Automated vegetation management for solar farms

What is automated vegetation management on a solar farm?

It is mowing under and between panel rows with an autonomous machine that positions itself by RTK, runs to a schedule, and does the bulk of the cut without a driver. It is not spraying, not post-collar work and not a replacement for the crew; it takes the repetitive, wide-area cutting off their roster so their hours go to the work that needs people.

Our model is to operate that machine for you, on your ground, against your contract heights. You keep your crew and your existing scope. We add a scheduled cutting cycle that does not depend on who is available that week.

How much of a solar farm can a robot actually mow?

The bulk strip under and between rows, wherever there is at least 75 centimetres of clearance. That is the part of the site where a robot beats a ride-on outright, because a ride-on cannot get under the modules at all.

The rest is a person. Around posts, cable trays, inverter pads and fence lines, the machine currently stops on contact and alerts rather than working its way around. Post detection in tall grass is a known limit on the current firmware, and an upgrade is targeted for the end of 2026. Until it lands, we scope close-in work at 60 to 70 percent autonomous and put the remainder on the crew's roster in writing. Anyone who tells you a site is fully autonomous has not walked one.

Contract heights are the measure. Most solar vegetation contracts specify something around 100 millimetres under panels. The machine cuts to that, and the cut records show where it did.

How many machines does a site need?

Divide mowable acres by the planning figure, then check the answer fits inside your mowing cycle with slack for weather. Most solar vegetation contracts work to a cycle, commonly the whole site cut to height every 30 days, so the question is whether the fleet can cover the site and be back at the start before the clock runs out.

A worked example on a fictional site. Take 500 mowable acres. At about eight acres a day, that is roughly 63 machine-days to cut the lot. One machine takes two months and fails the cycle. Three machines do it in about 21 days, inside a 30-day cycle with roughly nine days of slack for rain, recovery and a wet corner that has to wait.

That slack is the whole point. Spring growth roughly doubles the rate, so a fleet sized for winter fails in September. Size for the flush, not the quiet month.

What about fire?

The machine has no spark or fire detection. It has overheat protection for its own components, which is a different thing, and we will not present one as the other. Fire risk on the site is managed operationally, not by a sensor.

The controls are the ones a site manager would recognise. No-go zones on gravel margins and hardstand, where a blade strike is possible. Charging stations sited on cleared ground with a spacing plan, not against a fence line in long grass. No charging on total fire ban days. And the thing the machine does contribute: a consistent cut height across the whole site, every cycle, which is fuel-load control that does not slip when the crew is short in February.

Battery chemistry is a legitimate selection question on fire-prone ground and we answer it in writing before a trial, along with a one-page battery and fire management plan for the site.

Does the positioning hold between panel rows?

Positioning is RTK from a base station on site, over local radio, accurate to about two centimetres. Metal panels reduce radio range to roughly a kilometre, so a large site runs several bases rather than one. Short dropouts are ridden through for a few minutes; after that the machine stops rather than guessing, and alerts.

If RTK is new to you, how RTK positioning works and how it is installed covers the base station, the correction signal and what a survey involves.

Long straight rows are the easiest geometry there is for RTK line-following. Long-row tracking over hundreds of metres is still something we prove on your ground before we rely on it, because row length and radio conditions vary by site. That is what the trial is for.

When does it mow?

Whenever the site is quiet. RTK and LiDAR do not need daylight, so the machine can run overnight when there is nobody else on the ground and finish before the day crew arrive. Nothing is waiting on a contractor's calendar.

Queensland summer needs a protocol, and this is it. Extreme heat is hard on every electric machine, and the honest failure on a very hot day is that the machine protects itself and parks, which costs coverage rather than damage. So summer cycles run at night and early morning, with the machine on hardstand through the worst of the afternoon. Night mowing makes that free.

Wet ground, and sheep

Wet or waterlogged ground is mapped out, not driven through. A heavy machine on saturated turf damages the turf and the schedule, so wet corners wait for the dry and the rest of the site keeps moving. In the wet season the compliance risk lives in January, not July, and the schedule is built for that.

Grazing is a complement, not a competitor. Sheep take the flush down and leave the close-in and the under-panel strip, which is exactly where the machine works. If you graze, we plan around it.

What does it cost?

It depends on the site, and we quote after a site assessment rather than off a map. The drivers are mowable hectares, growth rate, contract height, terrain, panel clearance, access and trailering between zones, fire controls, wet-weather exclusions, edge work, and how many cycles a year the site needs. The lowest day rate can be the most expensive option once mobilisation and missed cycles are counted.

Compare a full season against the required standard, not a single cut. Bring what you spend on vegetation now, including the crew hours that never appear as a mowing line item, and we put both numbers side by side.

For how a solar site compares with other commercial ground, see the commercial robotic mower buyer's guide.

What the site assessment checks

We walk the mowable zones and the exclusions. Panel clearance, cross-braces, posts and cable trays. Slopes, surface condition, wet areas, access and where a trailer can get to. We test positioning and radio conditions in the actual rows. We identify charging, hardstand and fire-control locations, separate the bulk mowing from the close-in manual work, and measure it all against your contract height and cycle.

The assessment can conclude that a site, or a zone of it, is not viable. That is a useful answer and we give it plainly. If it is viable, the next step is a paid trial: defined zones, two full cut cycles, measured against your heights, photographed, and written up either way.

Who does the work?

Your crew, and a technician. The machine takes the repetitive bulk cutting; a trained local technician runs it, swaps blades and packs, unbogs it, and keeps the records. That is a skilled role the site did not have before, and it is how the operating model works whether the technician is ours or yours. The close-in work stays with the people who already know the site.

AutoAcre is an autonomous mowing operator based in the Northern Rivers, NSW, focused on solar-farm and commercial vegetation management. If you manage solar ground and want the honest numbers for your site, get in touch: ben@autoacre.com.au.