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19 Jan 2027
Solar, battery, heat pump, car: designing one app for the whole home
Solar, battery, heat pump and EV each ship their own app. How to design one home energy management app that gives households one clear answer.
Short answer
Design a home energy management app around the household’s questions, not around the devices. Bring solar, battery, heat pump, car and grid into one view, open on a single sentence that says what the home is doing, let routine decisions run automatically with a visible reason, and keep each device’s detail one tap down.
Picture an evening in a well-equipped European home. It’s an illustrative one, but you’ll recognise it. The inverter app says the panels made 14 kWh today. The battery app says 82% and charging. The heat pump app would like a word about the schedule. The car app suggests charging now. The wallbox app suggests waiting. The supplier’s app shows a price curve nobody asked for.
Six apps, six logins, six opinions. It’s a family group chat where every member is a machine. And the household only has one question: are we doing this right?
That home is getting more common. Europe sold 4.2 million electric cars in 2025, 28% of all new cars. Heat pump sales rose 13% to 2.9 million across 21 European countries, bringing the installed stock to 29.3 million. Every one of those devices arrives with its own app.
At Dtail Studio, a Barcelona design studio working with HealthTech and renewable energy startups, we design for the home first and treat each device as one part of it. Much of that thinking comes from our brand and product work with Cubee, an energy management startup (see the Cubee case study).
Why do homes end up with five energy apps?
Because each device is sold by a different company, and each company ships an app to prove its device works. Nobody is responsible for the home as a whole, so the homeowner becomes the integration layer.
Each app makes sense on its own. Together they contradict each other. The battery wants to store the midday sun, the car wants the same sun, and the heat pump wants to pre-heat before the evening peak. Without one place that weighs those up, the person in the kitchen does it in their head. Badly, and only on the days they remember.
There’s a market reason to fix this too. SolarPower Europe reports that residential rooftop solar fell from 28% of new EU solar capacity in 2023 to 14% in 2025. When fewer homes are buying new panels, getting more out of the kit people already own becomes the stronger pitch. That’s a software and design job.
What should a home energy app show first?
One home answer: a short sentence that tells the household what the home is doing right now and whether they need to act. Device numbers come second, for the people who want them.
Here’s how each device feeds that answer.
Solar.
What it needs to show: power now (kW), energy today (kWh), forecast for tomorrow.
The question the household is asking: is the sun paying for this?
Its line in the home answer: “Solar producing 3.2 kW”Battery.
What it needs to show: charge level, charging or discharging, time to full or empty, reserve kept for outages.
The question the household is asking: will we have power tonight?
Its line in the home answer: “Battery 82%, charging”Heat pump.
What it needs to show: room temperature against target, current mode, next scheduled change.
The question the household is asking: will the house be warm when we need it?
Its line in the home answer: “Heat pump pre-heating till 7”Car and charger.
What it needs to show: battery level, ready-by time, expected range.
The question the household is asking: will the car be ready in the morning?
Its line in the home answer: “Car ready by 8:00”Grid.
What it needs to show: importing or exporting, price now, price later.
The question the household is asking: are we paying, earning, or waiting?
Its line in the home answer: “Grid: exporting”
The home answer: all five lines collapse into one card, with a plain-words headline above them, such as “Running on sunshine. Nothing to do.” If something needs attention, the headline changes, not the layout. (Illustrative example.)
Two rules hold this together. Use kW for “right now” and kWh for “so far today”, and never put them side by side without a label. And turn numbers into outcomes wherever you can: “ready by 8:00” beats “63% state of charge”. We go deeper on units in nobody understands a kilowatt-hour.
How do you design automation people trust?
Show what the system decided, why, and how to undo it, in one line each. People accept automation when they can see its reasoning and overrule it in one tap.
A good automated decision reads like a note from a sensible housemate: “Charging the car after midnight. It’s cheaper then. Charge now instead?” A bad one quietly changes the heating and leaves the homeowner wondering whether something broke, or whether the house has started having opinions.
Practical patterns:
A decisions log.
A short timeline of what the system did today and why.Overrides that expire.
“Charge now” applies to tonight, then the plan resumes.Priorities the household sets once.
For example: car ready by 8:00 matters more than exporting to the grid.Honest states.
If the app can’t reach the heat pump, say so plainly and show the last known reading with its time.
Prices that change by the hour make all of this harder, which we cover in our post on dynamic electricity tariffs.
Which standards make one app possible?
Standards let devices from different makers share data and accept commands, so one app can see and steer the whole home. They don’t decide what the screen shows. That part is still design.
At a high level:
EEBUS is a vendor-neutral language that lets chargers, solar, heat pumps and storage talk to an energy manager. It’s recognised as international standard IEC 63380 and recommended in Germany for grid-controllable devices.
Matter, the smart home standard, added solar, batteries, heat pumps and water heaters as device types in version 1.4, alongside improvements for EV chargers.
OCPP connects chargers to the back-end that manages them, and ISO 15118 handles the conversation between the car and the charger, including charging the car on a schedule and sending power back.
For a designer, the lesson is to plan for uneven data. Some devices report everything, some only a few values, and some drop offline at the worst possible moment, which is usually during a demo. Design every card for three states: full data, partial data and no data. A card that breaks when one inverter goes quiet tells the homeowner the whole system is broken.
Cubee: one brand across decks, screens and hardware
Cubee is an energy management startup. When we met them, their technology was strong but their visual presence was fragmented. They needed to look approachable without losing credibility, and the brand had to scale across investor decks, digital product and physical hardware.
From January to April 2024 we worked on brand strategy, logo, identity, packaging and product design. We built a geometric symbol system based on energy flow and connection, a bold logomark that balances precision with warmth, and grid logic and typography that make complex information feel simple. That last part is the one that matters for a home energy app. When five devices share a screen, the grid and the type are what keep it calm.
Cubee has since passed 2,000 installations, which is down to their team.
“Dtail helped us launch with a brand and product that stood out instantly.” David Vondracek, Founder and CEO, Cubee
If you’re earlier on, start with the brand. We wrote about that in how to brand a clean energy startup and about what energy investors look at first in a pitch deck.
FAQ
What is a home energy management system?
Software, sometimes with a small hardware hub, that sees and coordinates the energy devices in a home: solar, battery, heat pump, EV charger and the grid connection. The app is the part the household sees.
Should a home energy app control devices automatically?
Yes, for routine decisions like when to charge the car or the battery. Always show why it acted and let people override it in one tap.
Do I need to support every brand of device?
No. Support the brands your installers fit most and use open standards for the rest. Then design clear states for devices you can only partly see.
Which standards should a home energy app support?
It depends on your market. EEBUS is strong in Germany, Matter is growing in consumer smart homes, and OCPP and ISO 15118 cover EV charging. Ask your installers what they fit.
What’s the difference between kW and kWh in an energy app?
kW is power right now, like speed. kWh is energy over time, like distance. Show kW for live status and kWh for totals, and label both.
The kitchen test
Hand your app to someone who lives in a home with solar and an electric car. Give them ten seconds on the home screen, then ask three questions. Are we using our own power right now? Will the car be ready tomorrow morning? Is now a good time to run the dishwasher? Every question they can’t answer is a screen you haven’t designed yet.
Building an app for a home full of devices? We’d love to hear about it.
About the author. Slavena Vasileva is a partner and brand strategist at Dtail Studio, a senior brand and product design studio in Barcelona working with HealthTech and renewable energy startups. 16+ years, 300+ projects, 5.0 on Clutch.
Sources: IEA, Global EV Outlook 2026: Trends in electric cars · European Heat Pump Association, Market data · SolarPower Europe, EU hits 2025 solar target but market contraction puts 2030 goal at risk (December 2025) · Connectivity Standards Alliance, Matter 1.4 enables more capable smart homes (November 2024) · Bender, EEBUS: the communication standard for the energy transition · Cubee case study
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