Orchestrating the Big Three: EV, Heat Pump, and Home Battery with Homey
You have invested in the "holy trinity" of sustainable living: an EV, a heat pump, and a home battery. Individually, they are powerful. Together, without an orchestrator, they can be chaotic—fighting for available power, tripping fuses, or draining your battery at the wrong time.
Homey is the orchestrator that brings all three together. By letting these devices talk to each other, you can move from a house that consumes energy to a home that uses it wisely. This guide combines the strategies for EV charging and heating into a single, cohesive plan to maximize self-consumption, minimize costs, and keep your home comfortable.
The Challenge: Managing the Heavyweights
Your EV and heat pump are likely the biggest energy consumers you own. A single EV charging session can consume 10 to 30 kWh, while a heat pump runs for hours to maintain comfort.
- The Electric Vehicle is a high-power burst consumer. It needs a lot of energy quickly but is flexible about when it gets it (as long as it is full by morning).
- The Heat Pump is a slow-burn consumer. It relies on efficiency (COP) and works best with stability, not rapid switching.
- The Home Battery is the buffer. It is not large enough to fill the car or run the heat pump for days, but it is perfect for smoothing out the gaps between the two.
The Three Core Strategies
To make these devices work in harmony, we use three layers of logic in Homey.
1. The Solar-First Strategy (Daytime)
When the sun is shining, your home becomes a generator. Instead of selling that power for a low fee, you use it. When solar production is high and there's a surplus, you electric vehicle starts charging automatically. Homey ensures this happens smoothly, buffering short cloud cover with the home battery so the charger doesn't toggle on and off constantly.
Furthermore, you use the house itself as a battery. When solar power is abundant, Homey slightly increases the room temperature (for example, by 0.5 to 1.0 degree). This "pre-heating" stores thermal energy in your floors and walls, meaning the heat pump can work less hard in the evening.
When there aren't consumers that need energy, you store in your home battery. Homey directs the solar surplus to your ESS and saves it, so it can be used on-demand later.
2. The Price-First Strategy (Nighttime)
If you have a dynamic energy contract, you'll find electricity prices often drop at night. This is the prime time to charge your EV. You set a price limit in Homey Flows, and the car fills up when electricity is cheapest.
If prices are exceptionally low, Homey can force-charge your home battery to ensure you start the day with a full buffer. Similarly, a gentle morning pre-heat during cheap hours prevents your heat pump system from having to work hard during the expensive morning peak.
3. Peak Shaving (The Referee)
Peak shaving is one of the most critical roles for Homey. What happens when the oven is on, the shower is running, and the car is charging?
The system first throttles the EV charger. If that isn't enough, it briefly pauses the heat pump's electric backup heater to shave the peak. At the same time, the home battery discharges to fill the gap and answer your demand. This orchestration keeps your house running safely even when your appliances are working at once.
The Priority Matrix: Who Goes First?
You cannot do everything at once. You need a hierarchy of needs, which you can program into Homey using simple logic variables.
- Safety & Comfort (Top Priority): The house must be warm, and the car must have enough range to reach work. These rules override everything else.
- Self-Consumption: Using your own solar power.
- Peak Shaving: Protecting the grid connection comes next.
- Price Arbitrage: Filling up when energy is cheap.
Practical Logic for Your Homey Flows
Here is how to translate these strategies into actual behavior for your home.
The "Departure Certainty" Rule (EV)
No matter what the sun or prices do, you need to drive. For instance, you create a Flow that checks the car battery each day at 6:00 AM. If it is below your minimum required level (e.g., 40%), start charging immediately regardless of cost. This ensures you never get stranded.
The "Sunny Day" Pre-Heat (Heat Pump)
Use your solar panels to relieve the evening load. If solar output is strong and the home battery is reasonably full, increase the living room thermostat by a small amount (e.g., 0.5 degrees), even when you aren't home.
At the same time, monitor the outdoor temperature. If it is extremely cold, the heat pump is less efficient, and it might be better to save the solar power for the EV or home battery.
The "Cooking Peak" Guard
Dinner time is often the most expensive and power-intensive time of day. When the induction cooktop and oven are running, Homey detects a spike in power usage. To balance things, Homey automatically pauses the EV charger and prevents the heat pump from starting a new cycle. The home battery discharges to cover the cooking load. Once the kitchen is quiet, normal operations resume.
The Battery Buffer Rule
Your home battery is precious and you shouldn't drain it to charge the car. If the EV is charging, do not allow the home battery to discharge to help it, unless it is to prevent a fuse trip. Save the home battery for lights, entertainment, and the fridge—loads that run when the sun is down.
Getting Started: A Phased Approach
Don't try to build this all in one day.
- Phase 1: Insight. Connect your P1 meter, EV charger, and inverter to Homey. Watch the data for a week. When do peaks happen? How much solar do you actually export?
- Phase 2: The Basics. Set up the "Departure Certainty" rule for the car and the basic "Peak Shaving" safety net.
- Phase 3: Solar & Price. Add the logic to charge the car and pre-heat the house based on solar surplus and dynamic prices.
- Phase 4: Fine Tuning. Adjust your thresholds. If the house gets too hot, reduce the pre-heat temperature. If the car isn't charging enough on sun, lower the solar trigger threshold.
Conclusion
By combining your EV, heat pump, and battery into one Homey-controlled ecosystem, you stop them from competing and start them collaborating. The heat pump pre-loads comfort, the EV snatches up cheap power, and the battery smooths out the edges. The result is a home that is lower in cost, higher in comfort, and resilient against peak charges—all happening automatically in the background.
FAQs
Do I need a home battery to make this work?
No. You can achieve significant savings just by timing your EV charging and heat pump cycles to match solar production or cheap prices. The battery simply acts as a helpful buffer to smooth out clouds or cooking peaks.
Will pre-heating make my house too hot?
Not if done correctly. We recommend small increases, such as 0.5 to 1.0 degrees Celsius. This is usually barely noticeable but stores enough energy to delay the heating system from turning on during expensive evening hours.
Can I prioritize my car over the heat pump?
Yes. In Homey, you can create a variable for "Priority." If you need to leave soon, the car gets the power. If it's a freezing night, the heat pump gets the power. You decide the hierarchy.
What happens if the internet goes down?
Homey Pro runs its flows locally. As long as your internal network (Wi-Fi/LAN) is functioning, your peak shaving and charging logic will continue to work without an internet connection.
Is it bad for my home battery to charge my car?
Generally, you want to avoid cycling your home battery just to fill the car, as it wears out the home battery and incurs conversion losses. It is better to use the home battery for household loads and use the grid (or direct solar) for the car, except when peak shaving.
Glossary
COP (Coefficient of Performance)
A measure of a heat pump's efficiency. A COP of 4 means that for every 1 kWh of electricity used, the pump produces 4 kWh of heat.
Peak Shaving
The process of reducing power consumption during times of maximum demand to avoid tripping fuses or paying higher capacity tariffs.
Departure Certainty
A logic rule ensuring that an electric vehicle always has a minimum required charge by a specific time, regardless of energy cost.
Hysteresis
A programming technique used to prevent devices from rapidly switching on and off. It sets different thresholds for starting and stopping (e.g., start charging at 1500W solar, stop at 800W).
Thermal Mass
The ability of materials in your home (like concrete floors or brick walls) to absorb and store heat, releasing it slowly over time.
