Shelly relay for spot price automation | SaveElectro
Integrations · Shelly · Buying guide
Which Shelly relay to buy for spot-price automation
Spot-price automation (pörssisähkö-ohjaus) switches a heavy appliance on when electricity is cheap and off when it is expensive. A Shelly relay is the hardware that does the switching. This page helps you pick the right one and prepare for the installation.
Early access. You can connect and configure a Shelly device in Automation today. The automation itself, SaveElectro switching your appliance in a cheap window, is still in development. The Home Assistant Blueprints work today. For the full picture, see Shelly device automation.
The short answer
For one appliance up to 16 A, buy a relay with power metering: the Shelly 1PM Gen3. Metering lets SaveElectro show the real energy shifted into cheap hours once the automation launches. A relay without metering, such as the Shelly 1 Gen3, is cheaper but cannot measure consumption.
🔌Shelly 1PM Gen3Recommended
The model we build and test against.
Max load16 A
Power meteringYes
Best forOne load up to 16 A
🆕Shelly 1PM Gen4Not confirmed yet
Newer, adds Zigbee and Matter. Not confirmed with SaveElectro yet, so Gen3 is the safe choice today.
Max load16 A
Power meteringYes
If your electrician prefers to mount the relay in the fuse cabinet, ask about DIN-rail models such as the Shelly Pro 1PM. We have not tested those.
Which appliance are you automating?
💧Water heaterIn development
The classic first project. The tank stores heat, so it can wait for the cheapest hours without you noticing. A 3 kW single-phase heater draws about 13 A, close to the 16 A relay limit. Bigger or three-phase heaters need a contactor, which is your electrician's decision.
🌡️Room heating (convectors)In development
Nordic convectors are typically 400 W to 2 kW, which leaves plenty of headroom on a 16 A relay. Each convector gets its own relay and its own schedule.
🔋Battery charging (reserve power)In development
This is for a standalone battery with its own charge controller, such as a portable power station. It is not for an integrated home battery such as a Tesla Powerwall or BYD Battery-Box. Those have their own grid-charging schedule and should not be switched by a generic relay.
Also possible with Shelly, but not in SaveElectro yet
Shelly can switch more than the three cases above. These are not part of SaveElectro's automation yet. Tell us which one you would like first: [email protected].
♨️Electric floor heatingNot tested
Floor heating (lattialämmitys) circuits can be larger and have their own thermostats, and we have not tested this case. Ask your electrician, and write to us before you buy.
🌬️Heat pump (SG Ready)Not supported yet
Many heat pumps have an SG Ready input: two potential-free contacts that choose one of four modes, from blocked to ordered. Shelly relays are used to drive those contacts, and Shelly's own knowledge base shows an example. The heat pump decides how far it follows the signal, and the wiring is installer work.
🚗Car heater (autolämmitin)Not supported yet
Car interior heaters are typically 900 W to 1900 W. Shelly's Outdoor Plug S Gen3 is rated 12 A / 2500 W for resistive loads and is IP44, so it can fit a car-heater socket. Check the heater's start-up power against that limit. Many car-heater timers start heating about two hours before departure.
What we do not switch with a relay, and why
We checked these before writing this guide. A relay is the wrong tool for them, so we would rather say so than point you to a risky setup.
🧖Sauna heaterNot via a relay
A sauna heater that can be started remotely must have a door switch or pass the cover test (standard EN 60335-2-53), because the danger is laundry or other flammable material left on or near the stove. That safety lives in the heater's own control system, and a generic relay is not part of it. We found no Shelly product certified for this. Use your heater manufacturer's own remote-control system; SaveElectro's planner tells you the cheapest time to start heating. Tukes: sauna electrical installations (in Finnish)
🧺Washing machine, dishwasher, dryerNot via a relay
Many appliance manuals say not to power these through an external timer or switch, and a Finnish home insurer advises running them only when you are at home. SaveElectro tells you when a cheap window opens, and you press Start.
🔌EV chargerCharger's own control
Wallboxes are normally scheduled through their own app, API or OCPP, which is how Shelly's own EV charging example works. A relay only suits a charger designed for external control, so check its manual first. SaveElectro does not switch chargers yet; it tells you the cheapest hours to set on the charger.
⚠ A note on safety. A relay that switches a water heater or heating circuit is part of the fixed electrical installation. In Finland that work is reserved for an authorised electrician (sähköasentaja), and rules in other countries differ. SaveElectro does not give wiring instructions.
What to ask your electrician
Is the circuit within the relay's 16 A limit with some margin, or does the load need a contactor?
Where will the relay sit: in the fuse cabinet (DIN-rail model) or behind a socket or junction box?
Is Wi-Fi reliable at that spot? The relay connects over Wi-Fi.
Will the appliance's own thermostat and safety cut-outs stay in the circuit? They should.
Can they supply the relay themselves? Many electricians install what they supply. Tell them the exact model.
How it works with SaveElectro
01
🔧
Your electrician installs the relay
You connect it to Wi-Fi with the Shelly app.
02
🔗
Connect it in Automation
Link the device to your SaveElectro account in Automation and choose what it controls.
03
💰
The automation switches it
When the automation goes live, SaveElectro switches the appliance in cheap windows using Nord Pool prices for your country and your price rules, and shows the real energy it shifted.
An illustrative day with made-up prices, not live data. The appliance runs when the price is at or below the limit you set (dashed line). White marks show when it would run.
Where to buy
Shelly relays are sold by electrical wholesalers, installers and online retailers in the Nordics and Baltics. Ask your electrician to supply it, or buy from a retailer you trust. SaveElectro does not sell hardware and earns nothing from the links on this page.
Not out of the box. The Shelly app schedules by clock time and does not switch by spot price. You need a script, Home Assistant, or a service that reads the pörssisähkö prices and switches the relay. That is what SaveElectro's Shelly connection is built to do.
What is the maximum load of a Shelly 1PM?
16 A at 240 V AC per relay (Shelly 1PM Gen3 and Gen4). A 3 kW single-phase water heater draws about 13 A at 230 V, so it fits with little margin. Larger loads and three-phase heaters need a contactor chosen by your electrician.
Shelly 1PM Gen3 or Gen4?
Both switch up to 16 A and measure power. Gen4 adds Zigbee and Matter. SaveElectro is built and tested against Gen3. We have not confirmed Gen4 yet, so Gen3 is the safe choice today.
Can I install the relay myself?
Not if it is wired into a water heater or heating circuit. That is part of the fixed installation and must be done by an authorised electrician (sähköasentaja in Finland). Plug-in smart plugs need no wiring, but SaveElectro does not support them yet.
Do I need Home Assistant?
No. Home Assistant is optional for people who already use it, and our Blueprints work today. The SaveElectro Shelly connection does not require it.
Does SaveElectro sell Shelly devices?
No. We do not sell hardware, and we earn nothing from the links on this page. We tell you which models we build and test against.
Can I control a sauna heater with a Shelly?
Not with a generic relay. The sauna heater standard (EN 60335-2-53) requires a heater that can be started remotely to have a door switch or pass the cover test, so the safety sits in the heater's own control system. Shelly sells relays and plugs that people use for saunas, but we found no Shelly product certified for this. Use your heater manufacturer's own remote-control system.
Can a Shelly control a heat pump?
Often, if the heat pump has an SG Ready input. SG Ready uses two potential-free contacts to choose one of four modes, and Shelly relays are used to drive them. Wiring is installer work, and the heat pump decides how far it follows the request. SaveElectro does not control heat pumps yet.
Can I switch a washing machine, dryer or EV charger with a Shelly?
Not washing machines, dryers or dishwashers. Many appliance manuals say not to power them through an external timer or switch, and a Finnish home insurer advises running them only when you are at home. EV chargers are normally scheduled through their own app, API or OCPP, and a relay only suits a charger designed for external control. SaveElectro tells you the cheapest hours instead.
Ready to connect a Shelly?
Connecting and configuring is open now in Automation. Questions about your setup? Write to [email protected].