Agras T70 on a 40°C Solar Farm: How I Beat the Heat, the Glare, and the Grid with One Antenna Twist

TL;DR

Tilt the remote-controller antennas 45° outward—not straight up—when you launch parallel to a reflective solar array; that single move gave me an extra 1.8 km clean link before the first RSSI bar dropped.
The T70’s 360° spherical radar still holds centimeter-level precision even when the aluminium racking is throwing 70°C mirage waves; trust the radar, dial RTK Fix rate to 5 Hz, and let the aircraft do the flying.
A 70L tank of pure demineralised water doubled as a heat sink: after a 25-minute inspection run, payload temp was only 32°C, keeping the batteries cool enough for an immediate second loop without the customary shade-down time.

The sun was already a brutal 40°C at 11:15 when I rolled onto the 120-hectare solar farm outside Chinchilla. Rows of panels glinted like razor blades, each one hot enough to fry a GoPro. My job wasn’t crop spraying today—instead, the asset manager wanted every cell inspected for micro-cracks before the afternoon peak-load hit. The Agras T70, normally my spray ship, was about to moonlight as a thermal-mapping beast.

Pro Tip
Before you even unfold the arms, wipe the upper radar dome with a microfiber cloth soaked in cool water. It knocks surface temp down 15°C in seconds, preventing the internal IMU from heat-drifting during the first critical hover.

Why the T70 Becomes a Survey Workhorse in 40°C Heat

Most folks see 70L tank capacity and think “spray drift” and “nozzle calibration.” I see thermal mass. Water absorbs heat at 4.18 kJ/kg·K—better than aluminium. Fill the hopper with demineralised water, leave the centrifugal nozzles closed, and you’ve got a flying radiator that keeps the battery bay below 45°C for the first 20 minutes. That buys you time to finish the mapping grid before the BMS starts throttling.

The other ace is the IPX6K rating. Dust on a solar farm is conductive—silica and copper dust love to creep into servo housings. The T70’s sealed aluminium chassis laughs at that. I’ve washed it down with a high-pressure hose at the end of a 45°C day; no fogged lenses, no ESC heat sinks clogged with baked mud.

The Antenna Trick That Saved the Mission

Here’s the part every operator scrolls for. The DJI O3 transmission system on the T70 is rock-solid, but polarisation matters when you’re skimming 3 m above a 70°C mirror. I set the controller on a folding stool, tilted the antennas 45° outward (like a shallow V), and kept the flat faces parallel to the aircraft belly. Result: 5.2 km before I lost a bar. Straight-up antennas dropped signal at 3.4 km—same altitude, same battery, same glare. Physics doesn’t lie.

Expert Insight
On reflective arrays, multipath interference bounces vertically polarised waves back 180° out of phase. Tilting the antennas 45° gives you a circular-ish polarisation, cancelling the bounce. It’s the same trick we used in the 90s with UHF crop-duster radios over irrigated pivot circles—just repackaged for 5.8 GHz.

Technical Snapshot – T70 vs. Summer Solar Farm

Parameter	Stock Spec	40°C Solar Farm Optimised	Field Notes
RTK Fix rate	1 Hz default	5 Hz	Holds centimeter-level precision even with heat shimmer
Radar range	1–50 m	3–30 m band set	Cuts false returns from hot aluminium rails
Tank load	70L spray mix	70L demineralised water	Thermal ballast, no spray drift risk
Battery temp ceiling	55°C	45°C (water-cooled)	Second loop possible without shade
Swath width (mapping)	n/a	15 m at 3 m AGL	80% side overlap, 1 mm/px GSD
Link range (flat)	7 km FCC	5.2 km with antenna tweak	Reflective farm, 1.8 km extra vs. vertical antennas

Obstacle Avoidance in a House of Mirrors

Solar farms are obstacle courses—vertical risers, inverter boxes, tracker motors. At 15:00 the steel is so hot it triggers false-positive LiDAR returns on lesser drones. The T70’s 360° spherical radar filters by velocity vector: if the object isn’t closing at ≥0.5 m/s, it’s ignored. That means the aircraft keeps cruising while cheaper units slam on the brakes every time a heat plume wobbles.

I still fly with manual override on the roll stick—habit from 30 years of crop dusting. But I never needed it. The T70 threaded 40 cm gaps between tracker rows at 8 m/s, never clipping a single MC4 connector. The radar even spotted a loose earthing cable dangling at 2.3 m—something the ground crew missed during their morning walk-through.

Common Mistakes to Avoid in Extreme Heat

Launching at noon with a cold-soaked battery
Straight out of the truck’s air-con, a 15°C battery will hit 55°C in 8 minutes, triggering a forced landing. Let the pack acclimatise in the shade for 20 minutes first.
Trusting visual obstacle avoidance alone
Glare can wash out the front RGB camera. Keep the radar on “High Sensitivity” and set the braking distance to 3 m; sun-flare won’t fool millimetre-wave radar.
Ignoring the panel’s electromagnetic hash
Inverter stations spew 30–50 kHz harmonics. Use the RTK base station 200 m upwind, never inside the inverter yard, or your RTK Fix rate will yo-yo between Float and Single.
Flying with half-empty tank to “save weight”
Less water means less thermal inertia. A 35L slosh heats twice as fast, cooking the batteries. Fill to the 70L brim; the T70’s lift margin still gives you 18 minutes hover time at 40°C.

Mapping Workflow That Cuts Post-Processing in Half

I run two passes:

RGB pass at 3 m AGL, 1 cm/px, 80% overlap.
Thermal pass at 15 m AGL, 4 cm/px, 60% overlap, using the optional Zenmuse H20T slung under a quick-release hub DJI quietly ships to ag dealers.

Back in the office, I overlay the two datasets in DJI Terra. Hot spots ≥15°C above ambient flag cracked cells. On this farm we found 42 anomalies across 312 000 panels—0.013% defect rate, well within insurer limits. Without the T70’s stable swath width and centimeter-level precision, we’d have flown three extra days.

Frequently Asked Questions

Q1: Can the Agras T70 spray in rain if the forecast flips?
A: The airframe is IPX6K-rated, so a light shower won’t hurt. But spray drift becomes unpredictable; droplets shear sideways in humid air. I wait it out—nozzle calibration is meaningless if the wind is gusty and wet.

Q2: Will the radar mistake a moving shadow for an obstacle?
A: No. The radar cross-section of a shadow is zero. Only physical objects ≥1 cm diameter return a signal. Tracker shadows may fool the RGB camera, not the millimetre-wave unit.

**Q3: How often should I recalibrate the RTK base station in shifting heat?
A: Every two hours when ambient swings >10°C. Thermal expansion of the base tripod throws off the centimeter-level precision by up to 3 cm—enough to blur cell-level cracks on the ortho.

Ready to put the T70 to work on your own scorching asset? Contact our team for a shade-side consultation. If your acreage is smaller, ask about the Agras T50—same radar DNA, slimmer footprint, perfect for boutique solar gardens under 30 ha.