The most reliable approach to vegetation management under arrays matches method to site type: robotic mowing or string trimming for tight-access rows, sheep grazing for grazable pasture, and strip-mowed native mixes for open sites with vehicle access. Start by inspecting panel clearances and access routes, documenting weed pressure and bare soil, and setting simple action thresholds before you commit to a single method.
TL;DR:
- Motorized mowing is ideal for open, accessible sites but risks panel damage on uneven ground or low-height arrays; strip mowing reduces fuel use.
- Sheep grazing works well in pasture-like areas with fencing and water, but rocky, weed-heavy, or newly seeded sites limit effectiveness.
- Regular monitoring and setting clear thresholds help catch weed or erosion issues early, especially during the first three to five years, when maintenance costs are highest.
- Autonomous robotic mowers excel on tight-access rows with frequent growth but require manual support on steep slopes, densely weeded patches, or near electrical infrastructure.
- Proper site assessment, including weed pressure and soil conditions, is essential before selecting and piloting vegetation management methods, avoiding costly later remediation.
Table of Contents
- Mowing, grazing, herbicide and low-growth alternatives compared
- How should you plan and prepare the site before planting?
- What monitoring schedule and action thresholds actually work?
- Safety, wildfire risk and regulatory obligations
- Balancing biodiversity with panel efficiency
- Where does automation fit into under-array maintenance?
- Quick decision checklist for matching method to site
- The practical future of low-impact under-array management
- How BrightView can help manage vegetation beneath your arrays
- Sources
- FAQ
Mowing, grazing, herbicide and low-growth alternatives compared
Every solar farm ends up choosing some blend of five basic tools. None works everywhere, and the sites that struggle are usually the ones that picked one method and never revisited it.
Mowing remains the default for open sites with vehicle access. Ride-on and tow-behind mowers handle wide row spacing well, but panel-strike damage is the recurring failure mode, especially on sites with low table heights or uneven ground. Strip mowing at 30 to 60 centimetre widths along access lanes, paired with less frequent full-site cuts, cuts fuel use without letting fire-risk grass get away from you.
Grazing with sheep is the preferred livestock option for under-array work. Sheep graze low and evenly, tolerate confined paddocks, and rarely climb or chew on structures the way goats do. You still need robust perimeter and cross-fencing, water access, and a welfare plan for extreme heat. Grazing fails on rocky, weed-heavy, or newly seeded sites where livestock either can’t reach the growth or will selectively graze around noxious species, leaving them to spread.
Manual control and spot-spraying suit isolated weed patches and areas too tight for machinery. Targeted herbicide application, rather than blanket spraying, reduces drift and off-target damage, particularly near drainage lines. Utilities generally rely on herbicides where total vegetation control is required, but industry guidance treats chemical control as one tool within an integrated program rather than the default first move, per EPRI’s best management practices for utility vegetation management.
Gravel and hard surfacing work well in high-security compounds or substation pads where zero vegetation is the goal, but they create drainage problems, raise local surface temperatures, and cost more to install and maintain than most operators expect.
Mixed strategies tend to outperform any single method. Strip-mowing the access lanes while leaving refugia strips between rows for pollinators gives you clear equipment paths without stripping every hectare of habitat value.
- Mowing: best for open, accessible sites with adequate array clearance
- Grazing (sheep): best for grazable pasture with reliable fencing and water
- Manual/spot-spray: best for isolated weed patches and tight corners
- Gravel: best for security-critical, zero-vegetation zones only
- Strip-mow with refugia: best all-round balance of access and biodiversity
Pro Tip: Walk your rows before locking in a method. A site that looks like open pasture on a drone survey can hide rock outcrops or wet patches that make grazing or mowing impractical in specific bays.
How should you plan and prepare the site before planting?
Getting the ground right before construction finishes saves years of remedial work. Extension guidance is blunt on this point: controlling existing vegetation and testing soil before seeding does more for long-term outcomes than any product you apply afterwards, according to Cornell Cooperative Extension’s guidance on permanent vegetation under solar arrays.
- Run a vegetation inventory and soil test first. This tells you what’s already in the weed seed bank, whether pH needs correction, and whether construction traffic has compacted the soil enough to need ripping before seeding.
- Control problem vegetation before you plant anything. Tillage, correctly timed approved herbicide application, or targeted physical removal all work, but skipping this step lets aggressive weeds establish alongside your seed mix and outcompete it within a season.
- Choose your seed mix based on the trade-off you’re willing to accept. Fast-establishing, low-growth species reduce erosion quickly and need less early intervention. Higher-diversity pollinator mixes take longer to establish and demand more attention in years one to three, but they pay that back in habitat value and, often, reduced long-term mowing.
- Set array height and row spacing with maintenance equipment in mind, not just yield. Low-clearance arrays around 45 centimetres can block standard mowers entirely, forcing you into manual trimming or specialised low-profile robotics for the life of the asset, a cost that extension research flags as a common and avoidable planning failure.
- Route cabling to keep access lanes clear. Buried or elevated runs that avoid crossing mowing paths save an enormous amount of operator time later.
If you’re assessing site access constraints before locking in equipment specifications, it helps to measure access requirements properly rather than guessing from a site plan.
What monitoring schedule and action thresholds actually work?
Vegetation management under arrays fails most often not because the wrong method was chosen, but because nobody checked on it often enough to catch problems early. An integrated framework, one that sets clear inventories, thresholds and monitoring intervals, keeps intervention proportionate and defensible, a principle laid out in the FHWA’s roadside revegetation guidance.
What to check on every site walk:
- Average plant height across representative rows, not just the tallest patches
- Percent ground cover and any bare soil expanding at drip-lines
- Presence of perennial or noxious species, especially before they flower
- Panel shading from encroaching growth, checked from a low sun angle
- Erosion channels forming beneath the lower edge of each row
Sensible action thresholds look like this: mow or graze when average grass height exceeds a moderate height, or immediately if a noxious species is approaching flower, since letting it set seed adds years of extra control cost. Twice-yearly inspection is a practical minimum in most Australian climates, tightened to quarterly during the establishment phase.
The first three to five years demand far more attention than steady state. Native and high-diversity mixes in particular carry front-loaded costs, more seeding, more spot-spraying, more mowing passes, before maintenance eases off, a pattern confirmed across a multi-site study of ground cover costs at utility-scale solar sites. Log every inspection, threshold trigger and intervention into your asset-management system so establishment-phase trends are visible, not anecdotal.
Safety, wildfire risk and regulatory obligations
Electrical clearances aren’t negotiable. Maintain manufacturer-specified distances between vegetation and live equipment, and keep anyone who isn’t trained in your site’s safe system of work well away from inverters and combiner boxes, a point worth reinforcing with anyone unfamiliar with how solar electrical systems are wired.
Fuel-load management matters as much as aesthetics. Strip-mowed fuel breaks around perimeters and between rows, timed ahead of fire season, reduce risk and should be coordinated with your local fire authority’s guidance for the season.
Herbicide use requires label compliance, defined buffer zones near waterways, and drift-reduction techniques such as low-pressure nozzles and wind-speed cutoffs. Keep records of every application. Bring in licensed contractors for chemical work, grazing management, or erosion remediation once a job exceeds your in-house expertise.
Balancing biodiversity with panel efficiency
Refugia strips between rows, left unmown while access lanes stay clear, give pollinators habitat without compromising the clearances that matter for equipment and shading. You don’t need to sacrifice one for the other; you need to decide which strips serve which purpose and hold that line consistently.
Drip-line erosion is one of the most overlooked long-term risks on solar sites. Runoff concentrates at the lower edge of every panel row, and left unaddressed it undermines footings over several seasons, a failure mode detailed in Penn State’s research on stormwater controls at solar farms. Buffer plantings and soil reinforcement at these points cost far less than remediation after the fact.
Diverse seed mixes also do quiet, practical work: a well-established native sward resists invasive colonisation better than a monoculture, which cuts your long-term spot-treatment load. Where you can, shift mowing timing across seasons rather than cutting on a fixed calendar date, avoiding peak flowering periods to protect pollinator value while still controlling seed set.
Pro Tip: Mark your refugia strips physically on-site, flags or painted stakes work fine, so contract mowing crews don’t accidentally cut habitat zones during a routine pass.
Where does automation fit into under-array maintenance?
Robotic mowers earn their keep on the sites where conventional equipment struggles most: tight row spacing, frequent repeat passes needed to stay ahead of growth, and labour shortages that make weekly manual mowing impractical. Autonomous units can run scheduled passes without an operator standing in a live electrical environment, which is itself a safety win.
They have limits worth planning around. Battery runtime constrains coverage per session, steep slopes reduce traction and safe operating range, and fine detail work around cabling or mounting hardware still needs a human or a targeted spot-spray pass. The strongest programs combine robotics for the bulk of row maintenance with grazing or manual control for edge cases.
- Best fit: tight access rows, high-frequency mowing needs, restricted labour availability
- Needs supplementing: steep terrain, dense noxious weed patches, cabling-adjacent trimming
- Safety consideration: autonomous units still require defined exclusion zones near electrical infrastructure and documented safe operating procedures
Robotics deliver the most value where safe, repeated close-proximity access is otherwise expensive or hazardous to achieve with a person on a machine.
Quick decision checklist for matching method to site
- Confirm access constraints and array geometry, row spacing, table height, and any low-clearance bays.
- Assess current weed pressure and soil condition to identify which areas need remediation before any method is chosen.
- Select a primary method (mowing, grazing, robotics, or a mixed approach) based on that access and weed profile.
- Run a pilot on a representative section with defined action thresholds before rolling out site-wide.
- Schedule monitoring at minimum twice yearly, tightened to quarterly during establishment.
For heavy noxious weed patches or active drip-line erosion, don’t wait for the next scheduled walk; flag it for immediate spot treatment or engineering intervention, since both problems compound quickly if left.
The practical future of low-impact under-array management
Balancing biodiversity with reliable operations isn’t a compromise, it’s the actual job. Sites that treat pollinator strips and erosion control as afterthoughts pay for it in remediation costs later. The sensible path to scaling better methods is through pilots on real sites, tested against your own access constraints and weed pressure, not blanket adoption of whatever worked somewhere else.
— BrightView
How BrightView can help manage vegetation beneath your arrays
A specialist provider offers asset managers and councils a way to run under-array maintenance without the safety exposure and scheduling headaches of sending crews through live electrical rows week after week. Robotic mowing, selective spot-spraying and robotic panel cleaning services are built for tight-access, repeat-pass conditions described above, where conventional equipment struggles and manual labour is hard to schedule reliably.
We start every engagement with a site assessment: access mapping, weed inventory, and a pilot area with defined action thresholds, the same process outlined earlier in this guide. From there, we scale into an ongoing maintenance program tailored to your establishment phase or steady-state needs. If your site combines vegetation control with panel efficiency concerns, our robotic lawn mowing service and automated grounds maintenance programs cover both in a single contract. Get in touch to arrange a site assessment and pilot on your access lanes before your next mowing cycle.
Sources
- Vegetation management cost and maintenance implications of different ground covers at utility-scale solar sites (Sustainability / MDPI)
- Planning and managing permanent vegetation under solar arrays (Cornell Cooperative Extension)
- Roadside revegetation: an integrated approach to establishing native plants and pollinator habitat (FHWA)
FAQ
How often should vegetation under solar arrays be inspected?
Twice yearly is a practical minimum in most Australian climates, increasing to quarterly during the first three to five years of establishment when growth is least predictable.
Are sheep better than goats for grazing under solar panels?
Yes. Sheep graze evenly at low height and rarely climb or chew on equipment, while goats are prone to both behaviours, which makes them a poor fit around panel structures and wiring.
Does native vegetation cost more than turf under arrays?
Establishment costs are typically higher for native, low-growth mixes in the first three to five years, though mowing frequency usually drops afterwards; sheep grazing costs have been found comparable to turfgrass on a per-site basis.
Can robotic mowers handle solar farm vegetation management?
Robotic mowers handle tight-access rows and frequent repeat passes well, though battery range, slope, and fine trimming near cabling still need supplementing with manual or grazing work; BrightView Solar & Groundskeeping designs pilot programs around exactly these limits.
What triggers action on vegetation under panels?
Common thresholds include mowing when average grass height exceeds a moderate height, or intervening immediately once a noxious species approaches flowering, since seed set adds years of extra control cost.
