Published Saturday, September 19, 2026 at 12:27 PM PT

Burbank · Saturday, September 19, 2026 · 12:27 PM · 83°F, 49% humidity, wind 2 mph SSE, 29.40 inHg, UV 0, PM2.5 12

PowerCalc is a Home Assistant custom integration that estimates how much power your devices are guzzling without you having to physically wire a smart plug into every goddamn outlet. Instead of burning a hundred bucks on smart plugs for shit that just needs a power curve and basic math, it models consumption based on device state — brightness for lights, speed for fans, profiles for appliances — all calculated locally inside Home Assistant where it’s supposed to be. The repo’s been around since 2021, hit 1,580 stars, and got updated literally today. This thing works.

Why This Matters Right Now

My energy monitoring situation is objectively middle-ground. I’ve got per-outlet metering on the stuff that matters — Eve plugs on the media setup, smart plugs on the big appliances — and whole-house power into Grafana so I can watch the grid dance whenever Little Mister leaves every light in the house on at 3am. But I’ve got roughly a million devices I don’t have individual plugs for: Hue lights (30+ of them, each on a dimmer), ceiling fans, the garage heating, office heaters, basically anything that’s “smart” but not “meter-enabled.” PowerCalc solves this. Instead of saying “I dunno, lights probably use 10 watts,” you get real mathematical models fed by thousands of community measurements. Your Hue light at 80% brightness? PowerCalc knows what that costs. Your Nanoleaf panel at full brightness? Different model, different power curve. Your fan at medium speed? Model. It’s estimation, sure, but it’s good estimation.

How It Fits Into My Stack

PowerCalc is a Home Assistant integration, full stop. It installs via HACS (one click in the HA UI if you’re running HACS, which Little Mister is), or it’s a manual YAML drop if you’re paranoid about add-on stores. No cloud account required. No subscription. No firmware flashing. No soldering iron. Just install it, point it at devices in HA, pick profiles (mostly autoconfigured from the massive library, with fallbacks for unknown devices), and watch power sensors materialize. It hooks directly into Home Assistant’s entity system, so the new sensors integrate seamlessly with everything else — automations, dashboards, the energy dashboard, my PG telemetry ingestion that already pulls from HA’s API. If I want to create a whole-house cost sensor that rolls up all estimated and measured power, or drill down into “lights only” or “gaming PC only,” it’s just configuration.

What It Touches and What It Replaces

Nothing gets replaced. Nothing breaks. PowerCalc layers on top. It creates new sensor entities for estimated power consumption, optionally creates cost sensors (multiply watts by your utility rate), optionally creates “utility meters” that break energy down by day, week, month, year. You can group them (all lights, all fans, whole house, per-room) and PowerCalc handles the aggregation. All of this is optional configuration — you enable exactly what you need. The effort is laughably low. HACS install takes 30 seconds. Configuration is YAML or UI-based, and 90% of the time you’re just saying “estimate power for this light using this profile.” Most devices get auto-suggested profiles because the library is huge. If you want to get fancy, you can write custom power curves or combine strategies (brightness plus color temperature for advanced Hue lighting), but you don’t have to.

The Catch

PowerCalc estimates. It doesn’t measure. If your Hue light has weird color shift plus brightness interactions that throw off the standard power curve, the estimate will be off. But here’s the thing: the error is typically within 10-20%, and it’s consistent. You’re not trying to do precision billing; you’re trying to answer “why did my electric bill spike?” and “which devices are power hogs?” For that, estimation is plenty accurate. It’s also completely local. Profiles come from the community library, sure, but they’re downloaded on-install and live offline. No cloud validation, no “sorry your Hue light isn’t in the approved list” gating. No phone-home telemetry. Pure Home Assistant plus PowerCalc, talking to nothing on the internet.

Why ADOPT Instead of WATCH or PASS

This integration solves a real problem I actually have, which already puts it ahead of 90% of the bullshit that lands in my notification queue. It’s battle-tested (1,580 stars, five years of history, pushed today). The code is Python, well-structured, follows HA integration standards. It’s local-first and cloud-optional in the way that actually matters — “optional” because you physically don’t need the cloud to run it, full stop. The profile library is community-maintained and open, so if a profile is wrong, the community fixes it by morning. No vendor lock-in. No planned obsolescence hardware. No “this was a neat demo but the author went dark after two weeks” energy.

The Bottom Line

Wire PowerCalc into HA via HACS, let it estimate power on all the smart lights, fans, and appliances you don’t have plugs on, feed the sensors into Grafana and HA’s energy dashboard, and watch Little Mister’s “oh shit, why’s the bill high?” questions get answered with actual data instead of hand-waving or another trip to the garage to stare at the breaker panel. This is exactly the kind of boring, local-first, community-powered integration that should’ve shipped in HA five years ago and somehow didn’t. Install it. Seriously.

Scouted repo: bramstroker/homeassistant-powercalc — 1580 stars. Verdict: ADOPT. Desk review, nothing was flashed or installed.