70 L of Trust: How the DJI Agras T70P Keeps RTK Lock While Spraying Solar Arrays in Post-Rain Mud
70 L of Trust: How the DJI Agras T70P Keeps RTK Lock While Spraying Solar Arrays in Post-Rain Mud
TL;DR
- Signal stability is the only way to hold centimeter-level precision when metal panel rows and water-logged soil create EMI and wheel-sucking mud.
- The T70P’s Active Phased Array Radar, Dual Atomization nozzles, and IPX6K rating let you finish a full 70 L tank in a single pass—even when traction is zero and spray drift is high.
- Correct nozzle calibration and a >95 % RTK Fix rate cut chemical use by 12 % and eliminate manual re-sprays on steep solar berms.
05:45 – Mud, Metal, and the Memory of a Failed Mission
Last spring we tried to treat a 22 ha solar farm with a 40 L-class rotorcraft after a night shower. Steel stanchions, inverter boxes, and saturated loam turned the field into an RF hall of mirrors. RTK dropped to Float, then Single; the old bird wandered 30 cm off-track, coating the aluminium rails with copper fungicide. Manual clean-up cost the EPC contractor four man-days and a penalty clause.
This morning the same client called: humidity 92 %, soil moisture 38 %, forecast gusts to 8 m s⁻¹. We load the Agras T70P and leave the pickup tyres on firm grass—no need to drive into the plot thanks to the 70 kg spray payload and 15–20 min hover time.
06:10 – Pre-flight: Nozzle Calibration & Swath Width Math
We select TI-A4 stainless dual-atomization discs, 0.8 mm core, 60 ° fan. Target droplet VMD 180 µm to minimise spray drift over 3 m panel height. With boom at 1.8 m AGL, wind tunnel charts give a swath width of 7.5 m—perfect for the 7.2 m row spacing. One pass covers the aisle plus half-panel overlap; no double-coverage, no wasted AI.
Pro Tip: Calibrate at 10 % above field pressure (we run 2.2 bar instead of 2.0). When the pump compensates for viscosity changes in cold fungicide, droplet size stays inside the drift-mitigation window and RTK Fix rate remains rock-solid—no power sag from sudden PWM jumps.
06:30 – Signal Check: RTK Base, Array Radar, and EMI Map
We deploy the D-RTK 2 Mobile Station on a 1.5 m carbon tripod 450 m south of the array, clear of inverter cabins. Base logs Fix in 8 s; T70P shows 99 % Fix rate on controller HUD. We then toggle the Active Phased Array Radar: the unit sweeps a 120 ° frontal cone, mapping every panel edge as a 3-D polyline. Because radar bandwidth is 77 GHz, it ignores the 2.4 GHz Wi-Fi mesh the site operator uses—no spectral collision, no drop-outs.
06:45 – Take-off: Mud Below, Metal Above, Signal Locked
Pilot arms the motors; DB1560 Intelligent Flight Battery voltage 63.2 V, 98 % SOC. Aircraft weight 49.8 kg without load—still 30 kg under max AUW. We engage A-B line at 3 m s⁻¹; boom pressure stabilises in 1.2 s. Radar feeds real-time altitude to the flight controller, keeping 1.8 m above panel glass—no barometric drift even when temperature inverts at sunrise.
07:05 – Mid-mission: Spray Drift vs. Droplet Physics
A gust spikes to 7 m s⁻¹; spray drift plume tilts 15 ° leeward. Dual-atomization discs shear the mixture into 150–200 µm spheres; drift distance stays under 50 cm, well inside the 1 m concrete footpath. Meanwhile, Binocular Vision cameras detect a missing panel frame—aircraft yaw-commands 2 ° starboard, keeps centimeter-level precision without leaving the planned swath.
07:25 – Tank Empty, Data Full
70 L emptied in 14 min 06 s, 6.5 ha covered, average flow 4.97 L min⁻¹. RTK logged 99.2 % Fix; only 3 epochs entered Float for 0.4 s total. Radar recorded 112 obstacle updates—every stanchion, every inverter box. Agras SmartFarm Cloud auto-generates a multispectral mapping report by overlaying NDVI from last week’s Mavic 3 Multispectral flight—panels show 12 % less algae regrowth compared with hand-sprayed sector.
Post-mission Rinse: IPX6K in Action
We douse the aircraft with 150 L of clean water straight from the fire-fighting tank. IPX6K rating means 100 bar water jet from 15 cm—perfect for chemical flush. Battery bay gaskets stay dry; fan motors spin freely. Turn-around time: 6 min.
Technical Snapshot – Solar-Panel Spraying, Muddy Conditions
| Parameter | Agras T70P Field Value | Industry Benchmark |
|---|---|---|
| Tank capacity | 70 L | 40–50 L |
| Max payload (spray) | 70 kg | 40 kg |
| RTK Fix rate | ≥ 99 % | 92–95 % |
| Swath width (2.2 bar, 1.8 m AGL) | 7.5 m | 5–6 m |
| Droplet VMD (TI-A4) | 180 µm | 220–250 µm |
| Ingress rating | IPX6K | IPX4–5 |
| Obstacle sensing | Front & rear phased array + binocular | Front camera only |
| Battery hot-swap time | < 15 s | 45–60 s |
What to Avoid – Common Pitfalls on Solar Farms
Skipping base-station validation
Never trust network RTK inside an EMI canyon. Always plant a local base ≥ 200 m from inverters and verify Fix rate > 98 % before the first drop.Flying panel height instead of boom height
Pilots often lock radar to the glass surface; set offset to keep boom 1.8 m above glass, not skid height. One metre error doubles spray drift and violates label buffer.Ignoring nozzle wear after abrasive copper
Copper oxychloride eats TI-A4 cores within 80 tank-hours. Replace discs every 75 h or droplet size balloons, killing efficacy and breaching local drift regulations.Underestimating soil bearing
A 2.5 t pickup will sink 10 cm in 38 % moisture clay. Use the T70P’s 70 L capacity to finish the farthest rows first; battery swaps happen on firm grass, no site tow truck needed.
Expert Insight
Expert Insight: “Solar farms are the new vineyards—tight corridors, metal everywhere, and zero tolerance for stains. We run the T70P in Manual-Plus mode: radar holds height, RTK holds line, but the pilot can yaw 5 ° mid-swath to match tracker angle. Net result: 15 % less AI, zero rail clean-up, and the EPC keeps their performance bond.”
— Alex R., Chief Pilot, The Ag Service Provider, 1,800 ha solar treated since 2021
Frequently Asked Questions
Q1: Can the Agras T70P spray in light rain?
Yes. The IPX6K rating protects against powerful water jets; light rain (<5 mm h⁻¹) does not harm electronics. Maintain ≤ 3 m s⁻¹ forward speed to compensate for increased spray drift and keep droplet spectrum on target.
Q2: How often should I calibrate the Active Phased Array Radar?
Factory calibration is valid for 12 months, but run the built-in self-test every 50 flight hours. If the radar misses a 5 cm steel rod at 10 m, re-calibrate immediately to guarantee centimeter-level precision.
Q3: Is the T70P overkill for smaller solar sites (< 5 ha)?
For < 5 ha with flat terrain, the Agras T50 offers 40 L capacity and faster fold-up. On steep slopes or when post-rain mud blocks vehicle access, the T70P’s 70 kg payload and heavy-lift props still cut job time by 30 %—often justifying the larger airframe.
Ready to eliminate re-sprays and keep your solar asset spotless?
Contact our team for a site-specific workflow and see how centimeter-level precision beats manpower every time.