Smart home · Guide
Home energy monitoring with Home Assistant: a practical setup for Portuguese homes
You can't cut what you can't see. A local Home Assistant energy dashboard shows exactly where your kWh go, how much solar you use yourself, and when to run big loads. Here's a robust setup that suits Portuguese houses.
This guide contains affiliate links. If you buy through them we may earn a small commission, at no extra cost to you. It never changes what we recommend. How we make money.
Key takeaways
- Start with one whole-house meter at the electrical board; add smart plugs only for the loads you want to understand.
- Many Portuguese rural homes have three-phase supply — choose a three-phase meter (e.g. Shelly Pro 3EM) if you do.
- Keep everything local: Home Assistant + local APIs keep working when clouds or internet links don't.
- The money is in automations: water heater, pool pump and charging on solar or off-peak hours.
The architecture in one picture
- Home Assistant on a small, always-on box (Home Assistant Green, a mini-PC or a Raspberry Pi with an SSD).
- A whole-house meter at the quadro elétrico: grid import/export, per phase.
- Solar data from your inverter, ideally through a local integration (Modbus/TCP or a local API) rather than only the vendor cloud.
- Device-level data where useful: smart plugs or relays with metering on the water heater, pool pump, AC, freezer.
- The Energy dashboard in Home Assistant, plus a tariff sensor so costs are calculated correctly.
Step 1 — The whole-house meter
Check your supply first: the contract and the main breaker tell you whether you are single-phase (monofásico) or three-phase (trifásico). Then choose a meter accordingly:
Shelly Pro 3EM
Best for: Three-phase homes, solar export measurement
DIN-rail meter with current clamps on each phase, measuring both import and export. Works locally with Home Assistant. Has to be installed in the electrical board — by an electrician.
- Three phases, bidirectional
- Local API, no cloud needed
- Professional installation
Shelly EM (Gen3)
Best for: Single-phase homes, or one big circuit
A compact meter with two clamp inputs — for example grid plus solar, or grid plus a heat pump.
- Affordable
- Two channels
- Single-phase only
Step 2 — Get your solar data in
Most inverter brands sold in Portugal have a Home Assistant integration, either official or via the community store (HACS). Prefer local polling: rural internet (fibre, 4G or satellite) drops occasionally, and you don't want your automations to depend on it. If your inverter only offers a cloud API, the whole-house meter still lets you calculate self-consumption from the grid side.
Step 3 — Configure the Energy dashboard
- Settings → Dashboards → Energy: add grid consumption and return (export) sensors from your meter.
- Add solar production from the inverter.
- Add individual devices (smart plugs, relays) under “Individual devices”.
- Set the price: a fixed €/kWh for simples, or an entity that switches price for bi-horário — the built-in Tariff option of the Utility Meter helper is the easiest way.
- Give it a week before drawing conclusions; a full year is ideal for sizing solar or a battery.
Step 4 — Automations that pay for the hardware
| Automation | Trigger | Typical effect |
|---|---|---|
| Water heater on solar surplus | Export above ~1.5 kW for 5 minutes | Turns midday surplus (worth €0.05–0.08) into hot water (worth €0.17+) |
| Water heater on off-peak | 22:00 on bi-horário, if not already hot | Moves 20–30% of a typical home's use to the cheap period |
| Pool pump split | Solar hours in summer, off-peak in winter | Large, predictable load moved for free |
| Charging window | Solar surplus or off-peak | Cheapest kWh for an EV or PHEV |
| Standby hunter | Weekly report of night-time base load | Finds old fridges, always-on PCs, faulty heaters |
These automations are what make a bi-horário tariff and self-consumption solar pay off.
Holiday homes and remote access
If the house is empty for weeks, Home Assistant's mobile app gives you alerts (power cut, freezer temperature, water leak) and lets you switch loads remotely. Expose it securely — the official Nabu Casa cloud, or a zero-trust tunnel — and never by opening a port on your router.
Shopping list
- Home Assistant Green or a mini-PC
- Whole-house meter: Shelly Pro 3EM (3-phase) or Shelly EM (1-phase)
- Energy-monitoring smart plugs for appliances
- Optional: a Zigbee coordinator for low-power sensors
Frequently asked questions
Can I read my E-REDES smart meter directly?
Many E-REDES smart meters have a local HAN port and community projects can read it, but it depends on meter model and may need E-REDES to activate it. A clamp meter at your board works regardless.
Do I need three-phase monitoring?
If your supply is three-phase, yes — measuring one phase gives misleading totals and export figures.
Does this work without internet?
Yes, if you choose devices with local integrations. That's the main reason to prefer Shelly-style local devices over cloud-only gadgets.
Sources
- Home Assistant — Energy management documentation — Home Assistant (accessed 29 October 2026)
- Home Assistant — Utility Meter integration (tariffs) — Home Assistant (accessed 29 October 2026)
- Shelly — product documentation — Shelly Group (accessed 29 October 2026)