# FAQ

> Stub — frequently asked questions.

## Does ETM PowerSync send my data to the cloud?

No. Control runs locally, on the box, and keeps working without internet. The only
component that connects to the internet on its own is the OpenMeteo weather plugin: it
sends only the site's coordinates (rounded to about 1 km), its altitude and the
orientation of the panels. Measurements, consumption and the tariff stay with you.
Remote access is disabled by default; it opens only if you enable it yourself in the
app. That is an architectural decision, not an option.

## Is the project open source?

The foundation (`powersync-core`) and the plugins are under GPL-3.0. So is the optimiser
client built into the energy engine — everything linked against nymea is. The
optimisation **business logic**, however (tariff arbitration, forecasts learned from
your installation), is proprietary: it runs in a separate process, reached through an
open, documented interface. Optimisation runs at your place, on the box or on a machine
in your local network.
That IPC boundary is the heart of the Open Core model — the plugin stays free, the
business logic stays proprietary.

## What is the difference between Community and Pro?

Two editions, not three — the prediction layer has not been sold separately since
2026-10-14; it is part of Pro.

- **Community** — the GPL-3.0 foundation, self-hostable: deterministic rule-based
  control, solar surplus, load shedding, [PV production forecast](fonctionnalites/prevision-pv.md)
  from physical models (beta, displayed, not used to decide), REST/MQTT API. No
  subscription.
- **Pro** — installed by ETM-Schurig: adds tariff arbitration and the prediction layer
  (production and consumption forecasts learned from your installation, heat-pump
  thermal inertia). **No
  subscription either**, and everything stays local.

Tariff arbitration and prediction are on the **roadmap**: the Open Core boundary already
exists, the functions it separates are not all shipped. See
[etm-powersync.fr](https://etm-powersync.fr/en/hems.html).