Buying guide
What to actually order, and from where
A practical bill of materials for each common configuration. Prices are 2026-05 EU retail; multiply by 1.05 for cantons that add a recycling levy. Vendor links are not affiliate links — pick the local distributor that gets to you fastest.
Single fridge — minimum HACCP
| Item | Qty | Unit price | Notes |
|---|---|---|---|
| Shelly H&T Gen3 | 1 | €30 | WiFi + battery, recommended starting point |
| Velcro adhesive strips | 1 | €4 | For non-conducting mount |
| Spare 18650 cell + charger | 1 | €18 | For year 2 |
Total: ~€52 + €348 (annual SaaS). Payback per the ROI page: 3.3 months.
Buy from: shelly.com direct, Amazon EU, Reichelt, Conrad. Avoid the "Smart H&T" listings on Aliexpress (counterfeits).
Walk-in fridge + freezer (small café)
| Item | Qty | Unit price | Notes |
|---|---|---|---|
| Shelly H&T Gen3 | 2 | €30 | One for walk-in, one for reach-in |
| Shelly H&T Plus (USB-powered) | 1 | €38 | For freezer — USB power avoids battery freeze |
| Velcro strips | 1 | €4 | |
| USB-C 1 m cable + 5 V brick | 1 | €10 | For the USB-powered Shelly |
Total: ~€110.
The freezer sensor is USB-powered because lithium batteries lose capacity dramatically below −20 °C. A battery Shelly works in a freezer for a season; then the battery dies prematurely. Drop the USB cable through the door gasket or use the built-in cable port.
Small hotel (Legionella)
| Item | Qty | Unit price | Notes |
|---|---|---|---|
| Efento NS-T-3 LoRaWAN | 4 | €95 | Cylinder top/bottom, supply, return |
| Efento NS-T-3 external probe | 2 | €30 each | Pipe contact mounting |
| Mikrotik wAP LR8 EU868 | 1 | €180 | TTN gateway |
| Pipe thermal paste | 1 | €12 | For contact probes |
| Pipe insulation 30 cm × 4 | 1 | €15 | Over the contact probes |
Total: ~€590 first year, ≈€348 / year SaaS.
Set the LoRaWAN cadence to 5 minutes at install; reduce to 15 minutes after verifying coverage.
Server room (single rack)
| Item | Qty | Unit price | Notes |
|---|---|---|---|
| Shelly H&T Gen3 | 2 | €30 | Intake + exhaust |
| Shelly Flood Gen3 | 1 | €25 | Under the rack |
| Shelly Door / Window Gen3 | 1 | €20 | (Optional) Door sensor |
| USB-C bricks for sensors | 3 | €8 | All USB-powered for reliability |
Total: ~€135.
For an open-frame rack in a basement closet, swap the H&T sensors for Efento NS-T LoRaWAN if WiFi is unreliable.
DIY ESP32 + BME280
| Item | Qty | Unit price | Notes |
|---|---|---|---|
| ESP32-WROOM-32 dev board | 1 | €4 | Aliexpress / Reichelt |
| BME280 I²C breakout | 1 | €2 | Confirm BME280, not BMP280 |
| Jumper wires (40-pack) | 1 | €2 | One-time cost |
| 18650 holder + cell | 1 | €4 | For battery operation |
| USB-C cable + 5 V brick | 1 | €6 | For mains operation |
| Acrylic project box | 1 | €5 | Ventilation holes mandatory |
Total: ~€23 per node.
For a school or museum installing 8+ identical sensors, DIY is substantially cheaper than commercial. The trade-off is that you are the maintainer.
Climate (school, single classroom)
| Item | Qty | Unit price | Notes |
|---|---|---|---|
| ESP32-S3 + Sensirion SCD41 | 1 | €55 | NDIR CO₂ + T + RH |
| Acrylic box with holes | 1 | €6 | Vented, no direct airflow |
| USB-C cable + 5 V brick | 1 | €6 | Mains-powered |
| Wall mount adhesive | 1 | €3 | At breathing height (1.5 m) |
Total: ~€70 per classroom.
Alternative: Aranet4 Home (€220) — battery, e-paper display, BLE. Useful when you want a wall-mounted "traffic light" the classroom can see at a glance. OpenSense integrates via a BLE-to-WiFi gateway (separate device, ≈€35) or via a phone-side relay.
Energy (single workshop)
| Item | Qty | Unit price | Notes |
|---|---|---|---|
| Shelly Pro 3EM (DIN rail) | 1 | €140 | Three-phase, full panel |
| 50 A CT clamps (×3) | included | — | In the box |
| DIN-rail real estate (≥ 4 modules) | 1 | install cost | Get an electrician for the panel |
Total: ~€140 + electrician fee.
For a single-phase or single-appliance circuit, the Shelly Plug S Gen3 (€20, plug-through) replaces the panel install entirely. Limited to 3.6 kW circuits.
Calibration kit (any vertical)
For operators who care about traceability — see calibration:
| Item | Qty | Unit price |
|---|---|---|
| Fluke 1551A Stik thermometer | 1 | €700 |
| ISO 17025 cert (annual) | 1 | €120 / yr |
| Insulated ice-bath flask | 1 | €25 |
| Two-point calibration spreadsheet | — | free (template on request) |
Optional unless you are pharmacy-grade.
Where to buy
EU vendors that ship to small businesses without hassle:
- shelly.com — direct, fast EU shipping.
- Reichelt (DE) — wide selection, includes Efento, ESP32, BME280.
- Conrad (DE/AT/CH/CZ/SK) — slightly pricier but local depots in most EU capitals.
- Distrelec (CH/AT/DE) — for industrial-grade Efento and PT100.
- Amazon EU — fast for Shelly, careful with the no-name listings.
For Slovak buyers specifically:
- TIPA.eu — Slovak distributor with quick Bratislava delivery.
- Hadex.cz — Czech, ships SK same week.
We will ship a small starter kit (3 × Shelly H&T + USB bricks + a QR-coded onboarding card) to Slovak pilot customers at cost. Email us before the first month if you want one.