Solar PV and the customs office: electricity excise duty
Sources checked
For solar generation, the customs office deals with electricity excise duty; that is a separate issue from income tax on surplus sales. The legislation reviewed for the Slovak guide contains a specific regime for renewable sources up to and including 50 kW, but its application also depends on the person and activity.
Read the current provision for your case
The guide discusses Section 15a rather than assuming that an older 10 kW rule covers every installation. A particular exemption does not establish that an owner has no other contractual, reporting or tax obligations.
Confirm the operator, source power, electricity use and any sale or supply arrangement. Do not apply the filing duties of a registered excise taxpayer automatically to every household.
Ask a precise question
Provide the customs office with the installation's rated characteristics, identity of the operator, connection arrangement and description of electricity use. Ask which provision applies and whether registration, notification, records or returns are required for those facts.
Keep that answer separate from an income-tax or social-insurance assessment. A seller's informal assurance about a small installation is not a substitute for identifying the applicable statutory regime.