What to demand
A written guarantee in the contract: the term (usually 1 year), what is covered (connections, panel, testing), response time to claims.
What is NOT covered
Damage from overvoltage in the network, flooding, incorrect operation, changes made by others without the contractor.
How to formalize
The act with the guarantee, the test protocol, photos, the scheme — the document is signed at acceptance.
What if problems appear
The warranty claim is written; the contractor must fix it within the term; if refused — the protocol and the expertise.
Guarantee for the devices
Devices — the manufacturer's guarantee (2-5 years); keep the receipts. The work guarantee and the device guarantee are different things.
Why it matters
Without a guarantee, «it was like this» is possible. The document forces the repair within the term.