Greenhouse Controller Starter Stack
A complete component list for building a Raspberry Pi-based greenhouse climate controller with sensor nodes and relay outputs.
Overview
This product stack covers the core components needed to build a basic but functional greenhouse climate controller. The system uses a Raspberry Pi as the central gateway, Teensy 4.1 microcontrollers as sensor/actuator nodes, and MQTT for communication.
This is the same hardware stack used in our 30x96 high tunnel automation build. Every component listed has been field-tested.
Gateway
| Component | Model | Approx. Cost | Notes |
|---|---|---|---|
| Single-board computer | Raspberry Pi 5 (4GB) | $60 | 8GB is overkill for this application |
| Case | Argon ONE V3 | $25 | Good thermal management, GPIO access |
| Power supply | Official RPi 27W USB-C | $12 | Do not cheap out on PSU — brownouts cause SD corruption |
| Storage | Samsung EVO Plus 64GB microSD | $12 | A2 rated for better random I/O |
| USB WiFi adapter | Alfa AWUS036ACM | $30 | Only needed if built-in WiFi has range issues |
Sensor Nodes
| Component | Model | Approx. Cost | Notes |
|---|---|---|---|
| Microcontroller | Teensy 4.1 | $32 | Excellent I/O, real-time capable, Arduino ecosystem |
| Ethernet module | Teensy 4.1 Ethernet Kit | $5 | Hardwired preferred over WiFi for reliability |
| Temp/humidity sensor | SHT31 breakout | $8 | I2C, ±0.3°C accuracy, reliable in humid environments |
| Radiation shield | 3D-printed Stevenson screen | $3 | Required for accurate greenhouse temperature readings |
| Enclosure | IP65 junction box (150x110x70mm) | $8 | Size for your specific node configuration |
| Power | Mean Well HDR-15-5 DIN rail PSU | $12 | 5V/2.4A, reliable for 24/7 operation |
Actuator Control
| Component | Model | Approx. Cost | Notes |
|---|---|---|---|
| Relay board | SainSmart 8-channel with opto-isolation | $18 | 5V logic, rated for 10A/250VAC per channel |
| Solenoid valve | U.S. Solid 3/4” 12V normally closed | $15 | Brass body, rated for water, needs external 12V PSU |
| Contactor | Packard C240B 2-pole 40A | $20 | For switching fan motors — do not switch motors directly with relays |
| Wiring | 18 AWG stranded THHN (multi-color) | $25/roll | Use different colors for signal, power, and ground |
| Terminal blocks | DIN rail terminal blocks (20-pack) | $15 | Spring-cage type for tool-free wiring |
Communication
| Component | Model | Approx. Cost | Notes |
|---|---|---|---|
| Network switch | TP-Link TL-SG105 5-port gigabit | $18 | Unmanaged, reliable, low power |
| Ethernet cable | Cat6 outdoor-rated (100ft) | $20 | UV-resistant jacket for greenhouse runs |
| MQTT broker | Mosquitto (software) | Free | Runs on the Pi alongside the control service |
Total Estimated Cost
$350–450 depending on number of nodes, cable runs, and enclosure choices. This does not include fans, motors, or other large equipment — those are site-specific.
Trade-Offs
- Teensy vs. ESP32: Teensy is more expensive but offers better I/O performance and deterministic timing. ESP32 is cheaper and has built-in WiFi, but WiFi reliability in electrically noisy greenhouse environments is a real concern. We use Teensy with Ethernet for production systems.
- microSD vs. SSD: An NVMe SSD via USB adapter eliminates SD card corruption risk but adds $40–60. Worth it for systems that log heavily.
- DIN rail vs. free-form: DIN rail mounting adds upfront cost but dramatically improves serviceability. Worth it for any permanent installation.
Procurement Notes
- Buy Teensy directly from PJRC — counterfeit boards exist on Amazon
- SHT31 breakouts from Adafruit are consistently good quality; generic boards often have poor soldering
- For solenoid valves, verify the voltage and normally-open/normally-closed configuration before ordering — returns on hydraulic components are painful