Energy Backbone: Smart Meter Management with Prepaid Billing and Offline-Capable Gateways

Marinas, campgrounds, and co-working spaces share a common challenge: managing electrical power distribution to individual tenants. Traditional metering is manual, billing is imprecise, and there is no way to cut off power when a prepaid balance runs out. Energy Backbone is a complete smart meter management solution that brings real-time consumption monitoring, prepaid wallet billing with automatic power cutoff, and an offline-capable gateway architecture to any location that needs granular energy management.

The Problem

Shared-space operators — whether managing a marina with 50 boat slips, a campground with seasonal visitors, or a co-working facility — face several interrelated problems with energy management:

• No Real-Time Visibility: Operators cannot see how much power each tenant is consuming until the monthly meter reading
• Billing Lag: Invoicing happens weeks after consumption, leading to disputes and uncollectable debts
• No Prepaid Option: There is no mechanism to let tenants prepay and automatically manage their budget
• Connectivity Gaps: Many locations (especially marinas and campgrounds) have unreliable internet, making cloud-only solutions impractical
• Manual Intervention: Switching power on/off requires physical access to breakers or meters

When a boat owner leaves the marina owing three months of electricity, the operator has no recourse. Prepaid billing with automatic cutoff eliminates this problem entirely.

The Solution

Energy Backbone combines Tuya-compatible smart meters, a cloud management platform, and optional local Raspberry Pi gateways into a complete system. It supports two connection modes: Cloud Mode for locations with reliable internet (polling via Smart Life API every 3 minutes) and Gateway Mode for offline-capable operation (real-time readings every 5 seconds with background cloud sync).

The prepaid wallet system is the core innovation: tenants top up their balance via Stripe, Mollie, or bank transfer (with EPC QR code support), and the system automatically cuts power when the balance depletes. Low-balance notifications give tenants time to top up before cutoff.

Key Features

For Tenants

• Dashboard — View balance, consumption overview, and alerts at a glance
• Real-Time Monitoring — Live power (watts), voltage, current, and energy readings
• Wallet Management — Top-up via multiple payment providers
• Usage History — Detailed consumption charts and statistics over time
• Notifications — Low balance and high consumption alerts

For Administrators

• Location Management — Configure multiple locations with custom pricing per kWh
• Remote Meter Control — Switch relays on/off from the admin panel
• User Management — Manage tenants and assign meters to individuals
• Gateway Monitoring — Track gateway status, connectivity, and sync health
• Billing Overview — Transaction logs, revenue reports, and financial summaries
• Data Backfill — Recover historical data from the Tuya cloud automatically

Technical Capabilities

• Dual Connection Modes — Cloud API polling or local gateway with real-time readings
• Automatic Gap Detection — Identifies and backfills missing data points
• Budget Monitoring — Cuts power when wallet balance reaches zero
• Offline Operation — Gateway continues metering and enforcing cutoffs without internet
• Data Aggregation — Compresses high-frequency readings for long-term storage

Looking Ahead

Energy Backbone addresses a real gap in the market for small-to-medium facility operators who need smart metering without enterprise complexity. By combining IoT hardware (Tuya smart meters), modern web technology, and a thoughtful offline-first gateway architecture, it delivers a solution that works reliably in environments where internet connectivity cannot be taken for granted. The prepaid wallet model transforms energy from a billing headache into a self-service system that benefits both operators and tenants.

What I Learned

Energy Backbone sits at the intersection of IoT hardware, fintech, and real-time data engineering. Each domain brought its own surprises.

IoT Reliability is Deceptively Hard

Tuya-compatible smart meters are inexpensive and widely available, but their cloud API is designed for consumer home automation — not precision billing systems. The polling interval is 3 minutes minimum, readings occasionally go missing without error messages, and the API rate limits are aggressive. Building the gap detection and backfill system was essential before any billing logic could be trusted. The lesson: never trust IoT data as ground truth without sanity-checking it against expected ranges and flagging gaps.

Offline-First Architecture for Real-World Deployments

The Gateway Mode (Raspberry Pi running locally) was the most technically interesting part of the project. A marina’s internet connection may be a consumer DSL line shared among 50 boats. Designing the gateway to operate fully autonomously — reading meters every 5 seconds, enforcing prepaid cutoffs, and queuing sync events for when connectivity returns — required careful thought about eventual consistency. The gateway and cloud can diverge in their view of the world; reconciling them correctly without double-counting or missing events took multiple iterations.

Payment Integration Nuances

Integrating both Stripe and Mollie for wallet top-ups revealed important differences in how European payment processors handle webhooks. Stripe’s webhook delivery is reliable but can retry after delays. Mollie’s webhook timing is less predictable. Building idempotent payment processing — ensuring a payment event processed twice has exactly the same effect as processing it once — was non-negotiable for a billing system.

The Prepaid Model Changes Behavior

What surprised me most was the behavioral effect of switching from post-paid to prepaid billing. In post-paid models, operators chase unpaid invoices. In prepaid models, tenants self-manage their budgets and top up proactively. This shift reduced the operator’s administrative burden dramatically. The low-balance notification system — alerting tenants at 20% and 10% remaining balance — was a small feature with an outsized impact on user satisfaction and fewer support requests.

Regulatory Considerations for Metering

In Germany, electricity metering for billing purposes is subject to Mess- und Eichgesetz (calibration law) requirements. Smart meters used for billing must be certified for accuracy. This is a regulatory consideration that any commercial deployment of Energy Backbone must address — the software is production-ready, but the hardware selection must comply with local metering regulations.