Looking at the clock and starting the dishwasher when the ring is green is the first step. The second is to stop looking. EcoWatch can switch Shelly smart plugs and relays directly over your home Wi-Fi, following the same colours you see on the dial. Once a rule is set, a towel radiator, a water heater, an engine heater or an EV charger follows the price every quarter hour without anyone touching anything. No Shelly cloud account, no app, no hub.
What you need
- An EcoWatch (any model) connected to your Wi-Fi.
- One or more Shelly devices on the same network. Supported: Shelly Plug S, Plug M Gen3, Plus 1, Plus 1PM, Plus 2PM, Plus Plug, Plus Uni, Mini 1, Mini 1PM, the Pro series, the Gen3 and Gen4 models, and the older Gen1 devices (Shelly 1, 1PM, 2.5, Plug, Plug S, EM). Anything with a relay works; a plug is the simplest start.
- Five minutes.
Step 1: connect the Shelly to your Wi-Fi
Use the Shelly app or the device's own setup page, as with any Shelly. It only needs to be on the same network as the clock; it does not need a cloud account.
Step 2: find it from the clock
Open http://ecowatch.local in a browser on the same network, choose Devices, then Add device, then Search for devices. The clock scans the network and lists every Shelly and HomeWizard P1 it finds. Click the one you want to add it. You can rename it, so "ShellyPlus1-CC7B…" becomes "Water heater" (in the screenshots below, in Swedish: "Pannan extra varmvatten").
Step 3: set the rule
Each relay on the device gets its own rule. The options are:
- On during low (green hours). The default, and the right choice for most loads.
- On during medium (yellow) and On during high (red). Tick these too if the load must run anyway and you only want to avoid the worst hours, or leave only low ticked for strict savings.
- Always off during tariff. If your grid company has a time-based tariff and you have set those hours on the clock, the relay stays off during them regardless of price.
- On below cost. Enter a price in öre or cents; the relay is on whenever the price is below it. Useful for a water heater: "heat whenever electricity is under 50 öre".
- Energy mode (P1 meter). If you have a HomeWizard P1 meter connected, switch on when the house draws less than X watts and off when it draws more than Y. This is how you keep the car charger from running while the sauna is on.
Save. The device page shows the status of each relay in plain words: "On due to low price", "Off due to tariff", "On due to cost threshold".
Step 4: let it run
EcoWatch re-evaluates every quarter hour when the price changes and sends the on or off command to the Shelly over the local network. If the Shelly stops answering, the clock can blink orange at the side so you notice (tick "Blink on bad status" on the Devices page).
What to put on a plug
- A hot-water heater is the best candidate in most houses: it stores heat, so running it in the six cheapest hours costs nothing in comfort.
- Towel radiators, floor heating in a bathroom, an engine or cabin heater on a timer.
- EV charging through a Shelly-controlled wallbox, or a granny charger on a Plug M (check the current rating; Plug M Gen3 handles up to 3 000 W).
- A dehumidifier in the basement, a pool pump, an aquarium heater.
- Not: a freezer or anything that must not be interrupted.
Manual override
Press the button on the Shelly or use its own page to switch it; EcoWatch leaves it alone until the next price change, then applies the rule again.
Buying the plugs
We sell the Shelly Plug M Gen3 as a 2-pack because that is the model we test every firmware against. Any supported Shelly from any shop works the same way. If you also want the price in your smart home, see EcoWatch in Home Assistant.