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One Shelly, three parts, about 10 minutes. This guide takes you from zero to first savings — starting tomorrow.

Check these before you start

  • Email access: you need it to register your Optimaatti account.
  • Shelly device installed: device is in place and powered on. For models that require electrical wiring, always use a qualified electrician.
  • Shelly app on your phone: download it from the App Store or Google Play. You need it to connect the device to Wi-Fi.
  • Your home Wi-Fi password: your phone is on the same network that Shelly will use.

Start with one device — a water heater or an electric heater works best. Savings begin fastest from these. Once the first one works, adding more is quick.

Electrical safety

If installing Shelly requires electrical wiring, always use a qualified electrician. Plug-in models you can install yourself.

Part 1 / 3 · ~2 min

Optimaatti account

Create an account and get your own connection details.

  1. 1

    Register

    Optimaatti

    Create a free account to get your own connection details.

    • Open `https://app.optimaatti.fi` on your phone or computer.
    • Tap `Register` and enter your email and a password.
    • Verify your email by clicking the link sent to you.
    • Sign in.

    Keep the browser open — you will continue from the same place in step 2.

  2. 2

    Copy the connection details

    Optimaatti

    Four values tell Shelly how to find Optimaatti.

    • Open the `Connection details` page from the menu.
    • You will see four fields: server address, port, username and password.
    • Copy them or keep the page open in another tab.
    • Use the values exactly as shown.
    Optimaatti Connection details page
    The Connection details page shows the server, port, username and password all in one view.

    Check these in the screenshot:

    1. 11. Open the `Connection details` page from the menu.
    2. 22. You will see four fields: server address, port, username and password.
    3. 33. Copy them or keep the page open in another tab.

    The password is shown only on this page. Copy it now — you can always regenerate a new one later if it gets lost.

    Advanced: what these values are
    They are MQTT connection credentials. Multiple Shellys can share the same credentials — a device-specific client id separates them automatically. Port 8883 uses TLS encryption (recommended), 1883 is an unencrypted connection.
Part 2 / 3 · ~5 min

Connect Shelly

First to Wi-Fi, then to Optimaatti.

  1. 3

    Shelly to your Wi-Fi

    Shelly app

    Shelly needs to be on the same Wi-Fi network as your phone.

    • Power on the Shelly device.
    • Open the Shelly app and sign in or register.
    • Tap `Add Device` and follow the guided setup.
    • Pick your home Wi-Fi and enter the password.
    • Wait for the device to appear in the Shelly app device list.

    The Shelly app is a different app from Optimaatti — it is made by the device manufacturer. You only use it for the Wi-Fi step; everything else happens in Optimaatti.

  2. 4

    Link to Optimaatti

    Shelly app

    Enter the connection details into Shelly so it starts talking to Optimaatti.

    • In the Shelly app, open the device settings.
    • Find the `MQTT` section and turn it on.
    • Enter the values you copied in step 2: server, port, username and password.
    • Check there are no extra spaces in any field.
    • Save. Shelly will connect to Optimaatti within seconds.
    Shelly device connection settings
    Copy the connection details from Optimaatti to your Shelly settings. Use them exactly as shown.

    Check these in the screenshot:

    1. 11. In the Shelly app, open the device settings.
    2. 22. Find the `MQTT` section and turn it on.
    3. 33. Enter the values you copied in step 2: server, port, username and password.
    Shelly app connection settings
    Shelly app MQTT view. Same four values.

    Check these in the screenshot:

    1. 11. In the Shelly app, open the device settings.
    2. 22. Find the `MQTT` section and turn it on.
    3. 33. Enter the values you copied in step 2: server, port, username and password.

    If saving fails or the connection drops immediately, check you did not paste a trailing space after the password — this is the most common cause.

    Open the detailed visual guide
    Advanced: via the browser (alternative)
    You can also open the Shelly web UI directly in a browser using the device IP address. Settings are under Settings → MQTT. This is only needed in special cases — the app is easier.
  3. 5

    Check the device shows up

    Optimaatti

    When the connection works, the device appears in Optimaatti automatically.

    • Go back to Optimaatti and open the `Devices` page.
    • Wait 1–2 minutes. The device will appear in the list automatically.
    • Give it a clear name: for example `Water heater` or `Sauna stove`.
    Optimaatti Devices page
    The Devices page shows each connected Shelly on its own card.

    Check these in the screenshot:

    1. 11. Go back to Optimaatti and open the `Devices` page.
    2. 22. Wait 1–2 minutes. The device will appear in the list automatically.
    3. 33. Give it a clear name: for example `Water heater` or `Sauna stove`.

    If the device does not appear within 5 minutes, the most common cause is a typo in the password. Go back to step 4 and check each field.

Part 3 / 3 · ~2 min

First savings

Pick a device type and create a rule.

  1. 6

    Tell the app what the device controls

    Optimaatti

    Picking the device type helps Optimaatti suggest the right settings.

    • Open the device details from the list and tap `Edit`.
    • Choose the device type: water heater, heater, light control or other.
    • If the device measures electricity use, enable metering — you will see consumption on the Costs page.
    • Save.
    Device edit view with device type selection
    Device edit view: choose the device type and enable metering if needed.

    Check these in the screenshot:

    1. 11. Open the device details from the list and tap `Edit`.
    2. 22. Choose the device type: water heater, heater, light control or other.
    3. 33. If the device measures electricity use, enable metering — you will see consumption on the Costs page.
  2. 7

    Create your first rule

    Optimaatti

    Now turn on the savings.

    • Open `Rules` and tap `Create new rule`.
    • Select the device you just added.
    • Start with a simple template: `Cheapest hours` shifts usage to the most affordable times automatically.
    • Save the rule. You will see on the timeline when the device is on.
    • You can always override the automation and control the device manually.
    Rule automation: ready-made templates
    Templates: `Use cheapest power`, `Avoid expensive power`, `Keep temperature comfortable` and others.

    Check these in the screenshot:

    1. 11. Open `Rules` and tap `Create new rule`.
    2. 22. Select the device you just added.
    3. 33. Start with a simple template: `Cheapest hours` shifts usage to the most affordable times automatically.
    Consumption timeline — automation impact over time
    The timeline shows automation, thermostat baseline and outside temperature together — this is where you see savings form.

    Check these in the screenshot:

    1. 11. Open `Rules` and tap `Create new rule`.
    2. 22. Select the device you just added.
    3. 33. Start with a simple template: `Cheapest hours` shifts usage to the most affordable times automatically.

    Pick a template that matches the device type — `Cheapest hours` is a safe choice for water heaters and electric heaters.

Done — your first savings are set up!

Optimaatti now controls your Shelly based on the cheapest electricity hours. Your first savings appear on the Costs page within a couple of days.

Stuck?

Three most common issues and quick fixes:

  • Device will not connect
    Check the password (the most common cause) and that you are on the same Wi-Fi.
  • Readings keep dropping
    Check the MQTT port — usually 8883 (TLS).
  • Rule will not trigger
    Check the device clock and timezone in the Shelly app.