We do not sell dreams built on hypothetical savings. We install systems that make your bill predictable — and we give you the figures to check it.
ETM PowerSync came out of what we see in the field. As an electrical contractor in Alsace, we have been installing solar PV, heat pumps and EV chargers for years. And the same problem keeps coming back: capable equipment that does not talk to itself. The solar surplus goes out to the grid while the car charges in the evening at full price. The heat pump runs at the worst possible moment. Each device does its own job in isolation.
1. Evidence before the promise. The energy market overflows with unverifiable savings percentages. We prefer a PV*SOL simulation, a room-by-room heat-loss audit, and assumptions you can challenge. If a figure does not survive an engineer's scrutiny, it has no business on a brochure.
2. Your data stays with you. Optimising an energy installation means knowing your consumption habits. That data is intimate. Our optimisation logic runs locally, on your hardware — not on a remote server. This is not a premium option, it is the default architecture.
3. No proprietary lock-in. ETM PowerSync is built on nymea.io, an open source IoT platform, following an Open Core model. The foundation is free software (GPL3). You are not trapped in a closed ecosystem that can disappear or change its terms overnight.
In France, since 1 June 2026, the buy-back tariff for surplus rooftop solar is set at 1.1 c€/kWh excl. VAT (decree of 1 June 2026, published in the Journal officiel of 4 June 2026). In Germany, the EEG feed-in tariff for new rooftop arrays sits well below the energy price you pay for imported electricity, and keeps degressing. In both markets the conclusion is the same: selling your surplus and buying it back in the evening at full price gives the difference away.
The consequence is direct: every solar kilowatt-hour consumed on site — rather than exported and bought back — is the one with the best financial return. That is precisely what a HEMS does: maximise self-consumption in real time, with no manual intervention. The regulatory framework does not create the case for self-consumption, it simply makes it unavoidable.
Sources: decree of 1 June 2026 setting the purchase conditions for electricity from photovoltaic installations — Journal officiel, 4 June 2026 · legifrance.gouv.fr (France) · bundesnetzagentur.de for the applicable EEG rate (Germany)
Optimisation software is only as good as the installation it drives and the real data available to it. That is our difference from purely software-based products: we size, we fit, we measure. When our prediction layer estimates tomorrow's output, it will build on the actual orientation and capacity of your array — not on a generic model. That is an advantage a community project, however good, cannot offer.
It is also why we stand behind the "powered by nymea.io": we are not reinventing an IoT platform, we build value where it counts — in local optimisation and in the installer's craft.
No. Everything runs locally, on your hardware. No ETM server is required for normal operation: the controller optimises your installation on its own, even offline. ETM-Schurig handles installation, updates and support — but operational independence is the default architecture, not an option.
The nymea.io foundation is licensed under GPL-3.0 and public on GitHub. The optimiser protocol is documented. That means the code and the documentation exist independently of us: another developer or installer can build on them. This is not a promise on our part, it is a legal consequence of the licence.
Updates arrive through the ETM APT repository — like any Debian package. Even with no updates, the system keeps running as it is, locally, indefinitely. We cannot disable your installation remotely: it does not call our servers.
Optimising an energy installation means knowing your consumption habits hour by hour — intimate data. Processing it locally is a decision that this data never leaves your site. It is also a reliability advantage: the system works with no network dependency.
An individual study, with quantified assumptions that hold up. A technical contact answers you.