Manufacturing feasibility assessment
5. Verdict
Viable in India, but replace direct nutrient sensing with calibrated EC/pH proxies and validate the 5-year power budget; start with 50 field pilots and one LoRa gateway.
6. Subsystems
- 6.1 Soil sensing spikeHIGH
- 6.2 Power systemMEDIUM
- 6.3 LoRa communicationsMEDIUM
- 6.4 Weatherproof enclosureMEDIUM
- 6.5 Gateway and farmer workflowMEDIUM
- 6.6 Calibration and agronomy modelHIGH
7. Bill of materials
| Item | 100 | 1,000 | 10,000 |
|---|---|---|---|
| 7.1 LoRa MCU/radio module, antenna and RF passives | ₹520–₹680 | ₹340–₹460 | ₹240–₹330 |
| 7.2 Capacitive moisture, EC and temperature probe assembly | ₹850–₹1,150 | ₹560–₹780 | ₹390–₹560 |
| 7.3 Replaceable pH/nitrate sensing cartridge and interface | ₹900–₹1,400 | ₹620–₹980 | ₹450–₹720 |
| 7.4 Solar cell, Li-SOCl2 reserve battery, PMIC and protection | ₹620–₹850 | ₹430–₹610 | ₹310–₹470 |
| 7.5 IP67 UV-stable enclosure, probe body, seals and cable gland | ₹460–₹650 | ₹280–₹420 | ₹180–₹290 |
| 7.6 PCB, assembly, potting, final test and calibration | ₹650–₹900 | ₹420–₹610 | ₹290–₹430 |
| 7.7 Total delivered BOM and conversion, excluding GST, gateway and dealer margin | ₹4,000–₹5,630 | ₹2,650–₹3,860 | ₹1,860–₹2,800 |
At 10,000 units, tooling adds ₹120–₹220 per unit, or 2.7–4.9% of ₹4,500 retail. At 1,000 units it adds ₹1,200–₹2,200 per unit; use machined/soft tools until field validation.
8. Gates to clear
8.1 [DFM]
A buried spike combines moisture ingress, cable fatigue and nutrient-electrode replacement; a sealed disposable design will fail service economics.
Path: Build a two-piece glass-filled nylon probe with overmoulded cable, O-ring service cap and replaceable sensor cartridge; run 20-unit thermal-cycle, soak and insertion-cycle trials at an Indian environmental test lab.
8.2 [Certification]
The 865–867 MHz LoRa transmitter requires Indian radio approval, and the lithium battery pack needs transport and safety evidence.
Path: Use a WPC ETA-approved LoRa module or obtain WPC ETA through an Indian RF compliance lab; qualify the cell/pack to IEC 62133-2 or applicable IS 16046 evidence and obtain UN 38.3 transport documentation from the battery vendor.
8.3 [Tooling]
At ₹4,500 retail, direct multi-ion nutrient sensing and full hard tooling leave little room for dealer margin, warranty and gateway support.
Path: Launch moisture, EC and temperature as the standard unit; offer nutrient cartridges as an annual paid service after district calibration, use soft tooling for the first 1,000 units, then release hard tools after 70%+ field-retention validation.
9. Prototype sequence
- 9.1Define the first release as moisture, EC, temperature and LoRa telemetry; specify nutrient sensing as a replaceable, validated option.This preserves useful irrigation value while avoiding unsupported NPK accuracy claims.
- 9.2Build 20–30 instrumented prototypes using off-the-shelf WPC ETA-capable LoRa modules, solar harvester boards and machined IP-rated housings.This verifies RF range, energy budget, ingress protection and installation method before tooling.
- 9.3Run a 90-day field pilot across two soil types and crops with paired gravimetric moisture readings and laboratory nutrient samples.This creates the calibration dataset needed to quantify sensor accuracy and cartridge drift.
- 9.4Complete gateway link-budget survey, battery seasonal simulation and accelerated soak, UV, insertion and cable-pull tests.These tests expose the main five-year reliability risks before design freeze.
- 9.5Freeze the serviceable probe architecture, complete WPC ETA and battery documentation, then commission soft tooling for a 500–1,000 unit pilot.This limits capital exposure while establishing a manufacturable, compliant dealer trial product.
Inspector: J. Tanikella
Assessment criteria: J. Tanikella (T-Works, YC). Engine: GPT-5.6 Terra.