Evapotranspiration Calculator
Build an Evapotranspiration Calculator with Arduino Mega — Penman-Monteith Precision for Crop Water Needs
Every part needed, pre-tested for compatibility, with an AI build companion trained on this exact project. Shipped from Bengaluru in 3-5 days.
Turn four environmental variables — temperature, humidity, wind speed, and solar radiation — into the exact daily water requirement of any crop. This kit is built for engineers and researchers who need a hands-on tool to implement the FAO-56 Penman-Monteith equation on an Arduino Mega, transforming raw sensor data into actionable irrigation schedules. Whether it’s a Smart India Hackathon challenge on water scarcity or a B.Tech final-year project on precision farming, you’ll leave with a field-ready prototype that computes evapotranspiration in mm/day.
What You'll Build
You will assemble a portable, battery-powered instrument that reads temperature/humidity (DHT22), light intensity (BH1750), and wind speed via a Hall-effect sensor, then processes them through the Penman-Monteith algorithm. The 1.8-inch TFT displays real-time ET0 values, and every reading gets timestamped with a DS3231 RTC and written to MicroSD — creating a field log usable for irrigation scheduling of crops like wheat, rice, or maize.
What You'll Learn
- Implement the full Penman-Monteith equation in Arduino C++ using variables for net radiation, vapour pressure deficit, and aerodynamic resistance
- Interface multiple I2C and digital sensors (DHT22, BH1750, Hall-effect anemometer) without bus conflicts
- Design a robust data logging system with RTC timestamping and CSV storage on MicroSD for later analysis in Excel or Python
- Calibrate a DIY anemometer using pulse counting and convert it to wind speed at 2 m height per FAO standards
Kit Contents
| Component | Quantity |
|---|---|
| Arduino Mega 2560 | 1 |
| DHT22 | 1 |
| BH1750 | 1 |
| A3144 Hall Sensor | 1 |
| 1.8in TFT ST7735 | 1 |
| DS3231 RTC | 1 |
| MicroSD Module | 1 |
| 10kΩ Resistors | 10 |
| 100nF Caps | 10 |
| PCB Prototype Board | 2 |
| M-M Wires | 30 |
| 9V Battery Snap | 1 |
Why Buy This Kit Instead of Sourcing Parts Separately
| Factor | Sourcing Separately | Compoden Kit |
|---|---|---|
| Compatibility checks | You verify every part | Pre-tested as a system |
| Build support | Forums and scattered tutorials | AI companion trained on this exact project |
| Time to first working build | Days of debugging | Hours, with step-by-step guidance |
| Shipping coordination | Multiple sellers, multiple delays | One shipment from Bengaluru in 3-5 days |
Who This Kit Is For
This kit is built for B.Tech Agricultural Engineering, ECE, and EEE students developing precision irrigation prototypes at IITs, NITs, VIT, or state agricultural universities. Smart India Hackathon teams tackling water management themes will find every sensor needed for an evapotranspiration monitoring station. Final-year researchers and hobbyist agri-tech innovators get a semester’s worth of embedded systems learning with a real-world environmental monitoring outcome.
Built and Backed by Compoden
Every Compoden kit ships with an AI build companion trained on this exact project — accessible via a QR code on the box, with WhatsApp and email backup. We've spent 10 years building projects for makers, schools, and institutions across India. If a part fails because of a manufacturing defect, replace it free within 7 days.
What if I get stuck during the build?
Scan the QR code to access the AI companion trained on this exact kit’s wiring diagram, code, and calibration steps. If you need a human touch, message us on WhatsApp for troubleshooting support within 24 hours.
How do I measure wind speed with the included Hall sensor?
The A3144 detects magnetic pulses from a rotating anemometer (cup assembly not included). The AI companion provides a reference design using scrap materials and walks you through pulse counting, RPM-to-wind speed conversion at standard 2 m height, and calibration against a handheld anemometer.
Can this kit compute crop-specific water needs, or only reference ET?
The Penman-Monteith equation gives reference evapotranspiration (ET0). To get crop ET, you multiply by a crop coefficient (Kc). The companion explains Kc stages for Indian crops like rice, wheat, sugarcane, and cotton, and you can input Kc directly in the code.
Is this suitable for long-term outdoor deployment?
With a 9V battery and MicroSD logging, the unit can run unattended for days. For permanent field use, you’ll need to weatherproof the enclosure (not included) and consider a solar-powered supply. The code is structured to handle sensor failures gracefully and resume logging upon power cycles.
Temperature, humidity, wind speed and solar radiation inputs feed a Penman-Monteith equation to compute daily crop water need.
What's in this kit
Choose your assembly option:
- Soldering Kit — 25W soldering iron, 60/40 solder wire, flux, and small perfboard for permanent assembly.
- Breadboard Combo — 800-point full-size breadboard with 65-piece jumper wire pack for solderless prototyping.
Shipping Information
- Prepaid Orders: ₹75 for orders up to ₹999, FREE shipping above ₹999
- COD Orders: ₹125 shipping + ₹50 COD fee = ₹175 total
- Delivery Timeline: Dispatch in 1-2 days, delivery in 2-7 days depending on location
Returns & Warranty
- 7-Day Return: Manufacturing defects only (approval required)
- Warranty: 7 days from delivery
- Non-Returnable: Batteries, consumables, cut wires, clearance items