Can the app read smart meters automatically?

Not portably. Smart meter data access differs by country and utility and usually needs an approved integration, so start with manual readings and a camera photo. That already beats a spreadsheet, and a utility API can be added later for one market where it is open.

How do I calculate cost between two readings with time-of-use tariffs?

Interpolate usage evenly across the hours between the two readings, then apply each band’s rate to the hours it covers, plus the standing charge per day. It is an estimate, which is why the Bills screen exists: comparing against a real bill shows the user how close the estimate runs.

How to Build a Home Energy Tracker App with AI (2026)

What a home energy tracker app needs

Meter readings for electricity, gas, and water with photo of the dial
Tariffs with unit rate, standing charge, and time-of-use bands
Usage and cost charts by day, week, and month
Bill reconciliation: compare the tracker to the actual bill
Solar generation and export readings with a net view

The screens

Screen	What it does
Home	This week’s cost so far, versus last week and the same week last year
Add Reading	Pick the meter, type the reading, optional photo of the dial
Meters	Each meter with its tariff and reading history
Charts	Usage and cost by day, week, month; filter by meter
Bills	Enter a bill and compare it to what the tracker calculated

The data model

Meter: name, type (electricity, gas, water, solarGeneration, solarExport), unit, serialNumber
Tariff: meterId, name, standingChargePerDay, bands (label, startTime, endTime, ratePerUnit), validFrom
Reading: meterId, value, readAt, photoUri, source (manual, estimated)
Bill: meterId, periodStart, periodEnd, amount, unitsBilled

The build prompt (copy this)

Paste this into ShipNative and it becomes a working React Native app with these screens, navigable in a live preview, in about two minutes:

“A home energy tracker app for households. Home shows this week’s estimated cost so far across all meters, compared to last week and to the same week a year ago, with a one-line verdict such as “12% lower than last week”. Add Reading lets the user pick a meter, type the current reading with a numeric keyboard, and optionally photograph the meter dial; it validates that the reading is not lower than the previous one and warns on an unusual jump. Meters lists electricity, gas, water, and optional solar generation and export meters, each with its tariff (unit rate, daily standing charge, and optional time-of-use bands) and a reading history. Charts shows usage in units and cost in money by day, week, and month, interpolating between readings, with a toggle per meter and a net view for solar homes that subtracts export income. Bills lets the user enter an actual bill for a period and shows the difference versus the tracker’s estimate so they can spot a wrong tariff or an estimated bill. Reminders prompt a reading on a chosen day each week. Works offline; data stays on the device with optional backup. Screens: Home, Add Reading, Meters, Charts, Bills.”

Then iterate with small, screen-specific prompts (“make the primary button bigger”, “add an empty state”), preview on your own phone, and export the full Expo project whenever you want. The full method: how to build an app with AI.

How it makes money

Freemium: one electricity meter and basic charts free, with a small annual subscription unlocking multiple meters, solar, bill reconciliation, and export. Households motivated by rising bills will pay a few dollars a year for something that visibly saves more; keep the price well below one month of the saving it helps find. Avoid affiliate tariff-switching links unless you are prepared to maintain them per country.

Implementation and the revenue math for every model: how to make money from an app. When you’re ready to ship: App Store and Google Play publishing guides.

Build it now

The prompt above is free to run at shipnative.dev — working home energy tracker app on your phone today, full code export.

How to Build a Home Energy Tracker App with AI