Energy management for small businesses — without a building-automation budget
A traditional building management system is priced per square metre and needs an integrator. Most small businesses only need three things: see what they use, see what it costs, and run the loads that can wait in the cheapest hours. Shelly Pro hardware and Elewatt do exactly that.
Why small businesses skip energy management
A building management system typically costs €25–75 per square metre, and projects for small buildings run from tens of thousands to hundreds of thousands. Under about 500 m², the payback is slow. KNX, the common alternative, is around €8–25k even for a single home.
So most small businesses do nothing. In the EU's 2024 Eurobarometer survey, SMEs named complex procedures (35%) and high costs (28%) as the main barriers to resource efficiency, and only 23% used any outside help. Energy management ends up as a monthly bill nobody has time to read.
Typical BMS cost
€25–75/m²
plus integrator and programming
Shelly Pro 3EM-3CT63
≈ €131
real-time 3-phase metering
Business plan
20 devices
5 contracts, extendable
BMS vs. Shelly Pro + Elewatt
A BMS does far more — ventilation, access control, alarms. If you need those, you need one. If you need metering and price-based control of a handful of big loads, you don't.
| Traditional BMS | Shelly Pro + Elewatt | |
|---|---|---|
| Priced by | Square metre | Load you control |
| Installation | Integrator project | An electrician, in hours |
| Who changes the settings | The integrator | You, in the browser |
| Consumption and cost | Often an add-on | Real time, with the day's spot price |
| Spot-price control | Custom programming | Built in |
| Mixed brands | One vendor's ecosystem | Shelly, Daikin, Samsung, Home Assistant, evcc |
- Traditional BMS
- Square metre
- Shelly Pro + Elewatt
- Load you control
- Traditional BMS
- Integrator project
- Shelly Pro + Elewatt
- An electrician, in hours
- Traditional BMS
- The integrator
- Shelly Pro + Elewatt
- You, in the browser
- Traditional BMS
- Often an add-on
- Shelly Pro + Elewatt
- Real time, with the day's spot price
- Traditional BMS
- Custom programming
- Shelly Pro + Elewatt
- Built in
- Traditional BMS
- One vendor's ecosystem
- Shelly Pro + Elewatt
- Shelly, Daikin, Samsung, Home Assistant, evcc
Where it pays off, by sector
The loads that save the most store energy or run on a flexible clock. Typical sizes below — check your own nameplates.
Restaurants, cafés, hotels, gyms
Hot-water tanks of 3–9 kW heat for hours and hold the heat. Heat them in the cheapest hours before service; pre-heat dishwasher tanks before opening.
Spas and saunas
Commercial sauna heaters are 12–15 kW on three phases. The pre-heat before opening can move into cheaper hours; switch them through a contactor.
Pools
A filtration pump of around 1.7 kW needs 6–12 hours a day — any 6–12 hours. That makes it one of the easiest loads to schedule by price.
Offices and shops
Pre-heat or pre-cool before opening. Electric radiators run on relays; Daikin and Samsung heat pumps and air conditioners are controlled through their clouds.
Fleets and staff parking
Company cars that stand overnight can charge in the cheapest hours. With evcc, Elewatt supplies the prices; simpler chargers switch through a contactor.
Farms
Grain-drying fans, water pumps and ice-bank milk cooling can shift. Direct milk cooling has to follow milking, so it stays as it is.
What not to switch with a relay
Price automation is for loads that can wait. Keep these out of it:
- Freezers and cold rooms with food-safety (HACCP) limits — frozen goods must stay at −18 °C.
- Lifts, ventilation, fire and safety systems.
- Motors and compressors switched directly — use a contactor, fitted by an electrician.
- Frost protection circuits.
Heating and cooling with Daikin
Heating and cooling are the biggest electric loads in most premises. Elewatt connects to Daikin units through the Onecta cloud: it raises the setpoint in cheap hours and backs it off in expensive ones, so the building stores heat — or cool — when electricity is cheap. Samsung air conditioners work the same way through SmartThings.
See consumption and cost for every site
Clamp a Shelly Pro 3EM-3CT63 in each site's board and Elewatt shows its consumption and cost in real time, priced with that site's own contract and grid fees. Metered relays add a savings figure per device. Each site can have its own contract and price area.
Solar on the roof?
Shelly's Pro meters measure import and export, and Shelly's photovoltaic guide shows how businesses use them to send surplus solar into water heaters. Elewatt handles the other side: shifting grid consumption to the cheapest hours.
Getting started
Start with one site and the loads you already know are big.
- 1
Meter one site
An electrician fits a Shelly Pro 3EM-3CT63 in the distribution board. Connect it to Elewatt and add the site's electricity contract and grid operator.
- 2
Find the shiftable loads
Use a week of data and the calculator below to rank water heaters, saunas, heating and chargers by how much they would save.
- 3
Add relays
Metered Pro 1PM, 2PM or 4PM relays for single-phase loads up to 16 A; a Pro 3 or a contactor for 3-phase and heavier loads.
- 4
Create price filters
For each load, pick how many cheap hours it needs per day and link it to the filter. Elewatt switches it every day as prices change.
- 5
Roll out to the next site
Copy the setup to other sites. The Business plan includes 5 contracts and 20 devices and can be extended.
Estimate the savings for your premises
The calculator starts with an office: pre-heating, a water heater and fleet charging. Switch to the restaurant preset or enter your own devices.
Savings Calculator
Estimate how much you could save by running your device during the cheapest hours.
List only devices that can wait for cheaper hours. Click a row to see its hours on the chart.
Spot price + grid fees + taxes, Estonia · c/kWh (12-month avg)
Daily usage
137.0 kWh/day
Annual usage
50005 kWh/year
Without Elewatt
27.1 c/kWh avg
13569 €
per year
With Elewatt
12.9 c/kWh avg
6431 €
per year
Your savings
Monthly
595 €
Yearly
7138 €
Shelly hardware (346 €) pays back in
0.6 months
Estonia: spot prices over the last 12 months + grid fees (Elektrilevi) + taxes and VAT. "Without Elewatt" assumes running during the most expensive hours. Actual savings vary by grid package and season.
The Shelly Pro lineup: switchboard hardware without the BMS price
Shelly's Pro devices mount on a DIN rail in the distribution board, connect over Ethernet as well as Wi-Fi, and run the same scripting and schedules as the rest of the Shelly range. An electrician fits them like any other switchboard module, and Elewatt drives them through Shelly Cloud. Shelly sells the Pro line with a 5-year warranty.
| Device | What it does | Use it for | Price |
|---|---|---|---|
| Shelly Pro 3 | 3 relays, 16 A each (48 A total). Switches three separate circuits or one 3-phase load. No power metering. | 3-phase sauna heaters, large water heaters, contactor coils for bigger loads | 90 € |
| Shelly Pro 3EM-3CT63 | 3-phase energy meter, 0–63 A. The CT clamps straight over a breaker. Keeps 60 days of 1-minute data. | Real-time consumption and cost of a sub-board, a 3-phase circuit or a whole flat | 131 € |
| Shelly Pro 4PM | 4 relays, 16 A each (40 A total), with per-channel metering and a small screen. | Radiators by zone, several water heaters, one device per stairwell or room group | 118 € |
| Shelly Pro 2PM | 2 metered relays, 16 A each (25 A total). | Two single-phase loads where you want savings per device | 100 € |
| Shelly Pro 1PM | 1 metered relay, 16 A. | A single water heater or radiator circuit with its own savings figure | 76 € |
| Shelly Pro EM-50 | Single-phase meter with two 50 A clamps, plus a 2 A relay to drive a contactor. | Metering a single-phase flat or cottage; switching a load through a contactor | 102 € |
| Shelly Pro 3EM-400 | 3-phase meter, 0–400 A. | The main incomer of a larger building | 274 € |
- What it does
- 3 relays, 16 A each (48 A total). Switches three separate circuits or one 3-phase load. No power metering.
- Use it for
- 3-phase sauna heaters, large water heaters, contactor coils for bigger loads
- Price
- 90 €
- What it does
- 3-phase energy meter, 0–63 A. The CT clamps straight over a breaker. Keeps 60 days of 1-minute data.
- Use it for
- Real-time consumption and cost of a sub-board, a 3-phase circuit or a whole flat
- Price
- 131 €
- What it does
- 4 relays, 16 A each (40 A total), with per-channel metering and a small screen.
- Use it for
- Radiators by zone, several water heaters, one device per stairwell or room group
- Price
- 118 €
- What it does
- 2 metered relays, 16 A each (25 A total).
- Use it for
- Two single-phase loads where you want savings per device
- Price
- 100 €
- What it does
- 1 metered relay, 16 A.
- Use it for
- A single water heater or radiator circuit with its own savings figure
- Price
- 76 €
- What it does
- Single-phase meter with two 50 A clamps, plus a 2 A relay to drive a contactor.
- Use it for
- Metering a single-phase flat or cottage; switching a load through a contactor
- Price
- 102 €
- What it does
- 3-phase meter, 0–400 A.
- Use it for
- The main incomer of a larger building
- Price
- 274 €
Prices from the shelly.com EU shop including VAT, checked on 29 September 2026. They vary by country and retailer.
Over 16 A? Use a contactor
A Shelly relay is rated 16 A per channel. Heavier loads, and anything with a motor or compressor, should be switched by a contactor that the Shelly controls — standard switchboard work for an electrician, and the way Shelly itself recommends load shedding.
Monitoring, not billing
Shelly meters are accurate to about 1% but they are not MID-certified — Shelly says its devices are not designed for MID. Use them to see and allocate consumption. Where the law requires a certified meter to bill per kWh, keep the certified meter for billing.
Shelly's statement on MID →Shelly's own guides for buildings
Shelly publishes its own material for property managers and installers:
Running equipment we don't support yet?
Tell us which systems and brands you use — BMS, heat pumps, chargers, meters. We check every request and build integrations in order of demand.
See what your business spends on electricity — hour by hour
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