Terms of service
The terms for using Epilykos, the software and this documentation.
Privacy
What Epilykos does and does not do with your data, including backups to Google Drive.
Development guide
How Epilykos is built, how to run it locally, and where to add cards and data sources.
Last updated: 14 November 2026.
These terms explain what you can expect from Epilykos and what is up to you. They are written in plain language. By installing or using Epilykos, or this documentation, you agree to them. If you do not agree, do not use it.
What Epilykos is
Epilykos is free, open-source software that you install and run yourself, on your own box or server, to watch and control your own solar and energy equipment. The project does not run a service for you: there are no accounts, and your readings never pass through us. See Privacy for what is and is not sent anywhere.
The licence
Epilykos is released under the GNU General Public License, version 3. You may use, study, change and share it under that licence, and the licence is the full statement of those rights. These terms add nothing that restricts them. The licence's own sections on warranty and liability apply to the software, and the points below are a plain-language summary of them.
You run it, and you are responsible for it
You are responsible for the box and network Epilykos runs on, for keeping it up to date, for who can reach it, and for the passwords, tokens and keys you store in it. If you expose Epilykos to the internet, you are responsible for doing that safely: use a strong password and turn on two-step sign-in.
Controlling your equipment
Epilykos can read from and, once you switch it on, change settings on inverters, batteries, switches and other devices. Changing equipment settings can damage it, void its warranty, or create unsafe conditions. Device changes are off until you allow them. Before you change anything, check what the manufacturer says is safe for your equipment. Do not rely on Epilykos for anything where a fault could hurt someone or cause serious damage, and do not use it as your only safety or protection system.
Figures are not guaranteed
Readings, forecasts, the Virtual Battery estimate, the prepaid meter balance, savings and similar figures are calculated from the data your equipment and outside services provide. They can be wrong, late or missing. Do not use them as a meter reading, for billing, or as the basis of a legal or financial decision. Your utility's meter and your equipment's own displays are the source of truth.
Backups
Backups are your responsibility. Epilykos can send encrypted copies to a place you choose, but it cannot promise that a copy exists, is complete, or can be restored. Check your copies from time to time with Check copy. The passphrase that locks a remote backup cannot be recovered by anyone: if you lose it and the box, those copies cannot be opened.
When you use a storage service such as Google Drive, your use of that service is also covered by its own terms. Epilykos asks that service only for access to the files it creates itself.
Other services
Epilykos can connect to services you choose, such as Solcast, Home Assistant, Tuya, Telegram and weather providers. They are not run by the project, and their terms and limits apply to you. API keys and accounts for them are yours.
What you agree not to do
Do not use Epilykos or its documentation to break the law, to interfere with other people's equipment or networks, or to gain access to systems you are not allowed to use.
No warranty
Epilykos and this documentation are provided as they are, without warranty of any kind, to the extent the law allows. That includes any promise that it is correct, reliable, secure, or suitable for your purpose.
Limit of liability
To the extent the law allows, the project and its contributors are not liable for any loss or damage that comes from using, or being unable to use, Epilykos, including loss of data, lost savings, damage to equipment, or loss of power. Some places do not allow these limits, and then they apply only as far as the law lets them.
Support
Help is on a best-effort basis from the community. There is no guaranteed response time. The best way to ask for help or report a problem is an issue on the Epilykos project on GitHub.
Changes and contact
The project may change these terms, and when it does the date at the top changes with them. Using Epilykos after a change means you accept the new terms. Questions about these terms can be raised as an issue on GitHub.
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