What is predictive control (MPC) and why does it save electricity with Shelly devices?

Introduction: why fixed schedules are no longer enough

Many homes already have smart plugs and timers. You can, for example, run a water heater at night and turn it off during the day. The problem is that:

• electricity prices change hour by hour
• weather and outdoor temperature vary
• a building is “slow” — it reacts with a delay

A fixed schedule doesn’t understand these realities. You need control that anticipates the future and can make sensible decisions automatically. This is where predictive control (MPC) (Model Predictive Control) comes in.

What is MPC?

MPC is a control method used for years in industry and energy systems. The simplified idea:

• Build a model of what you control (e.g., a water heater, indoor temperature, an EV battery).
• Predict the future:
  • how the device behaves under different control actions
  • what prices look like in the next hours
  • what load/temperature is coming.
• Create a plan: software evaluates alternatives and chooses the one that stays within your limits (comfort, temperature, readiness) at the lowest cost and with high efficiency.

In practice predictive control (MPC) answers:

How should I run this device during the next 24–48 hours so it behaves the way I want, but as cheaply and efficiently as possible?

How does predictive control (MPC) relate to Shelly devices?

Shelly devices are the “hands and feet” in your home:

• A Shelly relay can control a water heater, underfloor heating, or electric radiators.
• A Shelly Plug can control a dryer or another large load.
• Shelly EM/3EM can measure consumption per phase.

When predictive control (MPC) is combined with Shelly:

• MPC computes the best schedule for your loads.
• Shelly devices execute it in practice: on/off, power limits, measurement feedback.
• The system can consider market prices, outdoor temperature/forecast, your usage profile and comfort limits.

Example: a water heater and market-based electricity

Imagine a 300-liter electric water heater.

Without smart control:

• It heats whenever the thermostat calls for it.
• It doesn’t care about price. If temperature drops during an expensive hour, it still heats.

With predictive control (MPC) + Shelly:

• The system knows typical hot-water demand (mornings, evenings).
• It sees hourly prices.
• It models how fast the tank cools.

So it can plan, for example:

• Pre-heat slightly during cheap hours before prices rise.
• Avoid heating at the peak, as long as temperature stays within your comfort limits.
• Ensure there’s enough hot water in the morning.

Result:

• Same comfort, but energy shifts to cheaper hours.
• Lower cost and often lower emissions.

Example: EV charging

Many people want:

• the car to be at 80% by 7 AM
• but to charge during the cheapest hours

A simple timer is hit-or-miss. Predictive control (MPC) + Shelly can:

• estimate how many kWh are needed to reach the target
• look at the next day’s price distribution
• decide when charging should start/stop to meet the goal at the lowest cost

It can also respect:

• maximum power limits (main fuse)
• other simultaneous loads (water heater, sauna)

What’s the benefit for you?

• Money: shift consumption to cheap hours → lower bill
• Comfort: you don’t need to micro-manage — predictive control does it
• Safety & limits: predictive control respects temperature and power limits
• Environment: consumption lands more often in cleaner production hours

Summary

Predictive control (MPC) makes Shelly devices much more than remote switches. It brings:

• industry-grade planning
• intelligent anticipation
• continuous adaptation to prices and conditions

The outcome: less waste, a smaller electricity bill, and better results without sacrificing everyday comfort.