How GridWitness works
From the meter on your wall to a UTC-coherent map of the GB grid.
What kind of node can you be?
Contribute at whatever level your hardware supports. Even a single frequency node is useful; a handful of GPS-anchored PMUs sync the entire fleet.
Frequency node
Any frequency-capable meter (Shelly, Tasmota/ESPHome, some inverters). Gives system frequency at 1–5 s, self-synced against NESO's national trace.
3-phase node
Shelly Pro 3EM, Emporia Vue, CT banks, industrial Modbus meters. Per-phase voltage, current, power and power factor — feeder-located if you data-share.
PMU node
DIY GPS PMU (OpenPMU / Red Pitaya / Teensy+GPS-PPS). Phase angle versus UTC at sub-microsecond timing — the fleet's absolute reference.
Privacy is tiered, and it's yours to set
Consent is per data-type and location is tiered. The default is anonymous, frequency-only.
No address. Only a rough region derived from your connection. Fully useful for frequency.
You pick your GB region from a list. Better regional mapping, still no address.
You enter a postcode so we can place readings on the network. The postcode never leaves the server; only a coarse derived area (a grid supply point or primary substation) is attached to your data.
We're honest about the ceiling: even in data-share mode we pin data to a grid supply point or primary substation — never your individual street cable. Read the full privacy statement →
Made coherent by time
Cheap sensors don't agree on the clock. GridWitness corrects for that in four stages so the whole fleet lines up:
- Stamp early. Prefer device/source timestamps, as close to the sensor as possible.
- Correct transport offset. The protocol carries client-send and server-receive times for an NTP-style offset estimate.
- Self-sync against NESO. Cross-correlate each node's frequency against the national 1 s trace to recover its clock error — no GPS needed.
- GPS anchors. T3 PMU nodes carry UTC-true time and become the fleet's absolute references.
Already running surveys? Contribute those too
Electricians and engineers log power-quality surveys all the time — a week in one building, a few days in another. Upload your analyser exports (CSV or PQDIF, up to 100 files at once) and we keep only the frequency and voltage: current, power and everything else are discarded before anything is stored. Every survey site is a fresh point on the grid, so together they build a real-world voltage map nobody currently has.
It stays your data — withdraw it or download a copy any time, and we never sell it. Contribute a survey →