Prepayment energy for rented properties
Tenants top up their electricity online, the system sends the credit to their smart meter, and landlords see everything in one place.
- 3audiences, one system
- 24/7meter monitoring
- 1,800+changes since 2023
The client
A company that supplies and manages prepayment electricity meters for landlords of flats and shared houses.
The challenge
Prepayment meters only work if tenants can top up quickly, at any hour, and the credit reaches the meter reliably. Each building has its own tariff and standing charges, tenants come and go, and the meters themselves sit behind the manufacturer's own control system. The client needed one service for tenants, landlords and its own staff, connected directly to the meters.
For tenants
- Balance and usage charts on any device
- Top-ups by card online, or with cash at any PayPoint shop
- Automatic top-ups when credit runs low, using a saved card
- Texts and emails when credit is low, or if a top-up is slow to reach the meter
For landlords and the client's staff
- Buildings, flats, meters, tenancies and tariffs in one place, with the full history
- Day and night rates and standing charges, set per building and sent to the meters
- Meters can be moved between flats and buildings, and buildings between landlords
- Reports that catch any meter running on a different tariff from the one it should have
- Payment history, and payments posted straight into the accounts
- A meter shop where landlords order meters and parts, with VAT-inclusive pricing
- Staff permissions down to which meter alerts each role can see
Talking to the meters, around the clock
A background service runs more than a dozen scheduled jobs. It sends credit to meters, checks balances, collects readings and alerts, applies standing charges, writes tariffs to the meters and reads them back to check they took. If a top-up doesn't reach a meter, it tries again on a set schedule and tells the tenant. Every job is logged, and staff can see at a glance that everything is running.
Technical details
Two ASP.NET Core Razor Pages portals (tenant, and landlord/admin) on .NET 8 over about 50 shared projects, with EF Core 9 and SQL Server (around 195 migrations). Hosted on Azure with Key Vault for secrets and Application Insights for monitoring.
The meter manufacturer's head-end (HES) API is wrapped behind an abstraction from a Swagger-generated client. A heartbeat service runs tasks for credit pushes, balance polling, meter events, time-of-use tariff write and read-back verification, standing charges, recharge retries and the Xero queue.
Stripe Payment Intents with 3-D Secure, saved cards for auto top-up and webhooks; PayPoint through an OpenAPI-generated client; Xero over OAuth 2; Twilio SMS. Around 300 automated tests cover the tariff, standing-charge and top-up logic.
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