LoRaWAN Electricity Sub-Metering Systems

What is Electricity Sub-Metering

You have one main meter from the utility. It tells you total building consumption. But which tenant used what? Which EV charging station drew how much power? Is your solar installation actually producing what the salesman promised?

You don't know. That's the problem sub-metering solves.

Sub-meters measure consumption at the unit, circuit, or equipment level. Each apartment gets its own meter. Each EV charger gets tracked individually. Each solar inverter gets monitored separately. Then you know exactly what's happening - who's using what, what's wasting energy, what's underperforming.

Without sub-meters, you split bills equally (unfair to light users) or estimate (causes disputes). With sub-meters, you bill based on actual consumption and find energy waste you didn't know existed.

LoRaWAN Advantages for Electricity Monitoring

No data cables through electrical panels: Traditional sub-metering requires wired connections (RS-485, Ethernet) from meters to collection systems. LoRaWAN operates at 868MHz (EU) or 915MHz (US) - signals penetrate concrete walls and metal enclosures. Install meters anywhere without running data cables.

Power harvesting options: CT clamps can harvest power from measured current - no batteries or external power needed. Devices like the Milesight CT101 use supercapacitors charged from the measured current itself. Other options use replaceable batteries lasting 5-10 years.

Scalability: One LoRaWAN gateway covers entire building complex, solar farm, or RV park. Add meters without network infrastructure changes - just provision new devices and they join the network. Single gateway handles hundreds of meters.

Installation without downtime: CT clamps install without breaking circuits or shutting off power. Licensed electrician clamps around existing conductors in seconds. No service interruption.

Hardware Options

CT Clamp Sensors

Self-powered CT clamps (Milesight CT101 and similar): Current transformers that harvest power from measured current using supercapacitors. Zero maintenance - no batteries to replace ever. Clamp-on installation without circuit interruption.

• Measurement range: 0-100A or 0-300A typical
• Accuracy: ±3% typical for CT clamps, ±1-2% for calibrated models
• Power: Self-harvesting (supercapacitor) or battery-powered
• Installation: Clamp around L1, L2, L3 conductors (no cutting)
• Use case: Retrofit installations, minimal downtime

Battery-powered CT clamps: Alternative to self-powered. Uses replaceable batteries (5-10 year life). Sometimes more accurate than self-powered models. Options: Adeunis ARF8180AA, Elsys EMS.

Three-phase monitoring: Install 3 CT clamps for three-phase systems. Measure each phase individually. Calculate total power, detect phase imbalance, monitor power factor.

DIN Rail Energy Meters

Panel-mounted meters: Install in electrical distribution boards on DIN rails. More accurate than CT clamps (±1% vs ±3%). Require licensed electrician installation - circuits must be de-energized during installation.

• Measurement: Voltage + current = true power (Watts)
• Accuracy: ±1% typical, ±0.5% for revenue-grade
• Features: kWh accumulation, power factor, THD (total harmonic distortion)
• LoRaWAN options: Eastron SDM630-Modbus + LoRaWAN gateway, or integrated models
• Use case: New construction, panel upgrades, high-accuracy requirements

Smart Plugs with LoRaWAN

For individual appliances or temporary monitoring. Plug between outlet and device. Track consumption of specific equipment without panel modifications.

• Range: Up to 16A per plug (3.6kW @ 230V)
• Use case: Individual appliance tracking, temporary monitoring
• Limitation: Not suitable for hardwired equipment or high-power devices

Applications

Solar Production Monitoring

Sub-meter solar inverter output separately from building consumption. Track generation vs consumption patterns in real-time.

What gets measured:

• Solar production (kWh generated)
• Building consumption (kWh used)
• Grid import/export (net metering)
• Self-consumption percentage

Use case: Calculate ROI on solar installation. Optimize consumption to maximize self-consumption during daylight hours. Identify when to charge batteries or delay high-power loads.

EV Charging Stations

Each charging point gets individual sub-meter. Bill users based on actual kWh delivered, not flat rates.

Implementation: CT clamps on each charger circuit. Monitor current draw, calculate energy delivered. Integrate with billing system or RFID card readers.

Load balancing: Monitor total facility power vs available capacity. Throttle chargers dynamically to avoid exceeding grid connection limits. Prioritize charging based on user tier or vehicle SOC.

RV/Camper Electrical Hookups

Campgrounds with electrical hookups meter individual sites. Charge based on usage instead of flat daily rates.

Typical setup: Each site has 15A, 30A, or 50A service. CT clamp on feed to each site pedestal. Dashboard shows current usage, alerts when approaching amperage limit.

Billing: Calculate kWh consumed during stay. Generate invoice at checkout. Detect usage patterns (e.g., running AC all night) that justify dynamic pricing.

Multi-Tenant Buildings

Individual apartments or commercial units get electricity sub-meters. Fair billing based on actual consumption.

Scenarios:

• Buildings with central HVAC but individual unit appliances
• Commercial buildings with mixed tenants (office, retail, restaurant)
• Industrial facilities with multiple tenants sharing building

Implementation: CT clamps on main feed to each unit. DIN rail meters for higher accuracy if panel space available. Automated monthly billing integration.

Industrial Equipment Monitoring

Track consumption per machine, production line, or process.

Applications:

• Preventive maintenance (detect bearing failure via increased current draw)
• Energy efficiency audits (identify inefficient equipment)
• Production cost allocation (attribute energy costs to specific products)
• Load shedding (disable non-critical equipment during demand response events)

Data Pipeline

LoRaWAN gateway → Network Server (ChirpStack, TTN) → InfluxDB → Grafana or custom dashboard.

Data stored:

• Instantaneous power (Watts)
• Cumulative energy (kWh)
• Voltage (V)
• Current (A)
• Power factor (three-phase systems)
• Frequency (Hz)

Visualizations:

• Real-time power consumption graphs
• Daily/weekly/monthly kWh totals
• Cost tracking based on utility rates (with time-of-use pricing)
• Load profile heatmaps
• Comparative analysis (unit A vs unit B)

Alert conditions:

• Usage exceeds contracted capacity (demand limiting)
• Voltage outside 220-240V range (equipment protection)
• Current imbalance >15% on three-phase (wiring issues)
• Power factor <0.9 (inefficiency penalties)
• Equipment offline (zero current when should be running)

System Design Considerations

Gateway placement: Central location with sight lines to electrical panels and meter locations. Electrical rooms often work well - metal enclosures create RF shielding, so test coverage before finalizing placement. For large buildings with multiple floors or metal structures, plan for multiple gateways or external antennas.

CT clamp sizing: Match CT clamp range to expected current. 100A CT on 200A circuit won't work. Undersized CT clamps saturate and give false readings. Oversized CTs sacrifice low-end accuracy. Rule of thumb: size CT for 150% of maximum expected current.

Voltage reference: CT clamps measure current only. To calculate power (Watts = Volts × Amps), you need voltage. Options:

• Assume fixed 230V (3-5% error typical)
• Use voltage reference sensor in panel (more accurate)
• DIN rail meters measure both V and I directly

Transmission frequency: Balance between data freshness and battery life (for battery-powered models):

• Every 10 minutes: Real-time monitoring, 2-3 year battery
• Every 30 minutes: Good compromise, 5-7 year battery
• Every hour: Long battery life, sufficient for billing

Self-powered models (Milesight CT101) transmit based on current flow - no battery considerations.

Network server choice:

• Self-hosted ChirpStack: Full control, no per-device fees, requires sysadmin
• The Things Network: Free, fair use limits, good for small deployments
• Commercial providers: Managed service, SLAs, higher cost

Billing Integration

Manual billing: Export monthly consumption reports as CSV. Import into billing software or create invoices manually. Works for small deployments (<20 units).

Semi-automated: Scheduled report generation (monthly). Staff reviews for anomalies (zero consumption = meter offline, 10x normal = wiring error). Adjust before invoicing.

Fully automated: API integration between metering database and billing system:

• Automatic invoice generation based on rate tables
• Time-of-use pricing (peak/off-peak rates)
• Demand charges (based on peak 15-minute interval)
• Exception handling for unusual patterns
• Integration with property management software

Common Implementation Mistakes

CT clamp orientation: CT clamps have polarity. Installing backwards shows negative power (generation instead of consumption). Mark conductor direction before installation.

Measuring neutral instead of phase: CT must clamp around phase conductor (L1, L2, L3), not neutral (N) or ground (PE). Neutral current only reflects imbalance on three-phase systems.

Metal enclosure shielding: LoRaWAN signals attenuate 20-30 dB passing through metal electrical panel enclosures. Test coverage with panel door closed. May need external antenna or gateway placement near panels.

No calibration verification: CT clamps arrive factory-calibrated but transport damage occurs. Verify accuracy against known load before deployment. ±3% spec can become ±10% if damaged.

Single-phase monitoring of three-phase loads: Measuring one phase of three-phase load gives 1/3 of total (at best). Need CT on each phase. Calculate total power = P1 + P2 + P3.

What I Provide

Services:

• System design: CT sizing, meter placement, panel analysis
• Gateway placement planning and RF coverage modeling
• Hardware specification and sourcing guidance (Milesight, Adeunis, Elsys, etc.)
• Network server setup (ChirpStack recommended for self-hosted)
• Data pipeline implementation (InfluxDB + Grafana or custom dashboard)
• Power calculation algorithms (real power, reactive power, power factor)
• Billing integration design (rate tables, time-of-use, demand charges)
• Alert rule configuration
• Load balancing logic for EV chargers or demand response

You own everything:

• Complete source code for data processing and dashboards
• Self-hosted infrastructure (or cloud if you prefer)
• All configuration documentation
• Device provisioning procedures
• Billing integration code
• No monthly platform fees after implementation

Hardware (you source):

• CT clamp sensors (Milesight CT101, Adeunis ARF8180AA, Elsys EMS)
• DIN rail energy meters (optional, for higher accuracy)
• LoRaWAN gateway(s)
• Server (on-premise or VPS) for network server and database

I don't sell hardware. I specify what you need, help you source it, and build the software that makes it work for your specific application.