptably sized piece of carry-on luggage are 9 by 14 by 22 inches (23 by 35 by 56 centimeters) [source: United]. The robot is dark grey, too -- again, probably like your luggage.

What makes this mower a hybrid is that while it relies on a rechargeable NiMH 18V battery, it also gets energy from the 12-watt photovoltaic solar cell panel attached to its back. It uses no fuel or oil as a power source. When the sun is shining, the mower uses solar energy instead of battery power. When the battery does need a little juice, the mower automatically finds its way to the charging station via a signal emitted by the station. The mower senses the signal when it's within 20 to 23 feet (6 to 7 meters) of the station. The charging station is electrically powered and connects to a transformer that in turn plugs into a 120-volt wall socket. Overall, the setup uses about the same amount of energy as a standard incandescent light bulb, and adds anywhere from $12 to $25 to your annual electricity bill.

While it may have a lighter footprint than a conventional lawn mower, it doesn't lack in features.

Husqvarna Power and Navigation

By setting guide wires, you ensure your Husqvarna doesn't mow your neighbor's lawn instead of your own.
By setting guide wires, you ensure your Husqvarna doesn't mow your neighbor's lawn instead of your own.
Photo courtesy of Husqvarna

The automower dazzles with its alarm system and programmability, but let's not get ahead of ourselves: First you're probably wondering how to keep it from mowing your flowers or your neighbor's yard.

Before setting the automower loose, you need to set up some boundaries, similar to an in-ground pet fence. The automower comes with a small wire that needs to be buried just below grass level to set predetermined areas in which the robot stays -- these boundary wires limit the mowing area and can be used to set off flowerbeds and gardens. Guide wires also help the mower navigate back to its home base charging station. With the wires in place, the automower's on-board navigation system and ultrasound sensors -- one in front and one in back -- keep an eye on the robot's position.

Within the set boundaries, the automower makes an irregular mowing pattern and crisscrosses the yard until the work is done. Obstacles (or a boundary wire) are handled in two ways, depending on the size of the obstacle. If the mower bumps into a hard object that's at least 6 inches (15 centimeters) tall, such as a tree or a pet, it backs up and starts mowing in a new direction. When the mower encounters boundary wire, its navigation system guides the machine around. Even hills aren't a problem -- the mower can handle up to a 35 percent gradient before it takes a tumble.

Wondering what kind of performance you can expect from a robot mower that's about the size of a French bulldog? The automower's performance depends on the size of your lawn and the available sunlight, in addition to a variety of other things like the type of grass in your yard, how damp the conditions are and how well-maintained you keep the mower's blades. The recommended lawn size is about 0.6 acres (2,100 square meters), give or take 20 percent, and owners can expect their automower to handle about 0.02 acres (87.5 square meters) in an hour. After an hour of mowing, the mower returns to its charging station for a quick energy boost before it heads back out to finish the job. It typically takes about 45 minutes to charge fully.

A homeowner with a conventional power mower can expect to spend about 120 hours mowing that acreage annually -- if you work a 40-hour work week, that's equivalent to spending three weeks of vacation mowing your lawn. How would you rather spend your time?

Husqvarna Automower Features

The mower's 12-watt solar photovoltaic solar cell panel keeps it running fuel-free.
The mower's 12-watt solar photovoltaic solar cell panel keeps it running fuel-free.
Photo courtesy of Husqvarna

All of the mower's settings are managed through an LCD control panel that's housed under the solar cell panel. This is where the mower's settings are customized: The clock, operating mode, mowing hours and program selection (movement patterns) are all programmable. The control panel also displays the battery status and the settings for the mower's anti-theft alarm.

Yes, this little mower is theft-protected, making it safe to program for mowing the lawn while you're not home. Additionally a 4-digit PIN code is set by the owner and required to operate the mower.

It's the novelty not the noise that will draw attention to the automower -- the machine is actually fairly quiet for a mower. The automower's noise level ranks around 63 decibels (dB), quieter than a conventional power lawn mower's noise level of 90 to 100 dB. By comparison, breathing is about 10 dB and a jet taking off hits upward of 150 dB. The Husqvarna is closer to the sound of a hair dryer (70 dB) [source: Dangerous Decibels].

Maintaining the automower is important for good performance. Its battery is maintenance-free and lasts for about 1 to 3 years depending on usage. In addition to regular cleanings, its blade disc and skid plate should be checked and serviced about every 1 to 2 months. Servicing the mower's blades depends on how often you use the mower and the conditions it mows in, including the size of the yard, type of grass and whether or not your yard has leaves, stones, toys or other such items.

When it's not in use, hang the Husqvarna on the available wall mount for indoor storage.

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Sources

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